CRIMEAN STATE MEDICAL UNIVERSITY
NAMED AFTER S.I.GEORGIEVSKY
Digest on pathomorphology
Assistant of professor
І.В.Задніпряний – д.м.н., професор кафедри анатомии КДМУ ім. С.І.Георгієвского
О.Ю.Шаповалова – д.м.н., профессор, завідувач кафедри гістології КДМУ ім. С.І.
Друкується в авторскій редакції.
«Дайджест з патоморфології». – Сімферополь, 2007.-417с. – Мова англ.
«Дайджест з патоморфології» (друге видання) підготовлений Академіком Міжнародної
Академії Патології, завідувачем кафедри патоморфології Кримського державного медичного
університету Олександром Загорулько і доцентом кафедри Тетяною Філоненко. Книга містить
короткий огляд головних тем з загальної і клінічної патоморфології відповідно до програми,
затвердженої Центральним методичним кабінетом вищої освіти Міністерства охорони здоров’я
України. Книга розрахована на студентів медичних вузів, які навчаються англійською мовою.
«Digest on pathomorphology». – Simferopol, 2007. – 417 p.
“Digest on pathomorphology” (second edition) is prepared by Academician of International
Academy of Pathology, Head of the Department of Pathology of the Ctimean State Medical
University, professor Alexander Zagoroulko, PhD, MD and assistant of professor Tatyana Filonenko,
PhD. The book includes the quick review of the main topics on general and systemic
All rights reserved. This book is protected by copyright. No part of this book may be
reproduced in any form or by any means, including photocopying, or utilized by any information
storage and retrieval system without written permission from the copyright owner.
In the preface to the first edition we stated our motive as follows: “We believe that
communication by verbal and written methods are fundamental basis for study and lerning.
Nevertheless, in the mordern setting where knowledge increases so rapidly and in subject such as
pathology where morphological changes are a major component, we consider that the quick review
has an important facilitating role”.
The first edition of the present book is abridged information about the main topics of the
pathomorphology, which combined the efforts of the scientific achievements of the all
pathomorphologists as in theUkraine and other countries as well.
We have attempted to extract the essential elements from the various pathomorphological
literatures for facilitation of the understanding of pathomorphology. Because pathology is the basis of
our medical practice, or, in the words of Sir William Osler, “As is our pathology, so is our practice.”
This book is expected to fulfil the following goal: as an aid to students to revise the subject
quickly near the examinations in short period of time.
PART I. GENERAL PATHOLOGY
INTRODUCTION ON PATHOLOGY
Pathology is scientific study of structure and function of the body in disease. The discipline of
pathology forms a vital bridge between initial learning phase of preclinical sciences and the final
phase of clinical subjects. PATHOLOGY is the study (logos) of suffering (pathos). It is a discipline
involving both basic science and clinical practice and is devoted to the study of the structural and
functional changes in the cells, tissues, and organs that underlie “diseases”.
Pathology studies (1) cause of the disease (etiology), (2) the mechanisms of its development
(pathogenesis), (3) the structural alterations induced in the cells, organs and tissues of the body
(morphological changes), and (4) the functional consequences of the morphologic changes (clinical
CELLULAR INJURY AND CELLULAR DEATH
Etiology of cellular injury
The causes of cellular injury, reversible or irreversible, may be broadly classified into two large
1. Genetic causes.
2. Acquired causes.
The acquired causes of disease comprise the vast majority of common diseases and can be
further categorised as the follows:
1. Hypoxia and ischemia.
2. Physical agents (mechanical trauma, thermal trauma, ultraviolet and ionizing radiation, rapid
changes in atmospheric pressure).
3. Chemical agents and drugs.
4. Infectious agents.
5. Immunologic agents.
6. Nutritional derangements.
7. Physiologic factors.
Acute Cell Injury
Reversible cellular injury is characterized with the ability of the cell to return to its normal
state after withdrawal of an acute stress.
Reversible injury is manifested with hydropic swelling of the cell (cellular edema), dilation of
endoplasmic reticulum, and detachment of ribosomes from the granular endoplasmic reticulum,
dissociation of polysomes into monosomes, mitochondria swelling and enlargement, blebs of plasma
membrane, nucleolar alterations with disaggregation of granular and fibrilar elements.
Irreversible cellular injury or cellular death is necrosis and apoptosis.
Morphogenetic mechanisms of intra- and extracellular accumulations
Mechanisms of the development of intra- and extracellular (stromal) degenerations
(dystrophies) are the followings:
1. Infiltration – redundant accumulation (deposition) of metabolites into the cells and
2. Decomposition (phanerosis) – disintegration of membranous structures of the cells and
3. Perverted synthesis - synthesis of abnormal substances in the cells and tissues.
4. Transformation – formation of one type of metabolism‟s products from common initial
substances for proteins, fats and carbohydrates.
(PARENCHYMAL DEGENERATIONS OR DYSTROPHIES)
Intracellular accumulations are the accumulation of abnormal amounts of various
substances in the cells. The stockpiled substances fall into three categories:
1. A normal cellular constituent accumulated in excess, such as water, lipid, protein, and
2. An abnormal substance such as mineral, or a product of abnormal metabolism.
3. A pigment or an infectious product.
Parenchymal degenerations occur in functional cells such as: cells of a liver, kidneys, a
myocardium and are characterized by accumulation in their cytoplasm proteins, fats and
carbohydrates. It is accompanied by decrease (reduction) of function of enzymic systems and
occurrence of structural changes in cells. The most often causes of parenchymal dystrophies are
hypoxia, the intoxication, and also enzymopathy - genetically determined diseases at which is
observed an inconsistency of enzymic systems in cells. In result enzymopathy there is an
accumulation in cells of any products of a metabolism. Such diseases are named as storage diseases.
Intracellular proteinous degenerations
There are four kinds of intracellular accumulations of proteins:
1. A granular degeneration (dystrophy). Macroscopical kind of organs at this dystrophy
it is determined as “muddy or dim swelling”. At a section the organs are dim, swollen. Microscopical
descriptions of cells on electronics level: presence of electrondense granules in cytoplasm of the cells.
2. Hyaline-drop degeneration (dystrophy) is characterized by the aggregation of small
proteins granules into cytoplasm of cells. It is not determined macroscopically. This dystrophy occurs
in kidneys, liver and myocardium. The cytoplasm of plasma cells shows pink hyaline inclusions called
Russell's bodies representing synthesised immunoglobulins, the cytoplasm of hepatocytes shows
eosinophilic globular deposits of a mutant protein. Mallory's body or alcoholic hyaline in the
hepatocytes is intracellular accumulation of intermediate filaments of cytokeratin. The outcome is
negative. The focal or total coagulative necrosis develops.
3. Hydropic (cloudy, vacuolar, balloon) degeneration is characterized by
accumulation of water within the cell due to cytoplasmic vacuolation. The common causes include
bacterial toxins, chemicals, poisons, burns, and high fever. The affected organ such as kidney, liver or
heart muscle is enlarged. The cut surface bulges outwards and is slightly opaque. Microscopically: the
cells are swollen and the microvasculature compressed. Small clear vacuoles are seen in the cells.
These vacuoles represent distended cisternas of the endoplasmic reticulum. Ultrastructural changes in
hydropic swelling include the following:
Dilation of endoplasmic reticulum.
Blebs on the plasma membrane.
Loss of fibrillanty of nucleolus.
The outcome is negative, because the focal or total colliquative cellular necrosis develops.
4. Keratoid (horney) degeneration is characterized by increase production of keratin
substance. This process may be local and general. The intracellular keratin may be located in
epidermis of skin, keratinic squamous epithelial cells, cervix, and esophagus. Leucoplakia means
hyperkeratosis in mucosa. Leucoplakia may lead to malignization. For example: Squamous cell
carcinoma with keratinization. The groups of keratinized cells can be found in the center of squamous
cell carcinoma‟s areas. These cell‟s complexes here and there look like rose color homogenous found
forms (“canceromatous perls”).
Intracellular fatty degenerations
Intracellular fatty degenerations are the abnormal accumulations of triglycerides within
parenchymal cells. The heart, liver, kidneys are damaged most frequently.
The main cause of fatty degeneration is hypoxia, which may be due to:
1. Excess alcohol consumption (most commonly).
2. Chronic cardiovascular and chronic pulmonary insufficiency.
3. Cachexia, avitaminosis.
4. Infections (e.g. diphtheria, tuberculosis).
5. Late period of pregnancy.
8. Hepatotoxins (e. g. carbon tetrachloride, chloroform).
9. Certain drugs (e. g. administration of estrogen, steroids, tetracycline).
In the case of cell injury by chronic alcoholism, many factors are implicated with increased
lipolysis, increased free fatty acid synthesis, decreased tryglyceride utilisation, decreased fatty acid
oxidation to ketone bodies, and block in lipoprotein excretion.
An alcoholic who has not developed progressive fibrosis in the form of cirrhosis, the enlarged
fatty liver may return to normal if the person becomes teetotaler.
Morphological features of fatty change:
Fat in the tissue can be demonstrated by frozen section followed by fat stains such as Sudan 3
(red color), oil red O and osmic acid.
1. Fatty degeneration of the liver
Macroscopically the fatty liver is enlarged with rounded margins.
The cut surface bulges slightly and is pale-yellow and is greasy to touch. It is called “goose
Microscopically: there are numerous lipid vacuoles in the cytoplasm of hepatocytes. The
vacuoles are initially small (microvesicular), but with progression of the process, the
vacuoles become larger pushing the nucleus to the periphery of the cells (macrovesicular).
At times, the hepatocytes laden with large lipid vacuoles may rupture and lipid vacuoles
coalesce to form fatty cysts. Infrequently, lipogranulomas may appear.
2. Fatty degeneration of the heart
It is also called “Tiger’s” heart.
Macroscopically the heart is enlarged, the chambers are stretched, flabby.
Microscopically we can see dust-like fatty vacuoles in the cardiomyocytes.
It is observed in the papillary muscles and trabecules of the ventricles in the form of bands
(surrounding the veins).
3. The kidneys look like “large white kidney”. They are enlarged, flabby. The cortical
substance is gray with yellow drops.
Outcomes of fatty degenerations are seldom reversible. Necrosis or sclerosis may develop.
Intracellular carbohydrate degenerations
Carbohydrates are divided into 3 groups:
1. Polysaccharides (glycogen).
3. Glycoproteides (mucin, mucoid).
There are several special reactions for identification of these carbohydrates. Best‟s carmine and
PAS (periodic acid-Schiff) staining may be employed to confirm the presence of glycogen in cells.
Polysaccharides and mucopolysaccarides are stained dark pink or red. Staining according to Haile for identification glycoproteides. Glycoproteides are stained blue.
Accumulations of glycogen
Accumulations of glycogen are excessive intracellular deposits of glycogen usually in
patients with an abnormality of either glucose or glycogen metabolism.
Morphological features – appearance of glycogen masses as clear vacuoles within the
cytoplasm developed with special stain – PAS-reaction.
In diabetes mellitus - the prime example of this disorder – the red color granules of
glycogen can be found with large magnification in the epithelial cells of Henley‟s loops and
in the lumen of kidney‟s canals.
Amount of glycogen in the tissues reduces sharply (e.g. in the liver) which causes its fat
infiltration (fatty liver degeneration).
Mucus secreted by mucous glands is a combination of proteins complexes with
mucopolysaccharides Mucin, a glycoprotein, is its main constituent. Mucin is normally produced by
epithelial cells of mucous membranes and mucous glands, as well as by some connective tissues like in
the umbilical cord. Epithelial mucin is stained positively with periodic acid-Shiff (PAS), while
connective tissue mucin does not but is stained positively with colloidal iron. Both are, however,
stained by alcian blue.
Epithelial mucin is associated with:
Catarrhal inflammation of mucous membrane (e. g. of respiratory tract, alimentary tract,
Obstruction of duct leading to mucocele in the oral cavity, chronic appendicitis and gall
Cystic fibrosis of the pancreas or mucoviscidosis.
Mucin-secreting tumors (e. g. of ovary, stomach, large bowel etc.).
There are a lot of diseases, which are due to hereditary factors and connected with metabolism
disturbance. These diseases are called storage diseases or enzymopathy.
A few general comments can be made about all storage diseases:
All the storage diseases occur as a result of autosomal recessive, or sex-(X-) linked recessive
Most of the storage diseases are lysosomal storage diseases. Out of the glycogen storage
diseases, only type II (Pompe‟s disease) is due to lysosomal enzyme deficiency.
According to the type of metabolism disturbance storage diseases have been classified into:
The type of proteinoses, lipidosis and glycogenoses depends on the defect in the enzyme. The
most frequent lipidosis are Gaucher‟s disease, Niemann-Pick disease.
This is an autosomal recessive disorder in which there is deficiency of lysosomal enzyme,
glucocerebrosidase, which normally cleaves glucose from ceramide. This results in lysosomal
accumulation of glucocerebroside (ceramide-glucose) in phagocytes of the body and sometimes in the
neurons. The main sources of glucocerebroside in phagocytic cells of the body and sometimes in the
neurons are the membrane glycolipids of old leukocytes and erythrocytes, while the deposits in the
neurons consist of gangliosides.
Clinically, there are 3 types of Gaucher’s disease:
1. Type 1 or classic form is the adult form of the disease in which there is storage of glycocerebrosides
in the phagocytes of the body, principally involving the spleen, liver, bone marrow and lymph nodes.
This is the most common type comprising 80% of all cases of Gaucher‟s disease.
2. Type II is the infantile form in which there is progressive involvement of the central nervous
3. Type III is the juvenile form of the disease having features in between type I and type II, i.e. they
have systemic involvement like in type I and progressive involvement of the central nervous system
(CNS) as in type II.
In addition to involvement of different organs and systems (splenomegaly, hepatomegaly,
lymphadenopathy, bone marrow and cerebral involvement), a few other features include
pancytopenia, or thrombocytopenia secondary to hypersplenism, bone pains and pathologic
Microscopically large number of characteristically distended and enlarged macrophages
called Gaucher cells which are found in the spleen, liver, bone marrow and lymph nodes,
and in the case of neuronal involvement, in the Virchow-Robin space. The cytoplasm of
these cells is abundant, granular and fibrillar resembling crumpled tissue paper. They have
mostly a single nucleus but occasionally may have two or three nuclei. These cells often
show erythrophagocytosis and are rich in acid phosphatase.
This is also an autosomal recessive disorder characterized by accumulation of
sphingomyelin and cholesterol.
Majority of the cases (about 80%) have deficiency of sphingomyelinase, which is required
for cleavage of sphingomyelin, while a few cases probably result from deficiency of an
The condition presents in infancy and is characterized by hepatosplenomegaly,
lymphadenopathy and physical and mental underdevelopment.
About a quarter of patients present with familial amaurotic idiocy with characteristic
cherry-red spots in the macula of the retina.
The storage of sphingomyelin and cholesterol occurs within the lysosomes, particularly in
the cells of mononuclear phagocyte system.
The cells of Niemann-Pick disease are somewhat smaller than Gaucher cells and their
cytoplasm is not wrinkled but is instead foamy and vacuolated which stains positively with
These cells are located in the spleen, liver, lymph nodes, bone marrow, lungs, intestine and
The most frequent glycogen storage diseases or glycogenosis are Pompe’s disease, Mc Ardle’s
disease and Gierke disease. There is defective metabolism of glycogen due to genetic disorders.
Pompe’s Disease. This is also an autosomal recessive disorder due to deficiency of a
lysosomal enzyme, acid mahase. Its deficiency results in accumulation of glycogen in many tissues,
most often in the heart and skeletal muscles leading to cardiomegaly and hypotonia.
Mc Ardle’s Disease. The condition occurs due to deficiency of muscle phosphorylase
resulting in accumulation of glycogen in the muscle (deficiency of liver phosphorylase). The disease is
common in 2nd to 4th decades of life and is characterized by painful muscle cramps, especially after
exercise, and detection of myoglobinuria in half the cases.
Gierke Disease. This condition is inherited as an autosomal recessive disorder due to
deficiency of enzyme, glucose-6-phosphatase. In the absence of glucose-6-phosphatase, excess of
normal type of glycogen accumulates in the liver and also results in hypoglycemia due to reduced
formation of free glucose from glycogen. As results, fat is metabolized for energy requirement leading
to hyperlipoproteinemia and ketosis. Other changes due to deranged glucose metabolism are
hyperuricemia. The disease manifests clinically in infancy with failure to thrive and stunted growth.
Most prominent feature is enormous hepatomegaly with intracytoplasmic and intranuclear glycogen.
The kidneys are also enlarged and show intracytoplasmic glycogen in tubular epithelial cells. Other
features include gout, skin xanthomas and bleeding tendencies due to platelet dysfunction.
The outcome of storage diseases is unfavorable because of insufficienty of the respective organ.
Mescnchymal (stromal vascular) degenerations develop in the connective tissue as a result of
metabolic disturbances in it.
Stromal vascular proteinous degenerations
Proteinous mesenchymal degenerations occur as mucoid swelling, fibrinoid changes,
hyalinosis and amyloidosis.
The first three types are the stages of connective tissue disorganization. The causes of mucoid
swelling, fibrinous changes and hyalinosis are the same as they are the stages of one process. They are
immunopathological and autoimmune states, hypoxia, infections. These types of connective tissue
disorganization are frequently observed in hypertension, rheumatism and other diseases of the
connective tissue accompanied by immune disturbances as well as in allergic diseases, diabetes
mellitus, etc. In the majority of cases the arterial walls, heart valves, endocardium, epicardium,
articular connective tissue are involved.
1. Mucoid swelling
Mucoid swelling is superficial reversible disorganization of the connective tissue.
These processes are associated with swelling of collagen fibers, increased vascular
permeability (due to glucosaminoglycans (GAG) action) and plasmorrhagia.
Microscopic examination shows metachromasia. Under normal conditions the main
substance is basophilic. In this case staining with toluidine blue demonstrates reddish
Macroscopic appearance is absent.
The outcome may be reversible. In other cases, the development of fibrinoid swelling is
2. Fibrinoid changes
Fibrinoid swelling is deep irreversible connective tissue disorganization.
Fibrinoid is formed as a result of the main substance destruction and more increase in
The appearance of the organs is changed a little.
The main signs are revealed microscopically: the bands of collagen fibers are homogenous,
impregnated with plasma proteins.
Metachromasia is not marked due to GAG depolymerization of the main substance.
Fibrinoid swelling may be generalized (in systemic diseases of the connective tissue) and
localized (in chronic inflammations).
The outcomes are fibrinoid necrosis, sclerosis or hyalinosis.
3. Hyaline changes (hyalinosis)
Hyaline changes (hyalinosis) - (greek “hyalos” - transparent, glass-like) usually refers to an
alteration within cells or in the extracellular matrix, which gives a homogenous, glassy, pink
appearance in routine histologic sections stained with hematoxilin and eosin.
Hyalinosis develops as a result of plasma infiltration, fibrinoid swelling, inflammation,
necrosis, and sclerosis.
Hyalinosis is classified according to its localization (vascular hyalinosis and connective
tissue hyalinosis) and propagation (generalized and localized).
Vascular hyalinosis involves the arterioles and small arteries. In their walls, the
endothelium, basement membranes, and smooth muscle cells are damaged.
Three types of vascular hyaline are distinguished depending on the pathogenetie character
of its formation: 1) simple, 2) lipohyaline, 3) compound hyaline.
Microscopic study of the arteries demonstrates thickened walls with sharply narrowed or
obliterated lumen. At first, hyaline is accumulated in subendothelial areas of the vascular
wall, and then it destroys elastic and middle membranes.
In long-standing hypertension and diabetes mellitus, the walls of arterioles, especially in
the kidney, become hyalinized, owing to extravasated plasma‟s protein and deposition of
basement membrane material.
Hyalinosis of connective tissue is usually localized; it develops in scars, adhesions, in the
areas of chronic inflammation (e.g. “glazed spleen”).
The outcome of hyalinosis is irreversible.
Functional significance of hyalin is different. Thus, vascular hyalinosis may lead to atrophy
or sclerosis, infarction of organs. Local hyalinosis in the cardiac valves results in heart
Amyloidosis is the term used for a group of diseases characterised by extracellular deposition
of fibrillar proteinaceous substance called amyloid.
Nature and etiology
Amyloid is composed of 2 main types of complex proteins:
1. Fibril proteins comprising about 90% of amyloid.
2. P-component constituting the remaining 10% of amyloid.
By electron microscopy the major component of amyloid material (about 90%) consists of
meshwork of fibril proteins. Chemically 2 major forms of amyloid fibril proteins are identified which
have different origins and are seen in distinct clinicopathologic conditions:
AL (amyloid light chain) protein. AL protein of fibrils consists of polypeptides, which may
be made up of whole immunoglobulm light chains or fragment of light chains. AL type of
fibril protein is produced by immunoglobulin-secreting cells and is, therefore, seen in
association with plasma cell dyscrasias. The stimulus for production of AL-amyloid is some
disorder of immunoglobulin synthesis (multiple myeloma). B-cell lymphoma, other plasma
AA (amyloid associated) protein. AA protein consists of polypeptides having 76 amino acids
and is derived from larger precursor protein in the serum called SAA (serum amyloidassociated protein). In the plasma SAA circulates in association with HDL3 (high-density
lipoprotein). SAA is an acute phase reactant protein synthesised in the liver, its level being
high in chronic inflammatory and traumatic conditions. It may be in chronic mflammation
and cancer, familial Mediterranean fever.
Other proteins. In addition a few other forms of proteins are also found in some types of
Transthyretin (ATTR) is a serum protein that transports thyroxine and retinol normally
while a variant of transthyretin is deposited in familial amyloid polyneuropathies and in
A2-microglobulm (A2m) is amyloid seen in cases on long-term hemodialysis (8-10 years).
-amyloid protein (A) is distinctive from A2m and is seen in cerebral plaques as well as
cerebral blood vessels in Alzheimer‟s disease.
Hormone precursor such as procalcitonin and pro-insulin (amyloid endocrine) and keratin
has also been reported in amyloid.
The second component of amyloid is non-fibnllar P-component that constitutes about 10% of
amyloid material. It is synthesised in the liver and is present in all types of amyloid. It is a
glycoprotein resembling the normal serum ar glycoprotein and is PAS-positive
Classification of amyloidosis
A clinical-pathologic classification is widely used currently. According to this classification,
amyloidosis can be divided into 2 major categories each found in distinct clinical settings.
A. Systemic Amyloidosis
1. Primary amyloidosis.
This is one of the two types of systemic or generalised amyloidosis.
Primary amyloidosis associates with plasma cell dyscrasias and conteins AL-protein.
In the 25% to 40% of these cases, primary amyloidosis is the high binger of frank plasma
cell neoplasia, such as multiple myeloma or other B-cell lymphomas.
Primary amyloidosis is often severe in the heart, bowel, skin, skeletal muscle, and less often
in the solid abdominal viscera.
This type of amyloidosis is most common form in the world.
2. Secondary (reactive) amyloidosis.
The second form of systemic or generalised amyloidosis is reactive or secondary in which
the fibril proteins contain AA amyloid.
Secondary or reactive amyloidosis occurs as a complication of chronic infectious or
noninfectious inflammatory conditions associated with tissues destruction such as
tuberculosis, bronchiectasis, chronic osteomyelitis, chronic pyelonephritis, leprosy,
autoimmune disorders (rheumatoid arthritis, dermatomyositis and scleroderma),
inflammatory bowel disease (ulcerative colitis and Crohn‟s disease) and some tumors (renal
cell carcinoma and Hodgkin‟s disease).
Secondary amyloidosis is typically distributed in solid abdominal viscera like the liver,
spleen, kidneys and adrenals Secondary reactive amyloidosis is seen less frequently in
developed countries due to containment of infections before they become chronic, but this
is the most common type of amyloidosis in underdeveloped and developing countries of the
3. Familial amyloidosis.
Familial amyloidosis is seen in patients with familial Mediterranean fever and familial
Familial Mediterranean fever is an autosomal recessive disease. The condition is
characterised by periodic attacks of fever and polyserositis.
Amyloidosis occurring in these cases is AA type.
Hereditary polyneuropathic amyloidosis is an autosomal dominant disorder in which
amyloid is deposited in the peripheral and autonomic nerves.
B. Localized Amyloidosis
Senile cardiac amyloidosis is seen in 50% of people above the age of 70 years. The deposits
are seen in the heart and aorta.
Senile cerebral amyloidosis is deposition of amyloid material in the walls of cerebral blood
vessels in 60% of people above the age of 70 years. Patients of Alzheimer‟s disease also
develop amyloid in the senile plaques.
Endocrine amyloidosis. Some endocrine tumors are associated with microscopic deposits of
amyloid in medullary carcinoma of the thyroid, and islet cell tumor of the pancreas.
Macroscopically, the affected organs are often enlarged and firm and have a waxy appearance.
If the deposits are sufficiently large, painting the cut surface with iodine imparts a yellow color that is
transformed to blue violet after application of sulfuric acid.
The histologic diagnosis of amyloid is based almost entirely on its staining characteristics:
H & E. Amyloid by light microscopy with haematoxylin and eosin staining appears as
extracellular, homogeneous, structureless and eosinophilic hyaline material
Metachromatic stains (Rosaniline Dyes). Amyloid has the property of metachromasia, i.
e. the dye reacts with amyloid and undergoes a color change. Metachromatic stains
employed are rosaniline dyes such as methyl-violet and crystal-violet, which impart rosepink coloration to amyloid deposits.
Congo red. All types of amyloid have affinity for Congo red stain. The stain may be used on
both gross specimens and microscopic sections amyloid stains an orange color. The stain
can also be used to distinguish between AL and AA amyloid (primary and secondary
amyloid respectively). After prior treatment with permangnate on the section, Congo red
stain is repeated: in the case of primary amyloid (AL amyloid), the Congo red positivity
(congophilia) persists while it turns negative for Congo red in secondary amyloid (AA
Sulfated alcian blue. This is a nonspecitic screening test and imparts blue-green color to
amyloid positive areas.
lmmunohistochemistry. More recently, immunohistochemical stains can classify type of
amyloid. Antibody specific for fibril protein gives positive immunoreactivity.
Diagnosis of amyloidosis
Histologic examination of biopsy material is the commonest and confirmatory method for
diagnosis in a suspected case of amyloidosis. If renal manifestations are present, kidney is the
preferred site for biopsy. Otherwise the commonly accessible sites such as rectum, gingiva, and more
recently abdominal fat, are biopsied and are followed by Congo red staining for confirmation.
Pathologic changes in organs
Amyloidosis of Kidneys
Amyloidosis of the kidneys is most common and most serious because of ill-effects on renal
The deposits in the kidneys are found in most cases of secondary amyloidosis and in about
one third cases of primary amyloidosis.
The kidneys may be normal-sized, enlarged or terminally contracted due to ischemic effect
of narrowing of vascular lumina. Cut surface is pale waxy and translucent.
Amyloid deposition occurs primarily in the glomeruli though it may involve peritubular
interstitial tissue and the walls of arterioles as well:
a) In the glomeruli, the deposits initially appear on the basement membrane of the
glomerular capillaries, but later extend to produce luminal narrowing and distortion of
the glomerular capillary tuft.
b) In the tubules, the amyloid deposits likewise begin close to the tubular epithelial
c) The vascular involvement affects chiefly the walls of small arterioles and venules,
producing narrowing of their lumina and consequent ischemic effects.
Amyloidosis of Spleen
Two patterns are observed:
“Sago spleen”. The splenomegaly is not marked and cut surface shows characteristic
translucent pale and waxy nodules resembling sago grains and hence the name.
Microscopically, the amyloid deposits begin in the walls of the arterioles of the white pulp
and may subsequently replace the follicles.
“Lardaceous spleen”. There is generally moderate to marked splenomegaly (weight up
to 1 kg). Cut surface of the spleen shows map-like areas of amyloid. Microscopically, the
deposits involve the walls of splenic sinuses and the small arteries and in the connective
tissue of the red pulp.
Amyloidosis of Liver. The liver is often enlarged pale, waxy and firm. The amyloid initially
appears in the space of Disse, but later as it increases; it compresses the cords of hepatocytes.
Amyloidosis of Heart.
Heart is involved in systemic amyloidosis quite commonly more so in the primary than in
secondary systemic amyloidosis. It may also be involved in localised form of amyloidosis in
very old patients.
Amyloidosis of the heart may produce arrhythmias due to deposition in the conduction‟s
system. The heart shows tiny nodular deposits of amyioid underneath the endocardium.
Later, there may be a pressure atrophy and impaired ventricular function, which may
produce restrictive cardiomyopathy.
Amyloidosis of Alimentary tract. Involvement of the gastrointestinal tract by amyloidosis
may occur at any level from the oral cavity to the anus. Rectal and gingival biopsies are the common
sites for diagnosis of systemic amyloidosis.
The prognosis for patients with generalized amyloidosis is poor. Those with immunocytederived amyloidosis have a median survival of 2 years after diagnosis.
Stromal vascular fatty degenerations
Stromal fatty infiltration is the deposition of mature adipose cells in the stromal connective
tissue. The condition occurs most often in patients with obesity.
As a rule it is a generalized process when the amount of fat in the depots increases.
Depending on the excess of the patient mass compared to the norm, 4 degrees of
obesity are defined:
1. If the patient‟s mass increases by 20 -29% we distinguish 1st degree of obesity;
2. If the patient's mass increases by 30 -49% - 2nd degree;
3. If the patient's mass increases by 50 - 99% - 3rd degree;
4. If the patient's mass increases by 100% and more 4th degree of obesity.
The two commonly affected organs are the heart and the pancreas.
The damage to these organs is most serious.
Subepicardial fat covers the heart as a case, invades the myocardial stroma causing atrophy
If the connective tissue does not grow, heart rupture in the area of fat growth may occur.
In pancreatic lipomatosis beta-cell atrophy and diabetes mellitus are possible.
According to the etiology the following types of obesity are defined:
1. Primary (idiopathic);
There are several types of secondary obesity:
4. Hereditary in Gierke‟s disease.
According to the patient's appearance, obesity may be
According to morphological peculiarities of adipose tissue, it may be:
In hypertrophic type adipose tissue enlarges due to increased volume of fatty cells, in
hyperplastic due to increase in their number. Obesity is a severe complication of mainly endocrine and
nervous diseases. Alimentary obesity is also unfavorable for the organism. As a rule such patients
develop ischemic heart disease.
Local enlargement of adipose tissue (lipomatosis) occurs in Dercum's disease when painful fat
nodes appear in the subcutaneous fat of the lower and upper extremities and trunk.
Sharp reduction in the amount of neutral fat in the whole organism is called cachexia.
Disturbance in cholesterol and its esters metabolism causes atherosclerosis. The wall
of the vessel is thicken everywhere, but much more it is thicken because of the formation of the
atherosclerotic plaque, which are composed with lipids and fibrotic tissue.
Stromal vascular carbohydrate degenerations
Stromal vascular carbohydrate degenerations develop due to disturbance of
glycosaminoglycans and glycoproteids metabolism. When glycoproteid metabolism is disturbed,
chromotropic substances are released from the protein bonds. They accumulate in the main substance
of the connective tissue. Collagen fibers change into mucus-like mass.
Connective tissue mucin is associated with:
Mucoid or myxoid degeneration in some tumors (myxomas).
Neurofibromas, soft tissue sarcomas etc.
Myxomatous change in the dermis in myxedema.
Myxoid change in the synovium in ganglion on the wrist.
The condition results in colliquative necrosis with formation of cavities filled with mucus.
Disturbance of glycosaminoglycans (GAG) is due to hereditary factors as in a storage
It is characterized by deficiency of specific lysosomal enzyme involved in the degradation of
mucopolysaccharides or glycosaminoglycans.
Syndrome of MPS manifests in infancy or early childhood and involves multiple organs and
tissues, chiefly connective tissues, liver, spleen, bone marrow, lymph nodes, kidneys, heart
The mucopolysaccarides accumulate in mononuclear phagocytic cells, endothelial cells,
smooth muscle cells and fibroblasts.
The material is finely granular and PAS-positive by light microscopy.
By electron microscopy, it appears in the swollen lysosomes and can be identified
biochemically as mucopolysaccharide.
The most frequent of them are Pfaundler-Hurler disease, or gargoilism. Its cause is
congenital defect of the enzyme determining GAG metabolism. This disease is characterized
by irregular skeleton growth, “massive” skull, heart defects, inguinal and umbilical hernias,
hepato- and splenomegaly, keratoleukoma (retina opacity).
PATHOLOGY OF PIGMENTS
Pigments are colored substances, some of which are normal constituents of cells where as
others are abnormal and collect in cells only under special circumstances.
Pigments are generally classified into two broad categories:
Endogenous pigments, which are normal constituents of cells and tissues;
Exogenous pigments introduced into the body from environment.
Classification of endogenous pigments
1. Hemoglobinogenic pigments.
Pigments derived from hemoproteins appear as a result of physiologic destruction of
1. Ferritin is a ferroproteide. It is located in liver, spleen, bone marrow and lymphatic nodes.
2. Hemosiderin is iron-containing pigment. Hemosiderin, which is formed by aggregates of ferritin
and is identifiable by light microscopy as golden-yellow to brown, granular pigment, in the
mononuclear phagocytes of the bone marrow, spleen and liver. Hemosiderin is ferric iron that can be
demonstrated by Prussian blue reaction
3. Bilirubin is iron-free pigment.
1. Hematoidin is iron-free, orange-brown crystal pigment. It‟s formed extravascularly in the center of
hemorrhages or foci of necrosis at anaerobic conditions.
2. Hematin is a brown-black pigment derived from hemoglobin and has 2 types:
Chloric hematin is formed in gastric erosions and ulcers as a result of interaction between
hemoglobin and gastric excretion (muriate acid).
Hemomelanin is a brown pigment produced by malarial parasites from hemoglobin; it‟s
taken up by monocytes in the blood and subsequently deposited in the liver and spleen.
3. Porfirin is precursor of hem. It deposits in blood and urine. Clinical symptoms are photophobia,
erythema, and dermatitis. Spleen, bones, teeth, urine becomes of dark red. Porphyria develops when
porphyrin metabolism is disturbed. It may be congenital and acquired. Acquired porphyria is
observed in intoxications, avitaminosis (pellagra), pernicious anemia, and diseases of the liver.
Pathology of hemosiderin’s metabolism
Hemosiderosis occurs in two situations:
It is characterized by local breakdown of red cells in tissues, e.g. in internal hemorrhage.
Mechanism of local hemosiderosis is extravascular hemolysis.
It occurs regularly around areas of bruising and hemorrhage.
In each instance the pigment is localized in cells of the reticuloendothelial system.
In the lungs hemosiderin-laden macrophages (siderofages) are appropriately referred to as
“heart failure cells”.
Visceral siderosis (systemic hemosiderosis).
Mechanism of systemic hemosiderosis is intravascular hemolysis.
It is seen in the liver, spleen and sometimes in kidneys in cases of hemolytic anemia, and in
patients requiring repeated blood transfusion. The generalized form of this condition also
referred to as secondary hemochromatosis.
The pigment imparts a deep brown color to tissues and organs when it is present in high
It can also occur in patients with chronic ineffective erythropoiesis (such as thalassemia
Alcohol ingestion when carried to extremes can lead to hemosiderosis because of the
augmentation of iron uptake by alcohol.
In hemochromatosis, a genetic disorder, the absorbtion of iron is virtually uncontrolled.
The system becomes overload and iron is deposited as hemosiderin in many sites, the main
- Pancreas – associated with fibrosis, which may destroy islet tissue (diabetes mellitus).
- Liver – usually associated with fibrosis (cirrhosis).
- Skin – mainly around swet glands. Excessive melanin is also deposited; hence this
condition is sometimes termed “bronzed diabetes”.
- Heart musle.
- Mesenteric lymph nodes.
Pathology of bilirubin’s metabolism
When the bilirubin content of the serum rises above 34 mmol/l, jaundice appears.
Types of jaundice
1. Prehepatic jaundice (Hemolytic jaundice) - results from an excessive breakdown of the red blood
cell membrane in a variety of conditions, which include:
A genetic membrane defect.
An immune reaction.
Circulating of intravascular toxic substances causing red cell destruction (snake poison).
Hemolytic (familial) jaundice in spherocytosis.
Sickle cell anemia.
Hemolytic disease of the newborn, Rh incompatibility.
Incompatible blood transfusion.
Infections (malaria, clostridial infection, mycoplasma pneumonia, sepsis).
In these conditions the excessive amount of pigment has not pass through the liver for
conjugation. The liver‟s capacity to conjugate it is exceeded, and the level of unconjugated bilirubin
rises in the plasma. It can crystallize out in the tissues, in the brain, may cause necrosis. Injury of
brain may lead to bilirubin encephalopathy (kernicterus).
2. Intrahepatic jaundice (Hepatocellular jaundice) - results from failure both of hepatocytes to
conjugate bilirubin and of bilirubin to pass through the liver into the intestine. Both of conjugated
bilirubin and unconjugated bilirubin increase its amount in blood. The liver is light yellowish-green
color of saffron (“saffron liver”).
Failure of conjugation may involve:
Hepatocellular jaundice, e.g., viral hepatitis and hypoxic necrosis.
Drug-induced jaundice, e.g., disturbance of glucoronide conjugation.
Intrahepatic cholestasis, e.g., congenital intrahepatic occlusion, tumors, inflammations,
Mushroom, arsenic, phosphorous poisoning.
3. Posthepatic jaundice (Obstructive jaundice) - results from an obstruction of the passage of
conjugated bilirubin from hepatocytes to the intestine. Conjugated bilirubin is water-soluble and is
excreted in the urine. The liver is dark green.
Obstructive jaundice may appear in the following causes:
Stenosis of extrahepatic bile ducts.
Gall stones in the major ducts.
Pancreatic tumor compression.
Fibrosis involving the small intrahepatic ducts; the bile ducts became distended with
conjugated bilirubin, which is reabsorbed.
In the liver, bile pigments may appear:
a) As bile pigment droplets in the hepatocytes.
b) As bile impregnations in necrotic areas.
c) As bile casts (bile capillaries, cholangioles, or bile canaliculi).
d) In Kupffer‟s cells.
Pathology of the metabolism of proteinogenic pigments
Melanin is a normal pigment found in the form of fine brown granules in the skin, choroids
of the eye, adrenal medulla, and hair and sometimes in the meninges and intestine.
Melanin is a brown-black pigment synthesized by melanocytes from tyrosine by its
After secretion of the pigment, it‟s taken up by adjacent epidermal cells and phagocytic
melanophores in the underlying dermis
Ultraviolet radiation stimulates the synthesis of melanin.
Various disorders of melanin pigmentation cause generalized and localized
hyperpigmentation and hypopigmentation.
Focal hyperpigmentation: malignant melanoma, nevus, melanosis coli, lentigo.
Nevus is a benign tumor.
Malignant melanoma is a highly malignant neoplasm that invades normal tissues early and
widely and that almost invariably terminates in death.
A dysontogenetic malformation (hamartoma) consisting of nevus cells. It‟s frequently
presented at birth and grows slowly during puberty.
May be generalized melanin pigmentations: a) Addison‟s disease, b) an adrenocortical
insufficiency resulting from destruction of the adrenal cortex, c) chloasma observed during
pregnancy, d) chronic arsenical poisoning.
Localised hypopigmentation: a) leucoderma is a partial albinism and is an inherited
disorder; b) vitiligo is hereditary local hypopigmentation of the skin, c) acquired focal
hypopigmentation from various causes such as leprosy, healing of wounds, syphilis,
radiation dermatitis, etc.
Albinism is an inherited generalized disorder of melanin metabolism in which there is a
decrease or absence of the pigment in the skin and choroid of the eye. Albinos have blond
hair, poor vision and severe photophobia. They are highly sensitive to sunlight.
Pathology of the metabolism of lipidogenic pigments
Lipopigments usually include lipofuscin and lipochrom. Lipofuscin is an insoluble lipid
pigment presented in cells of elderly persons and those with mulnutrition or a chronic
It is a brown intracellular pigment found in hepatocytes, cardiocytes, and neurons.
Organs containing large amounts of lipofuscin are deep brown; in the heart, this is referred
as brown atrophy.
Inhaled pigments. The most commonly inhaled substances are carbon or coal dust; others
are silica or stone dust, iron or iron oxide, asbestos and various other organic substances. Anthracosis
(i. e. deposition of carbon particles) is seen in almost every adult lung and generally provokes no
reaction of tissue injury.
Ingested pigments. Chronic ingestion of certain metals may produce pigmentation. Argyna
is chronic ingestion of silver compounds. Chronic lead poisoning may produce the characteristic blue
lines on teeth. Carotenemia is yellowish-red coloration of the skin caused by excessive ingestion of
Ingested pigments (tattooing). Pigments like India ink, cinnabar and carbon are
introduced into the dermis in the process of tattooing where the pigment is taken up by macrophages
and lies permanently in the connective tissue.
Mineral metabolism disturbance
Minerals play an active role in metabolic processes of the human organism. They are
components of structural elements of cells, enzymes, hormones, vitamins, and pigments.
The most frequent disturbances in medical practice are in the metabolism of calcium, copper,
potassium, and iron.
Calcium metabolism disturbances
I. Dystrophic calcification. Dystrophic calcification refers to the macroscopic deposition of
calcium salts in injuried tissues and does not simply reflect an accumulation of calcium derived from
the bodies of dead cells. It is often visible to the naked eye, and ranges from gritty, sandlike grains to
firm, rock-hard material. Staining with H&E demonstrates calcium salts as deeply basophilic,
irregular and granular clumps. For identification of calcium salts we usually use special reaction called
silver impregnation method or Kossa‟s method. Calcium deposits are stained black.
It may occur in crucial locations, such as:
1. Necrotic tissue, which is not absorbed:
Old caseous lesions of tuberculosis.
Old collections of pus.
Dead parasites (echinococci).
Dead fetus (lythopedion).
2. Tissues undergoing slow degeneration:
Hyaline areas in simple tumors.
Tissues in old age, especially fibrous tissue, cartilage, in the mitral or aortic valves after
rheumatic fever with formation of mitral or aortic stenosis or as in atherosclerotic
coronary arteries with narrowing of those vessels.
II. Metastatic calcinosis (calcium metastases) reflects deranged calcium metabolism
associated with increased serum calcium concentration (hypercalcemia). It has systemic character; its
main cause is hypercalcemia, which may be of endocrine origin in hyperproduction of Parathormone
or hypoproduction of Calcitonine. Calcium salts precipitate in different organs, more frequently in the
lungs, gastric mucosa, kidneys, myocardium, arterial walls. It may be associated with:
Reduction of calcium excretion from the organism.
Multiple fractures of the bones.
Chronic renal failure.
Osteomalacia (when the bone becomes soft).
Lesions of the large intestine (the place of Ca excretion).
Vitamin D intoxication.
The outcome is unfavorable, calcium does not resolve.
Copper metabolism disturbance
This appears in Wilson-Konovalov disease (hepatocerebral degeneration, hepatolenticular
It is a hereditary disease in which liver ceruloplasmin production decreases. Ceruloplasmin
is alpha2-globulin and can bind copper in the blood. As a result, copper becomes free from
unstable bonds with plasma proteins and sediments in the tissue.
Copper accumulates in the liver, brain, kidneys, cornea (in the cornea it looks like greenbrown ring on its margin of the cornea), in the pancreas, testes, etc.
The state is characterized by development of liver cirrhosis, degenerative symmetrical
changes in the brain in the area of lens nuclei, caudal body, pale globe, and cortex.
Copper blood plasma amount is decreased but is increased in the urine.
There are 3 forms of the disease: hepatic, lenticular, hepatolenticular.
The outcome is unfavorable.
Potassium metabolism disturbances
Increased blood (hyperpotassemia) and tissue potassium amount is observed in Addison’s
disease and is associated with the lesion of the adrenal cortex, the hormones of which regulate
Potassium deficiency characterizes periodic paralysis; hereditary disease for which attack of
weakness and motor paralysis are typical.
Formation of Stones
Stones or calculi are dense formations freely lying in the cavities of the organs or in the
Their shape depends on the organs in which they are formed: round in the urinary bladder,
facet in the gallbladder (their faces are lapped to each other), branching in the kidneys.
Their surface may be either smooth or rough.
The color depends on their chemical composition: white (phosphates), yellow (urates), dark
brown or green (pigment).
On cut they may be crystalloid (radial structure), colloid (stratified structure) and colloidcrystalloid (radial-stratified).
Their chemical composition is different, i.e. biliary stones may be cholesterol, pigment,
calcium and combined, urinary - urates, phosphates, oxalates (calcium oxalate), cystin,
Bronchial calculi consist of mucus inlayed with calcium.
Stones are most frequently formed in the bile ducts and urinary tract in cholelithiasis,
urolithiasis, in the excretory ducts of the pancreas, salivary glands, bronchi, crypts of the
tonsils, veins (phlebolith), intestine (coprolyth).
Both general and local factors are important for pathogenesis of calculus formation. General
factors are the main ones; they are acquired or hereditary disturbances of metabolism. Local factors
are congestion, inflammation. The immediate mechanism of calculus formation consists of two
processes: formation of organic matrix and salt crystallization. Each of these may be primary.
Compression with a stone may result in necroses in renal pelvis, gallbladder, bedsores,
perforations, inflammation (pyelocystitis, cholecystitis, cholangitis, etc.).
IRREVERSIBLE CELLULAR INJURY:
Cell death is a state of irreversible injury. It may occur in the living body as a local change (i.
e. autolysis, necrosis and apoptosis), or result in end of the life (somatic death).
Autolysis (“self-digestion”) is disintegration of the cell by its own hydrolytic enzymes
liberated from lysosomes. Autolysis can occur in the living body when it is surrounded by
inflammatory reaction (vital reaction), or may occur as postmortem change in which there is complete
absence of surrounding inflammatory response. Autolysis is rapid in some tissues rich in hydrolytic
enzymes such as in the pancreas, and gastric mucosa, intermediate in tissues like the heart, liver and
kidney, and slow in fibrous tissue.
Necrosis is celullar death in the living body in the disease. Necrosis is defined as focal death
along with degradation of tissue by hydrolytic enzymes liberated by cells. It is invariably accompanied
by inflammatory reaction.
Two essential changes bring about irreversible cell injury in necrosis - cell digestion by lytic
enzymes and denaturation of proteins.
Nuclear changes. The irreversibly damaged nuclei are characterized by one of the following
1. At first nucleus shrinks and becomes dense. This process is called karyopicnosis.
2. After that karyorrhexis develops. This process is characterised by rupture of nuclear membrane
and fragmentation of the nucleus. Nucleus is decomposed into small granules.
3. Also karyolysis may be developed, when the nucleus dissolves.
At electron microscopic level, in addition to the above nuclear changes, disorganization and
disintegration of the cytoplasmic organelles and severe damage of the plasma membrane are seen.
In the cytoplasm, protein denaturation and coagulation or hydration and colliquation take
place. Plasmorrhexis is characterized by decomposition of cytoplasm into clumps due to
coagulation. Then plasmolysis takes place. Plasmolysis is hydrolytic fusion of cytoplasm. Sometimes
we can observe vacuolization and calcification in the cytoplasm.
Stages of necrosis (or morphogenesis):
1. Paranecrosis - reversible changes; as a rule, reversible degeneration.
2. Necrobiosis - irreversible degenerative changes.
3. Death of cells.
4. Autolysis is the enzymic digestion of the dead cell due to effect of catalytic enzymes
derived from lysosomes.
Types of necrosis
According to the mechanisms of development:
1. Direct (from influence of mechanical, physical, chemical, and toxic factors).
2. Indirect (vascular and neurogenous).
According to the cause:
5. Vascular or ischemic.
According to the morphological features:
1. Coagulative necrosis is associated with inhibition of lytic enzymes. Foci of
coagulative necrosis in the early stage are pale, firm, and slightly swollen. With
progression they become more yellowish, softer, and shrunken. The cells do not lyse;
thus, their outlines are relatively preserved. Nuclei disappear and the acidified
cytoplasm becomes eosiniphilic. Waxy (Zenker‟s) necrosis of muscle may occur at
2. Liquefactive (colliquative) necrosis is marked by dissolution of tissue due to
enzymatic lysis of dead cells. Typically, it takes place in the brain when autocatalytic
enzymes are released from dead cells. Liquefactive necrosis occurs also in purulent
inflammation due to the heterolytic action of polymorphonuclear leucocytes in pus.
Liquefied tissue is soft, diffluent and composed of disintegrated cells and fluid.
3. Gangrene – develops in organs and tissues having contact with environment. The
most often examples of gangrene are gangrene of low extremities, uterus, lungs etc.
There are 3 main forms of gangrene - dry, wet and gas gangrene. Contrasting features
of two main forms of gangrene are summarised in Table 1.
Sequester – fragment of dead tissue, which can‟t be autolized, replaced by connective
tissue and which is localized among alive tissue.
4. Infarction – vascular or ischemic necrosis.
5. Fat necrosis is encountered in adipose tissue contiguous to the pancreas and more
rarely at distant sites, as a result of leakage of lipase after acute injury to pancreatic
acinar tissue, most commonly from obstruction of pancreatic ducts. Grossly, fat
necrosis appears as firm, yellow-white deposits in peripancreatic and mesenteric
adipose tissue. Histologically, necrotic fat cells are distinguishable as pale outlines, and
their cytoplasm is filled with an amorphous-appearing, faintly basophilic material
6. Caseous necrosis has features of both coagulative and liquefactive necrosis.
Typically, it occurs in the center of tuberculous granulomas, which contain a white or
yellow “cheesy” material (Latin caseum = cheese) that accounts for the name of this
lesion. Histologically, the outlines of necrotic cells are not preserved, but the tissue has
not been liquefied either. The remnants of the cells appear as finely granular,
7. Fibrinoid necrosis is characterised by deposition of fibrin-like material, which has
the staining properties of fibrin. It is encountered in various examples of immunologic
tissue injury, arterioles in hypertension, peptic ulcer etc. Histologically, fibrinoid
necrosis is identified by brightly eosinophilic, hyaline like deposition in the vessel‟s
wall or on the luminal surface of a peptic ulcer.
Outcomes of necrosis
Regeneration of tissues – replacement of the dead tissue with a new one.
Incapsulation – formation of the connective tissue capsula around necrotic area.
Organization – replacement of the dead tissue with connective tissue.
Petrification – replacement of the dead tissue with calcium salts.
Incrustation – replacement of the dead tissue with any other salts except calcium.
Ossification – the formation of the bone tissue in the necrotic area;
Hyaline change – the appearance of the hyaline-like substance in the necrotic area.
Suppuration or purulent fusion of necrotic tissues.
Sequestration – formation of sequester.
Mutilation – spontaneous tearing- away of the dead tissue.
Apoptosis is a programmed (physiological) death of the cell in the living body.
Morphologic features of apoptosis:
1. Cell shrinkage;
2. Chromatin condensation;
3. Formation of cytoplasmic blebs and apoptotic bodies;
4. Phagocytosis of apoptotic cells or bodies.
Histologically, in tissues stained with hematoxylin and eosin, apoptotic involves single cells
or small clusters of cells.
The apoptotic cell appears as a round or oval mass of intensely eosinophilic cytoplasm with
dense nuclear chromatin fragments.
Because the cell shrinkage and formation of the apoptotic bodies are rapid, however, and
the fragments are quickly phagocytosed, degraded, or extruded into the lumen,
considerable apoptosis may occur in tissue before it becomes apparent in histologic
sections. In addition, apoptosis - in contrast to necrosis - does not elicit inflammation,
marking it even more difficulty to detect histologically.
The contrasting features of apoptosis and necrosis are summarised in Table 2.
TABLE 1. Contrasting features of two main forms of gangrene
More common in bowel
More commonly venous obstruction
less often arterial occlusion
Organ dry shrunken and black
Part moist soft swollen rotten and
Limited due to very little blood Marked due to stuffing of organ with
of Present at the junct on between No clear line of demarcation
demarcation healthy and gangrenous part
Bacteria fail to survive
little Generally poor due to profound
TABLE 2. Contrasting Features of Apoptosis and Necrosis
Programmed and coordinated cell Cell death along with degradation of
tissue by hydrolytic enzymes
pathologic Hypoxia, toxins
3. Morphology No Inflammatory reaction
Inflammatory reaction always present
Death of single cells
Death of many adjacent cells
Cell swelling initially
Cytoplasmic blebs on membrane
Phagocytosis of apoptotic bodies by Phagocytosis
4. Molecular Lysosomes and other organelles Lysosomal breakdown with liberation
DEATH, SIGNS OF DEATH, POSTMORTEN CHANGES
Death is the expression of irreversible stopping of the vital activity of organism. With
approach of death a man turns into the dead body or corpse (cadaver).
There are natural (physiologic), violent death and death after diseases.
Natural death takes place in senile persons as a result of physiologic wear of organism.
Violent death is a result of murders, suicides, traumas and accidents.
Death after diseases is a result of incompatibility of the life with changes that were
provoked by pathological (unhealthy) processes.
There are clinical and biological death:
1. Clinical death is characterized with stopping of breathing and blood circulation, which are
reversible during some minutes (the time of outliving of the brain cortex). Agony precedes clinical
death and is the result of uncoordinated actions of homeostatic systems during terminal period
(arrhythmia, paralysis of sphincters, convulsions and pulmonary edema).
2. Biological death is irreversible changes of vital activity of organism and beginning of autolytical
processes. The central nervous system dies in the fiirst 5-6 minutes. In other organs and tissues this
process lengthen out to some hours or even days.
Soon after biological death a number of signs of death and postmorten changes appears. They
are the followings:
coolness of the dead body (algor mortis) develops as the result of stopping of
warnth‟s production in the body and equilization of temperature of dead body and
becoming numb of a corpse (rigor mortis) is manifested as condensation of
arbitrary and nonarbitrary muscles because of disappearing of adenosine triphosphate and
accumulation of lactic acid in them. Usually it develops in 2-5 hours after death, spreads to
all muscles of the body to the end of the first day, is kept during 2-3 days and then
putrid drying appears because of evaporation of moisture from the surface of the body. It
may be localized or generalized (mummification). The dimness of cornea and appearance of
dark-brown patches on sclera are connected with this process;
redistribution of blood in the corpse results in repletion of veins with blood, but
arteries remain almost empty. The postmorten coagulation of veins and cavities of the right
part of the heart takes place. However in the cases of death because of asphyxia the blood
does not coagulate (asphyxia of newborns);
putrid patches appear because of redistribution of blood in the corpse and depend on its
position. The blood flows down into the veins of the lower parts of the body and
accumulates their. That‟s why putrid hypostases appear in 3-6 hour after death;
putrifacation of the corpse is connected with processes of autolysis and rotting of the
corpse. Postmorten autolysis appears earlier and is more expressed in glandular organs
which cells are rich in proteolytic enzymes (liver, pancreas, stomach). Patrifacative
processes join quickly to postmorten autolysis because of proliferation of putrifactive
bacteria. Putrifacation intestifies postmorten autolysis, leading to fusion of tissues which
become to be colored in dirty-green color and exhale characteristic putrid smell. Quickness
of corpse‟s aulotysis and putrifacation depends on the temperature of environment.
For the sake of survival on exposure to stress, the cells make adjustments with the changes in
their environment (i. e. adapt). Broadly speaking, such physiologic and pathologic adaptations occur
Decreasing or increasing their size (atrophy and hypertrophy respectively).
By changing the pathway of phenotypic differentiation of cells (metaplasia and dysplasia).
In general, the adaptive responses are reversible on withdrawal of stimulus.
Atrophy means reduction of the number and size of cells, tissues and organs in living
organism characterized by decrease or stopping their function.
Atrophy may be physiologic and pathologic.
A. Physiologic atrophy. It is a normal process of aging in some tissues:
1. Atrophy of lymphoid tissue in lymph nodes, appendix and thymus.
2. Atrophy of gonads after menopause.
3. Atrophy of brain.
4. Atrophy of bones.
It may be obliteration of the umbilical arteries and arterial duct (Botallow‟s) after birth.
B. Pathologic atrophy may be general and local.
General atrophy is observed in cachexia due to
Oncologic and chronic diseases.
Injury of hypophysis (endocrine cachexia).
Injury of hypothalamus (cerebral cachexia).
Gross appearance of patients occurs:
Adipose tissue is decreased and it has brown color.
Muscles are atrophied; skin is dry and flabby.
Internal organs are small, brown color and often shrunken.
Osteoporosis takes place.
Cells become smaller in size but are not dead cells.
Shrinkage in cell size is due to reduction in cell organelles.
Accumulation of lipofuscin around nucleus takes place. Lipofuscin (“wear and tear”
pigment) is a golden yellow pigment representing undigested lipid material derived from
Local atrophy has several types:
1. Ischemic atrophy develops due to insufficiency of the blood supply. Hypoxia stimulates of the
proliferation of fibroblasts and forms sclerosis. For example: small atrophic kidney in atherosclerosis
of renal artery, atrophy of brain in cerebral atherosclerosis.
2. Disuse atrophy (dysfunctional) develops due to reduction of the function of organ: atrophy of
muscles due to immobility, atrophy of the pancreas in obstruction of pancreatic duct.
3. Neuropathic atrophy due to interrupted nerve supply: poliomyelitis, motor neuron disease, nerve
section, and inflammation of facial nerve.
4. Endocrine atrophy: hypopituitarism may lead to atrophy of thyroid, adrenal and gonads;
hypothyroidism may cause atrophy of the skin and its adnexal structures.
5. Pressure atrophy: compression of spine by tumor in nerve root, compression of skull by
meningioma arising from pia-arachnoid, compression of sternum by aneurysm of arch of aorta,
compression of renal tissue by dilated renal pelvic in hydronephrosis, compression of brain tissue by
dilated ventricles in hydrocephalus.
6. Atrophy due to chemical and physical influences. For example: action of the radiation lead to
atrophy of bone marrow and genital organs.
7. Idiopathic atrophy: myopathies, testicular atrophy.
The atrophic tissue may be replaced by fatty ingrowths. Atrophy is reversible provided the cause is
eliminated or deficiencies restored.
Hypertrophy and hyperplasia
Hypertrophy refers to an increase in the size of parenchymal resulting in enlargement of the
organ or tissue, without any change in the number of cells.
Hyperplasia is an increase in the number of parenchymal cells resulting in enlargement of
the organ or tissue. Quite often, both hyperplasia and hypertrophy occur together.
Mechanisms of hypertrophy
Hypertrophy of tissue arises due to increase of size of functional cells. Thus, the
hypertrophied organ has no new cells, just larger cells.
Hypertrophy of tissue arises due to increase of number of functional cells (hyperplasia of
Hypertrophy of cells arises due to both increase of size of functional cells and increase of
number of ultrastructural elements. Thus, the increased size of the cells is due not to an
increased intake of fluid, called cellular swelling or edema, but to the synthesis of more
structural components. It is called true hypotrophy.
False hypertrophy is the increase of the size of organs due to growth of connective
tissue, accumulation of the fluid or fatty tissue. It results in atrophy of organ
(hydronephrosis, hydrocephalus, obesity of heart).
True hypertrophy (hyperplasia) has adaptative and compensative characteristics and may
be physiologic and pathologic:
A. Physiologic hypertrophy (hyperplasia).
1. Neurogumoral (hormonal) hypertrophy: hypertrophy of female breast at puberty,
during pregnancy and lactation, hypertrophy of pregnant uterus, proliferative activity
of normal endometrium after a normal menstrual cycle, prostatic hyperplasia in old
2. Working hypertrophy of skeletal muscle: hypertrophied muscles in athletes and
B. Pathologic hypertrophy (hyperplasia).
1. Neurogumoral hypertrophy develops due to impairment of endocrine functions.
Endometrial glandular hyperplasia following estrogen excess which it occurs by
metrorrhagia; atrophy of testis leads to increase of breast (gynecomastia);
hyperfunction of anterior lobus hypophisis (adenoma) leads to increase skeleton
2. Working hypertrophy develops in tissues consisting of stable undivided cells due to
increase of size it one. It may be often in cardiac muscle at some cardiac diseases, such
as: systemic hypertension, aortic valve disease (stenosis and insufficiency), mitral
insufficiency; hypertrophy of smooth muscle: cardiac achalasia (in esophagus), pyloric
stenosis (in stomach), and intestinal stricture; hypertrophy of urine bladder in
adenoma of prostatic glands.
3. Compensatory reparative hypertrophy: regeneration of the liver following partial
hepatectomy, regeneration of epidermis after skin abrasion; hypertrophy of
myocardium in postinfarctional cardiosclerosis.
4. Vicarious (substitutional) hypertrophy: following nephrectomy on one side in a
young patient there is compensatory hypertrophy as well as hyperplasia of the
nephrons of the other kidney.
5. Hypertrophic vegetations develop due to chronic inflammation in mucous
membranes (polyps and condilomas); lymphostasis leads to ingrowth of connective
tissue, examples of false hypertrophy. In wound healing, there is formation of
According to stage of adaptation two types of myocardial hypertrophy have been described:
Concentric. In concentric hypertrophy (clinically, no insufficiency) the musculature is
clearly enlarged, measuring till 1.8 cm, but chambers of the heart are not dilated.
Eccentric. In eccentric hypertrophy myocardium is enlarged but chambers of the heart are
dilated. This leads to hemodynamic disorder with cardiac insufficiency. It is called
The affected organ is enlarged and firm. For example: a hypertrophied heart of a patient with
systemic hypertension may weight 700-800 g as compared to average normal adult weight of 350 g.
There is enlargement of muscle fibers as well as of nuclei. At ultrastructural level, there is increased
Metaplasia is defined as a reversible change of one type to another type of adult epithelial or
mesenchymal cells, usually in response to abnormal stimuli, and often reverts back to normal on
removal of stimulus. Metaplasia is broadly divided into 2 types:
A. Epithelial metaplasia. This is the more common type. The metaplastic changes may be patchy or
diffuse and usually result in replacement by stronger but less well-specialized epithelium. Some
common types of epithelial metaplasia following:
Squamous metaplasia: in bronchus in chronic smokers, in uterine endocervix in
prolapse of the uterus and in old age, in gall bladder in chronic cholecystitis with
cholelithiasis, in prostate in chronic prostatitis and estrogen therapy, in renal pelvis and
urinary bladder in chronic infection and stones; in vitamin A deficiency, apart from
xerophthalmia, there is squamous metaplasia in the nose, bronchi, urinary tract, lacrimal
and salivary glands.
Columnar metaplasia in which there is transformation to columnar epithelium:
intestinal metaplasia in healed chronic gastric ulcer, conversion of pseudostratified
columnar epithelium in chronic bronchitis and bronchiectasis to columnar type, in cervical
B. Mezenhymal metaplasia. Less often, there is transformation of one adult type of mesenchymal
tissue to another.
Osseous metaplasia. Osseous metaplasia is formation of bone in fibrous tissue, cartilage
or myxoid tissue: in arterial wall in old age, in soft tissues in myositis ossificans, in cartilage
of larynx and bronchi in elderly people, in scar of chronic inflammation of prolonged
duration, in the fibrous stroma of tumor.
Cartilaginous metaplasia. In healing of fractures, cartilaginous metaplasia may occur
where there is undue mobility.
Dysplasia means “disordered cellular development”, often accompanied with metaplasia and
hyperplasia, it is therefore also referred to as atypical hyperplasia. Epithelial dysplasia is
characterized by cellular proliferation and cytological changes, which include:
Hyperplasia of epithelial layers.
Disorderly arrangement of cells from basal layer to the surface layer.
Cellular and nuclear pleomorphism.
Increased nucleocytoplasmic ratios.
Increased mitotic activity.
The two most common examples of dysplastic changes are the uterine cervix and
Healing is the body response to injury in an attempt to restore normal structure and function.
The process of healing involves 2 distinct processes:
Complete regeneration (restitution), denoting the replacement of injured cells by
cells of the same type, sometimes leaving no residual trace of the previous injury, and
Incomplete regeneration (substitution) or replacement by connective tissue, or
fibroplasia, which leaves a permanent scar. In most instances, both processes contribute to
repair. In addition, both regeneration and fibroplasia are determined by essentially similar
mechanisms involving cell migration, proliferation, and differentiations, as well as cellmatrix interactions.
Depending upon their capacity to divide, the cells of the body can be divided into 3 groups:
Labile cells. These cells continue to multiply throughout life under normal physiologic
conditions. These include: surface epithelial cells of epidermis, alimentary tract, respiratory
tract, urinary tract, vagina, cervix, uterine endometrium, hematopoietic cells of bone
marrow and cells of lymph nodes and spleen.
Stable cells. These cells decrease or lose their ability to proliferate after adolescence but
retain the capacity to multiply in response to stimuli throughout adult life. These include:
parenchymal cells of organs like liver, pancreas, kidneys, adrenal and thyroid;
mesenchymal cells like smooth muscle cells, fibroblasts, vascular endothelium, bone and
Permanent cells. These cells lose their ability to proliferate around the time of birth.
These include: neurons of nervous system, skeletal muscle and cardiac muscle cells.
Cellular: bones, epidermis, mucous membrane, connective tissue, endothelium,
hemopoetic system, and limfoid tissue.
Intracellular: myocardium, skeletal muscles, ganglious cells and central nervous system
Mixed: liver, kidneys, lungs, pancreas, endocrine organs, smooth muscles, vegetative
nervous system (VNS).
1. Physiological regeneration is the process of replacement that occurs due to physiologic necrosis
2. Reparative regeneration (complete, incomplete with regenerative hypertrophy) is the regeneration
after some pathologic necrosis.
3. Pathologic regeneration is the slow (hyporegeneration) or pathologically absence one,
hyperregeneration or metaplasia (change in cell type).
Repair is the replacement of injured tissue by fibrous tissue. Two processes are involved in
1. Granulation tissue formation.
2. Contraction of wounds.
Repair response takes place by participation of mesenchymal cells (consisting of connective
tissue stem cells, fibrocytes and histiocytes), endothelial cells, macrophages, platelets, and the
parenchymal cells of the injured organ.
Granulation tissue formation
The following 3 phases are observed in the formation of granulation tissue.
1. Phase of inflammation. There is acute inflammatory response with exudation of plasma,
neutrophils and some monocytes within 24 hours.
2. Phase of clearance. Combination of proteolytic enzymes liberated from neutrophils, autolytic
enzymes from dead tissues cells, and phagocytic activity of macrophages clear of the necrotic tissue,
debris and red blood cells.
3. Phase of ingrowth of granulation tissue. This phase consists of 2 main processes: angiogenesis or
neovascularisation and formation of fibrous tissue.
Angiogenesis (neovascularisation). Formation of new blood vessels at the site of injury
takes place by proliferation of endothelial cells from the margins of severed blood vessels. The process
of angiogenesis takes place under the influence of the following:
1. Endothelial cell growth factors.
2. Some components of matrix like type IV collagen.
Fibrous tissue formation. The new fibroblasts originate from fibrocytes as well as by
mitotic division of fibroblasts. Some of these fibroblasts have morphologic and functional
characteristics of smooth muscle cells (myofibroblasts). Collagen fibrils begin to appear by about 6th
day. As maturation proceeds, more and more of collagen is formed while the number of active
fibroblasts and new blood vessels decreases. This results in formation of inactive looking scar known
Contraction of wounds. The wound starts contracting after 2-3 days and the process is
completed by the 14th day. In order to explain the mechanism of wound contraction, a number of
factors have been proposed:
1. Dehydration as a result of removal of fluid.
2. Contraction of collagen.
3. Discovery of myofibroblasts.
Healing of skin wounds provides a classical example of combination of regeneration and
repair described above.
Two types of factors influence the wound healing: those acting locally and those acting in
Local factors: infection, poor blood supply to wound, foreign bodies including sutures
interfere with healing and cause intense inflammatory reaction and infection; exposure to
ionizing radiation; exposure to ultraviolet light; type, size and location of injury.
Systemic factors: age, nutrition, systemic infection, uncontrolled diabetes, hematological
This can be accomplished in one of the following two ways:
1. Healing by first intention (primary union).
2. Healing by second intention (secondary union).
Healing by first intention (primary union)
This is defined as healing of a wound, which has the following characteristics:
Clean and uninfected.
Without much loss of cells and tissue.
Edges of wound are approximated by surgical sutures.
The sequence of events in primary union is described below:
1. Initial hemorrhage. Immediately after injury, the space between the approximated
surfaces of incised wound is filled with blood, which then clots and seals the wound
against dehydration and infection.
2. Acute inflammatory response. This occurs within 24 hours with appearance of
3. Epithelial changes. The basal cells of epidermis from both the cut margins start
proliferating and migrating towards incisional space in the form of epithelial spurs.
4. Organization. By 3rd day, fibroblasts also invade the wound area. By 5th day, new
collagen fibrils start forming. In 4 weeks, the scar tissue with scanty cellular and
vascular elements, a few inflammatory cells and epithelialised surface is formed.
5. Suture tracks. Each suture track is a separate wound and incites the same
phenomena as in healing of the primary wound.
Healing by second intention (secondary union)
This is defined as healing of a wound having the following characteristics:
Open with a large tissue defect, at times infected.
Having extensive loss of cells and tissues.
The wound is not approximated by surgical sutures but is left open.
The sequences of events in secondary union are as under:
Inflammatory phase. There is an initial acute inflammatory response followed by
appearance of macrophages, which clear off the debris as in primary union.
Epithelial changes. As in primary healing, the epidermal cells from both the margins of
wound proliferate and migrate into the wound in the form of epithelial spurs.
Granulation tissue. The main bulk of secondary healing is by granulations. Granulation
tissue is formed by proliferation of fibroblasts and neovascularisation from the adjoining
Wound contraction. Contraction of wound is an important feature of secondary healing, not
seen in primary healing.
Presence of infection. Bacterial contamination of an open wound delays the process of
healing due to release of bacterial toxins that provoke necrosis, suppuration and
Complications of Wound Healing
Implantation (epidermal) cyst.
Deficient scar formation.
Hypertrophied scars and keloid formation.
These are considered 2 broad headings
Disturbances in the volume of the circulating blood. These include hyperemia and
congestion, hemorrhage and shock
Circulatory disturbances of obstructive nature. These are thrombosis, embolism,
ischemia and infarction.
Hyperemia and congestion
Hyperemia and congestion are the terms used for increased volume of blood within dilated
vessels of an organ or tissue the increased volume from arterial and arteriolar dilatation being
referred to as hyperemia or active hyperemia, whereas the impaired venous drainage is called
venous congestion or passive hyperemia. The capillaries and veins are dilated paralytically
and filled with blood.
Arterial or active hyperemia is caused by an increased supply of blood from arterial
system. The affected tissue or organ is pink or red in appearance (erythema).
I. Common arterial or active hyperemia is a result
Of increasing volume of circulating blood (pletora).
Of increasing of amount of erythrocytes.
Vacatic (lat. – vacuum) because of decreased atmospheric pressure.
II. Local arterial hyperemia can be
Angioneurotic – because of dilatation of arteries and arterioles.
Hyperemia after anemia.
In arterio-venous fistula.
Venous, or passive hyperemia, or congestion is caused by impediment to the exit of
blood through venous pathway. The dilatation of veins and capillaries due to impaired venous
drainage results in passive hyperemia or venous congestion, commonly referred to as congestion.
Congestion may be acute or chronic, the latter being more common and called chronic venous
I. Common congestion or Systemic (General) venous congestion is engorgement of systemic veins.
It can be a result of
left-sided and right-sided heart failure
diseases of the lungs which interfere with pulmonary blood flow, like pulmonary fibrosis,
II. Local congestion can be a result of
venous obstruction because of its thrombosis,
compression of venous vessel with tumor or ingrowth of connective tissue,
development of collateral blood circulation.
Morphology of congestion
Because of the increase in venous blood, organs become swollen and purplish. With long
continued over-distension, the wall of the venules shows reactive thickening and there is mild
intestinal fibrosis of the organs, giving them a very firm consistency. These changes are seen typically
in the kidney and spleen. Important additional changes are found in the lungs and liver.
Lungs. The lungs are burcly, congested and brownish in color. Pulmonary venous
engorgement leads to alveolar hemorrhage. Hemoglobin from intra-alveolar blood is transformed into
hemosiderin, which is then phagocytized by macrophages. These macrophages are known as heart
failure cells. Phagocytes full of brown pigment migrate into intestinal tissue and to the lymph nodus.
The sectioned surface is dark brown. It process in lungs is named as “brown induration” of the
Spleen. Chronic venous congestion of the spleen occurs in right heart failure and in portal
hypertension from cirrhosis of liver. The spleen in early stage is moderately enlarged while in longstanding cases there is progressive enlargement and may weigh up to 500 g to 1000 g. The organ is
deeply congested, tense and cyanotic (“cyanotic induration of the spleen”). Sectioned surface is
gray tan. The red pulp shows congestion and marked sinusoidal dilatation with areas of recent and old
hemorrhages. These hemorrhages may get organized. This advanced stage seen more commonly in
hepatic cirrhosis is called congestive splenomegaly and is the commonest cause of
Liver. Chronic venous congestion of the liver occurs in right heart failure and sometimes due
to occlusion of inferior vena cava and hepatic vein. The liver is enlarged and tender and the capsule is
tense. Cut surface shows characteristic “nutmeg liver” due to red and yellow mottled appearance.
The changes of congestion are more marked in the centrolobular zone due to severe hypoxia than in
the peripheral zone. The centrolobular hepatocytes undergo degenerative changes, and eventually
centrolobular hemorrhagic necrosis may be seen. The peripheral zone of the lobule is less
severely affected by chronic hypoxia and shows some fatty change in the hepatocytes. If the patient
has periods of remission, the remaining liver cells may undergo compensatory hyperplasia. This
results in small, irregular, pale nodules alternating with areas of fibrosis – so-called cardiac cirrhosis.
It‟s not true cirrhosis and does not causes hepatic failure.
Outcomes of congestion:
Induration of organs.
Atrophy of organs.
Hemorrhage (i.e. bleeding) is a discharge of blood from the vascular compairtment to the
exterior of the body or into nonvascular body spaces.
Mechanisms of hemorrhages
1. By destruction of the blood vessel‟s wall (f.e. trauma, rupture of aneurysm).
2. By diapedesis of erythrocytes because of the increased permeability of the vascular wall (f.e.
3. By ulceration of the vessel‟s wall (f.e. ulcer of stomach, necrosis of tumor, pulmonary tuberculosis).
Thus a severe decrease in the number of platelets (thrombocytopenia) or a deficiency of a
coagulation factor (e.g., factor VIII in hemophylia) is assosiated with spontaneous hemorrhages
unrelated to any apparent trauma.
Types of hemorrhages according to the site of origin
1. Cardiac, as following a penetrating heart wound.
2. Arterial, due to trauma and rupture of a dissecting aneurysm.
3. Capillary, which is usually due to trauma, inherent vessel wall weakness, or a coagulation defect.
4. Venous, which is usually caused by trauma or surgical operation, from esophageal varices.
Types of internal hemorrhages
Petechia – a small mucosal or serosal hemorrhage or minute punctate hemorrhage usually
in the skin or conjunctiva.
Purpura or hemorrhagic infiltration - the accumulation of some erythrocytes in tissue
Ecchymoses or bruise - the superficial large extravasations of blood into the skin and
mucous membranes. Following a bruise in association with coagulation defect, an initially
purple discoloration of the skin turns green and then yellow before resolving, a sequence
that reflects the progressive oxidation of bilirubin released from the hemoglobin of
degraded of red blood cells. A good example of an eccxymosis is a “black eye”.
Hematoma - a grossly visible localized accumulation of the blood in the soft tissue.
Types of hemorrhages in body cavities
Hemothorax – hemorrhage in the pleural cavity.
Hemopericardium – hemorrhage in the pericardium cavity.
Hemoperitoneum – hemorrhage in the abdomen cavity.
Hemoarthrosis – hemorrhage in the joint cavity.
External hemorrhages may be such as:
Melena is deposition of the blood in the faces (excrement or stool) due to hemorrhage from
ulcer of stomach, polip or ulcer of intestines.
Hemoptyesis is hemorrhage from lungs.
Metrorrhagia is hemorrhage from uterus.
Outcomes of hemorrhages
Coagulation of the blood.
Organization and incapsulation of the hematoma.
Brown cystic formatiom (in cerebral hematoma due to accumulation of hemosiderin).
Purulent fusion of the hematoma.
In cases of death from acute massive hemorrhage, the most significant postmorten changes are
gross rather then microscopic and consists in generalized pallor of tissue, collapse of the great veins,
and a flabby, shrunken, gray spleen.
A sudden loss of 33% of blood volume may cause death, while loss of upto 50% of blood
volume over a period of 24 hours may not be necessarily fatal. However chronic blood loss generally
produces an iron deficiency anemia, whereas acute hemorrhage may lead to serious immediate
consequences such as hypovolemic shock.
Ischemia is a loss of blood supply, which occurs when arterial flow is impeded by
atherosclerosis or by thrombi, or by some other causes. Ischemia is the most common cause of
Types of ischemia
Because of redistribution of blood.
The primary response of acute ischemia is cellular swelling or edema with dilation of the
endoplasmic reticulum, dissociation of polysomes into monosomes, swelling of
mitochondria, and also increased concentration of water, sodium, and chloride and
decreased concentration of potassium into the cytoplasm. If the duration of ischemia is
short, the structure and the function of tissue may be restored.
If ischemia persists, irreversible injury ensures with severe vacuolization of the
mitochondria including their christae, extensive damage to cytoplasm membranes, and
swelling of lysosomes. When the lesion is continuous, infarction, atrophy or sclerosis may
Infarction is an area of ischemic necrosis within a tissue or an organ, produced by occlusion of
either its arterial supply or its venous drainage.
Types of infarctions:
Ischemic (white) infarction is encountered with arterial occlusion and in solid tissues
Red (hemorrhagic) infarction is encountered with venous occlusion, in tissue as with
double circulation, and in tissue previously congested (lung, intestinum).
White infarction with hemorrhagic halo (kidneys, heart).
According to their age, infarcts are classified as:
Recent or fresh.
Old or healed.
According to the propagation it may be
Total (when the whole organ is affected).
Subtotal (when only a part of the organ is affected).
Microinfarct (when observed only microscopically).
The process of infarction takes place as follows:
Localised hyperemia due to local anoxemia.
Within a few hours, the affected part becomes swollen due to edema and hemorrhage.
Cellular changes such as cloudy swelling and degeneration appear early.
There is progressive autolysis of the necrotic tissue and hemolysis of the red cells.
An acute inflammatory reaction and hyperemia appear at the same time in the surrounding
Blood pigments, hematoidin and hemosiderin, liberated by hemolysis is deposited in the
Following this, there is progressive ingrowth of granulation tissue from the margin of the
Myocardial infarction usually develops due to thrombosis of coronary artery. This
infarction shows coagulative necrosis of myocardial cells. Almost no blood is seen in the vessels. The
nuclei of muscle‟s fibers and stroma cells are absent. The peripheral portion of the infarction has been
invaded by acute inflammatory cells, which act as scavengers and remove the dead cells.
It is white infarction with hemorrhagic halo. It is classically irregular shape with hemorrhagic
Infarction of the lungs. Embolism of the pulmonary arteries may produce pulmonary
infarction, though not always. The pulmonary infarcts are classically wedge-shaped with base on the
pleura, hemorrhagic, variable in size, and most often in the lower lobes. Fibrinous pleuritis usually
covers the area of infarct. Cut surface is dark purple and may show the blocked vessel near the apex of
the infarcted area. Old organized and healed pulmonary infarcts appear as retracted fibrous scars. The
characteristic feature is coagulative hemorrhagic necrosis of the alveolar walls.
Renal infarction is common, found in upto 5% of autopsies. Renal infarcts are often
multiple and may be bilateral. Characteristically, they are pale or anemic and wedge-shaped with base
resting under the capsule and apex pointing towards the medulla. Generally, a narrow rim of
preserved renal tissue under the capsule is spared because it draws its blood supply from the capsular
vessels. The affected area shows characteristic coagulative necrosis of renal parenchyma i.e. there are
shadows of renal tubules and glomeruli without intact nuclei and cytoplasmic content.
Infarction of the spleen is one of the common sites for infarction. Splenic infarction results
from occlusion of the splenic artery or its branches. Splenic infarcts are often multiple. They are
characteristically pale or anemic and wedge-shaped with their base at the periphery and apex pointing
towards hilum. Coagulative necrosis and inflammatory reaction are seen.
Occlusion of an artery or vein may have little or no effect on the involved tissue or it may cause
death of the tissue and, indeed, of the individual. The major determinates include:
The nature of the vascular supply.
The rate of development of the occlusion.
The vulnerability of the tissue to hypoxia.
Clinical significance of infarction
Most of the cardiovascular deaths result from myocardial and cerebral infarction. Pulmonary
infarction is an extremely common complication in a variety of clinical settings. Ischemic necrosis
(gangrene) of the lower extremities is a relatively unusual clinical problem in the population at large
but is a major concern in diabetes melitus.
Stasis (stasis - stop) is arrest of blood flow in the vessels of microcirculatory system
(capillaries). The capillaries and veins are dilated paralytically and filled with blood. In the lumen of
some capillaries the homogenous eosinophilic masses can be seen. They are columns of erythrocytes
sticked together, which is called prestasis. Sludge syndrome (phenomenon) is regarded as a type of
stasis. It is characterized by sticking of erythrocytes, leukocytes and thrombocytes to each other,
which is accompanied by blood viscosity increase.
Stasis may be discirculatory as a result of venous hyperemia or ischemia. Causes of stasis:
Physical factors (temperature elevation, cold).
Short stasis is reversible, long one causes hyaline thrombi formation, vascular permeability
increase, edema, bleeding.
Isolated vein spasm may cause leukostasis, accumulation of erythrocytes within venules (small
veins) and capillaries. It is observed in hypoxia. In shock, leukostasis may be generalized, but as a rule
it is localized in the venules.
Microcirculation disturbances. There are four links in microcirculation:
1. The link of inflow and distribution of the blood (arterioles and precapillaries).
2. Intermediate (exchange) link (capillaries).
3. Depot link (postcapillaries and venules).
4. Drainage link (lymphatic capillaries and postcapillaries). The function of
microcirculation is exchange between the blood and tissue. Pathology of
microcirculatory system is formed of vascular, intravascular and extravascular
Vascular changes are those in the thickness and shape of the vessels, angiopathies with
disturbance of vascular permeability as a result of hypoxia.
Intravascular changes manifest as different disturbances of blood rheology (sludge, prestasis,
stasis). They are observed in shock of different origin.
Extravascular changes are perivascular edema, hemorrhage, lymphostasis on the lymph
Thrombosis is a pathologic process, which denotes the formation of a clotted mass of blood
within the noninterruptured vascular system.
Influences predisposing to thrombosis:
1. Injury to endothelium;
2. Alterations in the normal blood flow;
3. Alterations in the blood coagulation system (hypercoagulability).
Mechanisms of formation
Agglutination of platelets. Platelets adhere to the endothelium and to each other forming a
Agglutination of erythrocytes. If the rate of the blood flow is slow, as in veins, red cells are
entangled so that the lumen is occluded;
Coagulation of fibrinogen. In front and behind the platelet mass the blood stagnates.
Further formation of fibrin takes place resulting in a large solid coagulum. The thrombus
extends in either direction to the nearest junction;
Precipitation of plasma proteins. With a slow blood flow in the joining vessel more fibrin is
formed by the platelets at the tip of the thrombus, thus occluding the joint vessel. Blood
stagnates in the joining vessel and thrombosis forwards to the next joining vessel. There
may be a succession of thrombotic episodes – a propagating thrombus.
Types of thrombi
According to the degree of the lumen obstruction, thrombi may be:
Occlusive thrombi most commonly develop in small arteries and veins.
Wall-attached or parietal thrombi develop in large arteries and heart cavities.
Globe-shaped (in the heart).
According to the morphology
Thrombi may be of various shapes, size and composition depending upon the site of origin and
it is attached to the vascular wall; it is dense, with corrugated surface. It is composed of branching
bars of stuck thrombocytes and bands of fibrin with erythrocytes and leukocytes located between
Morphological types of thrombi
White thrombus – consists mainly of platelets, fibrin and leukocytes; forms slowly in
rapid circulation of the blood (usually in the arteries);
Red thrombus – consists of platelets, fibrin and excessive amount of erythrocytes; forms
rapidly at slow blood circulation (usually in veins). Venous thrombi are dark-red colored
dry masses with dim surface.
Mixed or laminated thrombus – has laminated structure, contains white and red
elements of thrombus (usually forms in veins, aneurysms of aorta and heart). Mixed