1. Pathology of extracellular
matrix and connective
tissue
Dr. Radina IvanovaDr. Radina Ivanova
Associate Professor of PathologyAssociate Professor of Pathology
Medical University of SofiaMedical University of Sofia

2. Pathology of extracellular matrix
and connective tissue
 Abnormal accumulations in the extracellular
matrix – types.
 Disorders in the metabolism and structure of the
collagen.
 Disorders in the content of the proteoglycans.
 Fibrinoid change in the extracellular matrix.
 Hyaline change in the extracellular matrix.

3. Pathology of extracellular matrix
and connective tissue
 Amyloid deposition in the extracellular matrix.
Types of amyloidosis.
 Generalized systemic amyloidosis.
 Localized amyloidosis. Special staining
methods. Tincture properties of the amyloid.
 Morphology of amyloid deposition.
 Deposition of calcium in the extracellular
matrix.
 Deposition of urates in the extracellular matrix.

4. Extracellular matrix
 It consists of:
 the interstitial matrix between cells
 basement membranes underlying epithelia and surrounding
vessels
 The ECM serves several important functions:
 It provides mechanical support to tissues (collagens and elastin)
 It acts as a substrate for cell growth and the formation of tissue
microenvironments
 It regulates cell proliferation and differentiation

proteoglycans bind growth factors and display them at high
concentration, and fibronectin and laminin stimulate cells via cellular
integrin receptors
 An intact ECM is required for tissue regeneration

if the ECM is damaged, repair can only be accomplished by scar
formation.

5. Extracellular matrix
 3 basic components of ECM
 fibrous structural proteins such
as collagens and elastins, which
confer tensile strength and recoil

fibrillar and nonfibrillar

BM - nonfibrillar collagen type IV
 water-hydrated gels such as
proteoglycans and hyaluronan,
which permit lubrication

glycosaminoglycans (dermatan
sulfate and heparan sulfate)
 adhesive glycoproteins that
connect the matrix elements to
one another and to cells

fibronectin
 Laminin

Integrins

6. Abnormal accumulations in the
extracellular matrix - types.
 Disorders in the metabolism and structure of the
collagen.
 Disorders in the metabolism and structure of the
elastins.
 Disorders in the content of the proteoglycans
 Abnormal accumulations in the ECM
 Proteins

Fibrinod

Hyalin

Amyloid
 Inorganic substances

Ca

Urates

7. Disorders in the metabolism
and structure of the collagen
 Increased collagen synthesis (fibrosis)
 Abnormal structure of collagen
 Abnormal collagenolysis

8. Increased collagen synthesis
 = Fibrosis (sclerosis)
 Fibroblasts, myofibroblasts,
smooth mucle cells
 Van Gieson – collagen - red
 ↑ activity of lysyl-oxidase
 Types
 Substitutive

Heart - cicatrix post MI

Liver cirrhosis – chronic hepatitis
 Intestitial

Pulmo – in chronic left-sided
heart failure (induratio fusca
pulmonis)

9. Abnormal structure of collagen
 Genetic defects in collagen structure
 Marfan’s syndrome
 Ehlers-Danlos syndrome

10. Marfan’s syndrome
 Autosomal dominant disorder of connective tissues, the basic
biochemical abnormality affects fibrillin 1.
 Which is the major component of microfibrils found in the
extracellular matrix, component of elastins
 Mutations in the FBN1 gene, which maps to chromosome 15q21.
 Morphology
 Skeleton

Arachnodactyly, hyperextensibility of joints, spinal deformities, such as
kyphoscoliosis, deformed chest
 Eyes

bilateral dislocation or subluxation
 cardiovascular system

aneurysmal dilation and aortic dissection
 Regurgitation of mitral valve, congestive heart failure

11. Ehlers-Danlos syndromes
 There are six variants of Ehlers-Danlos syndromes, all
caused by defects in collagen synthesis or assembly
 30 distinct types of collagen, and all of them have characteristic
tissue distributions and are the products of different genes
 the clinical heterogeneity of EDS can be explained by mutations in
different collagen genes

Deficiency of the enzyme lysyl hydroxylase

Deficient synthesis of type III collagen resulting from mutations
affecting the COL3A1 gene

conversion of procollagen type I to collagen, resulting from a mutation
in two type I collagen genes (COL1A1 and COL1A2)
 Clinical features are:
 fragile, hyperextensible skin vulnerable to trauma
 hypermobile joints
 rupture of internal organs like colon, cornea, and large arteries
 Wound healing is poor

12. Abnormal collagenolysis
 ↑ activity of collagenlytic enzymes
 Collagenasess
 ↓ activity of anticollagenases
 α1- antitrypsin, β1-anticollagenase
 α1- antitrypsin defficiency
 an autosomal recessive disorder
marked by abnormally low serum levels
of this protease inhibitor

synthesized predominantly by
hepatocytes
 The AAT gene, chromosome 14,

very polymorphic, and at least 75 forms
have been identified

PiZZ genotype) have circulating AAT
levels that are only 10% of normal levels
 marked cholestasis with hepatocyte
necrosis in newborns, to childhood
cirrhosis, or to a chronic inflammatory
hepatitis
PAS stain of liver -red cytoplasmic granules

13. Disorders in the metabolism and
structure of the elastins
 Decreased elastogenesis
 Aging – wrinkles
 Ectasia of the aorta
 Senile emphysema
 Increased/abnormal elastogenesis=elastosis
 Senile elastosis –skin
 Endocardial fibroelastosis

Newborn – left heart ventriculus

Aged – right heart ventriculus, carcinoid syndrome

14. Disorders in the content of the
proteoglycans
 Impaired proteoglycans’ synthesis
 Abnormal collagen-proteoglycan
complexes

Free proteoglycans ⇒accumulate water⇒
tissue swelling ⇒ mucous appearance
 Localised

Pretibial myxedema – Bazedow’s disease
 Generalised

in myxedema (thyroid hypofunction), due to ↓
disposal of hondroit-sulfates
 Mucoviscidosis

15. Mucoviscidosis (cystic
fibrosis)
 Autosomal recessive defect, which leads to lack of a
membrane component essential to proper chloride
transport across membranes of the mucus-producing
exocrine glands and epithelium of respiratory,
gastrointestinal tract and pancreas
 CFTR, chromosome 7
 Viscous secretion in exocrine glands

The disease is named for changes in the pancreas and mucous
salivary glands, which have their ducts plugged by viscous mucus,
"Cysts" form behind the plugs, and "fibrosis" ensues after years of
obstruction.
 Clinical features

Pancreas and other exocrine glands (bile, duodenum)

Pulmo – the bronchial lumens become plugged by super-thick mucus,
there are often lung infections, pneumonias, lung abscesses,
bronchiectasis

sweat glands – salty sweat, (chloride is not reabsorbed through the
sweat ducts)

16. Mucoviscidosis pancreatis

17. Abnormal accumulations in the ECM
 Organic substances –mainly proteins
 Fibrinod
 Hyalin
 Amyloid
 Inorganic substances

Ca

Uric acid

18. Fibrinoid change in ECM
 Fibrinoid
 Morphologic description of non-structured substance

With various chemical composition, mainly plasma proteins
(albumin, globulins, fibrin)

Specific staining –positive reaction for fibrin (by Veigert), yellow –
by Van Gieson for fibrosis

Concomitant inflammatory reaction
 Fibrinoid necrosis
 In presence of necrotic cells
 Outcome - cicatrix

19. Fibrinoid change in ECM
 Finrinoid in precipitation of
immune complexes
 Systemic connective tissue
diseases

LE, rheumatoid arthritis,
scleroderma and others
 Localization

skin

different organs (ren, heart,
joints)

vessels
Rheumatoid arthritis-subcutaneous nodule
- Fibrinoid necrosis and inflammatory
reaction

20. Fibrinoid change in ECM
 Finrinoid in insudation of
plasma proteins
 Malignant hypertension

Endothelial cells of small
arteriae and arterioles

hyperplastic arteriolosclerosis
 Smooth muscle cell
hyperplasia and basement
membrane duplication
 Arterioles have an "onion
skin" appearance
Malignant nephrosclerosis
- Fibrinoid necrosis and inflammatory
reaction

21. Fibrinoid change in ECM
 Finrinoid in focal
mucosal necrosis
 Chronic peptic ulcer

Gastric/duodenal

Microscopy – 4 zones
 Debris
 Fibrinod necrosis
 Granulation tissue
 fibrosis

22. Hyaline change in the ECM
 Hyaline
 Morphologic description of non-structured
substance

With various chemical composition, mainly
proteins
 Hyalos - transparent, “glassy”

Staining –red by Van Gieson for fibrosis

No concomitant inflammatory reaction

23. Hyaline change in the ECM
Hyalinosis
 Connective tissue hyaline

Hyalinization of collagen
fibers in fibrosis

Non-structured, without cells,
homogenous, “glassy” tissue

Examples
 Cicatrices,
 tumors
 corpus albicans ovarii,
 glomeruronephritis
 lien Corpus albicans ovarii

24. Hyaline change in the ECM
Hyalinosis
 Vascular hyaline (hyaline
arteriolosclerosis)

DM
 due to nonenzymatic
glycosylation of proteins in the
basement membrane and its
leak into the vessel wall

Hypertension
 Increased intraluminal
pressure pushes plasma
proteins into the vessel wall.

Microscopy
 protein deposits in the vessel
wall, which occludes the lumen

25. Hyalinosis arteriolarum renis

26. Amyloid deposition in the ECM
 Amyloid
 Abnormal protein substance, which deposits among the
cells in various tissues and organs (amyloidosis)
 Microscopy – eosinophilic amorphous deposits, similar to
hyaline
 But with special stainings
 R. Virchov - the term amyloid (amyloss = starch)
 Tincture properties of the amyloid similar to the starch
 Cut organ is painted with iodine (red-brown) and sulfuric
acid (dark blue)
 amyloid binds a wide variety of proteoglycans and glycosaminoglycans
and the presence of abundant charged sugar groups give the deposits
staining characteristics that were thought to resemble starch

27. Amyloid deposition in the ECM
Special staining methods.
 Metilviolet and cresylviolet –
red staining (metachromasia)
 Congo red – red staining under
light microscopy
 Congo red - apple-green
birefringence under polarized
light
 Tioflavin S – yellow-green
fluorescence
 Immuhohistochemistry

28. Pathogenesis of amyloid deposition
 Amyloidosis is a disorder of protein misfolding
 Abnormal folding of normal or mutant proteins
 Amyloid is not a structurally homogeneous protein,
although it always has the same morphologic
appearance
 more than 20 (at last count, 23) different proteins can
aggregate and form fibrils with the appearance of
amyloid
 all amyloid deposits are composed of nonbranching
fibrils, 7.5 to 10 nm in diameter, each formed of β-sheet
polypeptide chains that are wound together
 Main types of amyloid proteins
 Amyloid light chain (AL)

Derived from light chains (e.g., Bence Jones protein)
 Amyloid-associated (AA)

Derived from serum associated amyloid (SAA), an acute
phase reactant
 β-Amyloid (Aβ)

Derived from amyloid precursor protein (protein product of
chromosome 21)
 Endocrine amyloid (AE)

29. Pathogenesis of amyloid deposition
 The deposition of these
proteins may result from:
 excessive production of
proteins that are prone to
misfolding and
aggregation
 mutations that produce
proteins that cannot fold
properly and tend to
aggregate
 defective or incomplete
proteolytic degradation of
extracellular proteins

30. Types of amyloidosis
 Amyloidosis is a condition associated with a number of inherited and
inflammatory disorders in which extracellular deposits of fibrillar proteins
are responsible for tissue damage and functional compromise.

Generalized Systemic

Primary amyloidosis (AL amyloid disposition, associated with multiple myelomas)

Secondary (reactive) - AA amyloid, associated with chronic inflammation (e.g.,
rheumatoid arthritis, tuberculosis)

Hereditary (autosomal recessive disorder involving AA amyloid (e.g., familial
Mediterranean fever)

Localized (confined to a single organ, e.g., brain)

31. Generalized systemic
amyloidosis
 Primary amyloidosis

AL amyloid disposition

Associated with immunocyte dyscrasias- multiple myeloma (30% of
cases), some B-cell lymphomas
 Secondary (reactive)

AA amyloid

Associated with chronic inflammation -rheumatoid arthritis,
tuberculosis

Similar tissue involvement in both primary and secondary types
 Renm liver, heart, GIT
 Hereditary

Autosomal recessive disorder involving AA amyloid (e.g., familial
Mediterranean fever)
 in individuals of Armenian, Sephardic Jewish, and Arabic origins
 a febrile disorder characterized by attacks of fever accompanied by
inflammation of serosal surfaces, including peritoneum, pleura, and
synovial membrane.

32. Localized amyloidosis
 Amyloid nodules
 AL protein
 Nodular deposits of amyloid + plasma cells in pulmo, skin,
tongue
 Alzheimer's disease
 Aβ
 Endocrine Amyloid
 certain endocrine tumors, such as medullary carcinoma of the
thyroid gland, islet tumors of the pancreas, pheochromocytomas,
and undifferentiated carcinomas of the stomach
 in the islets of Langerhans – DM type 2 diabetes
 Amyloid of Aging
 Senile systemic amyloidosis in elderly patients (usually in their
70s and 80s

With dominant involvement and related dysfunction of the heart

Senile cerebral

33. Morphology of amyloid deposition
 Histologically, the amyloid deposition is always
extracellular
 it begins between cells, often closely adjacent to
basement membranes
 WHERE?
 BLOOD VESSEL WALLS, at first
 KIDNEY
 SPLEEN
 LIVER
 HEART

34. Amyloidosis of the kidney
 Grossly
 may appear unchanged
 it may be abnormally large, pale, gray,
and firm;
 in long-standing cases, the kidney may
be reduced in size.
 Microscopically amyloid deposits are
found in:
 in the glomeruli

diffuse or nodular thickenings of the
basement membranes of the capillary
loops

total obliteration of the vascular tuft
 in the interstitial peritubular tissue

frequently associated with the
appearance of amorphous pink casts
within the tubular lumens
 in the walls of the blood vessels of all
sizes

often causing marked vascular narrowing.

35. Amyloidosis of the kidney
HE, MV

36. Amyloidosis of the spleen
 Grossly
 often causes moderate or even
marked enlargement (200-800 gm)
 firm in consistency, and cut surfaces
reveal pale gray, waxy deposits.
• Microscopically – 2 patterns of
amyloid deposits are found in:
 in the splenic folliculi

producing tapioca-like granules on
gross examination in the interstitial
peritubular tissue
 in the splenic sinuses and splenic
pulp

forming large, sheetlike deposits

"lardaceous spleen"

37. Amyloidosis of the spleen
HE, MV

38. Amyloidosis of the liver
 Grossly
 may cause massive enlargement
(as much as 9000 gm).
 the liver is extremely pale, grayish,
and waxy
 Microscopically amyloid deposits
are found in

in the space of Disse
 they encroach on the adjacent
hepatic parenchyma and sinusoids
 The trapped liver cells undergo
compression atrophy and are
eventually replaced by sheets of
amyloid

normal liver function may be
preserved even in the setting
of severe involvement

39. Amyloidosis of the heart
 Grossly
 The deposits may not be evident
on gross examination,
 or they may cause minimal to
moderate cardiac enlargement.
 There are gray-pink, dewdrop-like
subendocardial elevations,
particularly evident in the atrial
chambers.
 Microscopically amyloid
deposits are found
 throughout the myocardium

between myocardial fibers

and eventually causing their
pressure atrophy

40. Amyloidosis of the other organs
 The adrenals, thyroid, and pituitary
 amyloid deposition begins in relation to stromal and endothelial
cells and progressively encroaches on the parenchymal cells.
 In the gastrointestinal tract
 amyloid may be found at all levels, sometimes producing
tumorous masses that must be distinguished from neoplasms.
 Nodular depositions in the tongue may produce macroglossia

On the basis of the frequent involvement of the gastrointestinal
tract in systemic cases, gingival, intestinal, and rectal biopsies
serve in the diagnosis of suspected cases
 In patients receiving long-term dialysis
 deposition of β2-microglobulin amyloid occurs most commonly
in the carpal ligaments of the wrist,

resulting in compression of the median nerve (carpal tunnel
syndrome).

41. Common Types of Amyloidosis and
Associated Clinical Findings
Type of
Amyloidosis Clinical Findings
Primary and
secondary
Nephrotic syndrome, renal failure (common
cause of death)
Arrhythmia, heart failure
Macroglossia, malabsorption
Hepatosplenomegaly
Carpal tunnel syndrome
Prognosis

42. Techniques used to diagnose
amyloidosis
 Immunoelectrophoresis (to detect light
chains) in primary amyloidosis
 Tissue biopsy (e.g., adipose, rectum)
 subsequent Congo red staining is the
most important tool in the diagnosis of
amyloidosis

43. Deposition of calcium in the ECM
 Calcification - calcium salts
 Dystrophic - in dead or dying tissues
 Local causes – any type of necrosis

Atherosclerosis, LN (tbc), heart valves
 Metasatic – in hypercalcemia
 Systemic causes

Hyperparathyroidism

Renal failure

destruction of bone

vitamin D-related disorders
 affects the interstitial tissues of the
vasculature, kidneys, lungs, and gastric
mucosa.
 Macroscopy
 fine white granules or clumps
 Microscopy
 intracellular and/or extracellular
basophilic deposits

44. Deposition of urates in ECM
 Gout
 a disorder caused by the
tissue accumulation of
excessive amounts of uric
acid

result from overproduction of
uric acid, reduced excretion,
or both
 recurrent episodes of acute
arthritis, formation of large
crystalline aggregates called
tophi, chronic joint deformity
 primary (90%) and secondary
forms

45. Morphology of Gout
 Acute arthritis is characterized by a dense
neutrophilic infiltrate permeating the synovium
and synovial fluid.
 Long, slender, needle-shaped monosodium
urate crystals are frequently found in the
cytoplasm of the neutrophils as well as in small
clusters in the synovium.
 The synovium is edematous and congested, and
contains scattered mononuclear inflammatory
cells.
 Chronic tophaceous arthritis
 evolves from repetitive precipitation of urate
crystals during acute attacks.
 The synovium - hyperplastic, fibrotic, and
thickened by inflammatory cells
 Severe cases - juxta-articular bone erosions.
fibrous or bony ankylosis
 Tophi
 They can appear in the articular cartilage of joints
and in the periarticular ligaments, tendons, and
soft tissues, including the ear lobes, nasal
cartilages, and skin of the fingertips.
 Superficial tophi can lead to large ulcerations of
the overlying skin.
 Gouty nephropathy
 multiple renal complications associated with urate
deposition

medullary tophi, intratubular precipitations, or free
uric acid crystals and renal calculi

Secondary complications such as pyelonephritis can
occur, especially when there is urinary obstruction.
Gouty tophus -an aggregate of
dissolved urate crystals is
surrounded by reactive fibroblasts,
mononuclear inflammatory cells, and
giant cells