Purulent inflammation: Inflammation resulting in large amount of
pus, which consists of neutrophils, dead cells, and fluid. Infection
by pyogenic bacteria such as staphylococci is characteristic of this
kind of inflammation. Large, localised collections of pus enclosed
by surrounding tissues are called abscesses.
The pus which is the end product of this type of inflammation a
whitish-yellow, yellow or yellow-brown exudate produced by
vertebrates during inflammatory pyogenic bacterial infections. An
accumulation of pus in an enclosed tissue space is known as an
abscess, while a visible collection of pus within or beneath the
epidermis is known as a pustule or pimple. Pus is produced from
the dead and living cells which travel into the intercellular spaces
around the affected cells.
Examples for this type of inflammation:
1) Suppurative appendicitis
2) Suppurative otitis
3) Post streptococcal glomerulonephritis
5) Brain abscess
6) Purulent meningitis
7) Suppurative lymphadenitis
1) Suppurative appendicitis
Appendicitis is a condition characterized by inflammation of the
appendix. It is a medical emergency. All cases require removal
of the inflamed appendix.
Signs and symptoms of acute appendicitis can be classified
into two types, typical and atypical. The typical history includes
pain starting centrally (periumbilical) before localizing to the
right iliac fossa (the lower right side of the abdomen);
On the basis of experimental evidence, acute appendicitis
seems to be the end result of a primary obstruction of the
appendix lumen. Once this obstruction occurs the appendix
subsequently becomes filled with mucus and swells, increasing
pressures within the lumen and the walls of the appendix,
resulting in thrombosis and occlusion of the small vessels, and
stasis of lymphatic flow. Rarely, spontaneous recovery can
occur at this point. As the former progresses, the appendix
becomes ischemic and then necrotic. As bacteria begin to leak
out through the dying walls, pus forms within and around the
appendix (suppuration). The end result of this cascade is
appendiceal rupture (a 'burst appendix') causing peritonitis,
which may lead to septicemia and eventually death. Diagnosis
is based on patient history (symptoms) and physical
examination backed by an elevation of neutrophilic white blood
cells. Atypical histories often require imaging with ultrasound
and/or CT scanning. A pregnancy test is vital in all women of
child bearing age, as ectopic pregnancies and appendicitis
present with similar symptoms. The consequences of missing
an ectopic pregnancy are serious, and potentially life
threatening. Furthermore the general principles of approaching
abdominal pain in women (in so much that it is different from the
approach in men)
An exemplary case of acute appendicitis in a 10-year-old boy. The organ is
enlarged and sausage-like (botuliform). This longitudinal section shows red
inflamed mucosa with an irregular luminal surface. Diagnosed and removed
early in the course of the disease, this appendix does not show late
complications, like transmural necrosis, perforation, and abscess formation.
A. Brief Descriptions،G
1. Cause : It is associated with obstruction (fecalith, gallstone,
tumor or ball of worms).
2. Abscess formation within the wall and foci of suppurative
necrosis in the mucosa.
B. Gross Findings،G
1. Congested & swollen.
2. Dilated lumen contain pus, or a fecalith, or both.
3. Serosa coated with fibrin, fibrinopurulent exudate, or pus.
C. Micro Findings،G
1. Mucosal ulceration & infiltration by PMNs, eosinophils,
plasma cells, &lymphocytes throughout all layers & frequently
2. More advanced stage, the inflammatory process involved the
full thickness of wall,with partial necrosis or infarction of wall
1. Classified into acute, suppurative, & gangrenous stages.
site acute suppurative gangrenous
mucosa neutrophils suppurative hemorrhagic
wall neutrophils suppurative green-black
serosa congested blood purulent green-black
vessels exudates necrosis
1. Robbins Pathologic Basis of Disease, 6th ed. P.839-840.
is an ascending urinary tract infection that has reached the
pyelum (pelvis) of the kidney. If the infection is severe, the term
"urosepsis" is used interchangeably (sepsis being a systemic
inflammatory response syndrome due to infection). It requires
antibiotics as therapy, and treatment of any underlying causes
to prevent recurrence. It is a form of nephritis. It can also be
called pyelitis. Acute pyelonephritis is an exudative purulent
localized inflammation of the renal pelvis (collecting system)
and kidney. The renal parenchyma presents in the interstitium
abscesses (suppurative necrosis), consisting in purulent
exudate: neutrophils, fibrin, cell debris and central germ
colonies (hematoxylinophils). Tubules are damaged by exudate
and may contain neutrophil casts. In the early stages, glomeruli
and vessels are normal. Gross pathology often reveals
pathognomonic radiations of hemorrhage and suppuration
through the renal pelvis to the renal cortex. Chronic infections
can result in fibrosis and scarring.
Most cases of "community-acquired" pyelonephritis are due to
bowel organisms that enter the urinary tract. Common
organisms are E. coli (70-80%) and Enterococcus faecalis.
Hospital-acquired infections may be due to coliforms and
enterococci, as well as other organisms uncommon in the
community (e.g. Klebsiella spp., Pseudomonas aeruginosa).
Most cases of pyelonephritis start off as lower urinary tract
infections, mainly cystitis and prostatitis.
Untreated infection may spread and leads to gram negative
septicemia with shock.
In severe infection:
- Renal papillary necrosis caused by inflammatory thrombosis of
vasa recta supplying the papillae.
- Infection spreads to perinepheric fat.
- Pyonephrosis (Distension of pelvicalyceal system with
pus) maybe present.
Acute pyelonephritis is an exudative purulent localized
inflammation of kidney and renal pelvis. The renal parenchyma
presents in the interstitium abscesses (suppurative necrosis),
consisting in purulent exudate (pus): neutrophils, fibrin, cell debris
and central germ colonies (hematoxylinophils). Tubules are
damaged by exudate and may contain neutrophil casts. In the
early stages, glomeruli and vessels are normal. (Hematoxylin-
eosine, ob. x10)
Infectious disease that involves the inflammation of the
meninges, which often extends to the brain and ventricles,