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I Lumen:
Debris covering
the mucosa should be examined for microorganisms.
(Fig 1).
Debris
usually consists of sloughed epithelial cells, neutrophils and
sometime eosinophils.
Pus in the lumen
is suggestive of pathology nearby.
Further levels
are indicated.
Neutrophils
arranged in a linear pattern in the lumen (Fig 2)
is
suggestive of
pseudomembranous colitis
and deeper levels should be examined.
Amoebae
(Fig 3)
are often present in the debris.
These should
not be mistaken for foamy macrophages.
The organisms
are PAS positive and contain red blood cells.
II. Surface epithelium:
Normal mucosal
surface of the colon and rectum is almost flat. In chronic idiopathic
inflammatory bowel disease surface irregularity is of variable
severity.
In some cases
the surface shows villous or pseudovillous pattern. This is a marker
of inflammatory bowel disease.
[
Note:
Erosion is loss
of surface epithelium with underlying inflammation. Ulceration is
characterized by damage to a greater thickness with underlying
granulation tissue formation ].
Cuboidal
change or flattening (loss of columnar shape of the epithelial cells)
indicates mucosal damage and cell restitution.
Biopsy trauma
may cause artifactual stripping of surface epithelium.
(Fig 4). There
are viable cells in the lumen, debris, red blood cells on the surface
and absence of inflammatory infiltrate in the lamina propria. Surface
degeneration without inflammation could be due to poor tissue
fixation. Surface degeneration and superficial inflammation without
other features could be due to irritative enema or due to some form of
iatrogenic trauma.
Surface degeneration with acute inflammation is a non-specific feature
of any of the causes of coloproctitis and is accompanied by other
changes in the lamina propria. (eg. Acute infective colitis).
Tufting of
degenerated surface epithelium
(Fig 5)
with acute inflammation, commonly noted in infective colitis and
pseudomembranous
colitis
. Further
levels are indicated.
Microorganisms
may be present. Spirochaetosis is characterized by fuzzy & thickened
surface.
(Fig 6)
.
Organisms are better demonstrated by Warthin - Starry stain.
Cryptosporidia
are
identified as tiny haematoxyphilic dots. This may be confused
with stain deposits or nuclear debris.
Intraepithelial
lymphocytes are increased in lymphocytic colitis (20 per100
epithelial cells). IEL are also increased in
coeliac disease. (Normal IEL count - 5 IEL per 100 epithelial cells).
Abstract
Increased
number of apoptotic bodies
in the surface epithelium is abnormal. (eg. Use of non-steroidal
anti-inflammatory drugs ,,
graft versus host disease, HIV infection).
III. Subepithelial zone: (Path Case38)
Normal thickness of the subepithelilal collagen is usually not more
than 3 micrometer.
According to some authors the normal range is 3 to 6.9 micrometer. In
collagenous colitis
it is more than 10 micrometer. The thickening may be patchy and
confined to the proximal part of the colon.
Note:
Diagnosis
of collagenous colitis should not be made based only on thickened
subepithelial collagen plate at any one point of the biopsy.
D/D.
Due to tangential cutting there is apparent thickening of basement
membrane. Nuclei in the surface epithelium may shift upwards resulting
in eosinophilic subnuclear zone mimicking
collagenous colitis.
Thickening of
collagen plate has also been observed in some cases of diverticular
disease, colonic carcinoma , Crohn's disease and pseudomembranous
colitis
.
Visit:
Features of normal large bowel mucosa :
click
Interpretation of Large Intestinal Biopsies :
click
Assessment of the
Intestinal abnormalities
:crypt density,
architecture and epithelium : click
Assessment of abnormalities :changes in the lamina propria,muscularis mucosae and submucosa ):
click
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