Inflammatory polyps are
the most common type of polyp in Inflammatory bowel disease.
polyps usually occur in patients with moderate to severe colitis but
persist in patients with quiescent disease.
Inflammatory polyps also occur in association with Crohn's disease and
other inflammatory disorders of the GI tract such as ischemic colitis or
These polyps may occur in infective conditions such
as amoebiasis, schistosomiasis and bacillary dysentery.
A special form of inflammatory polyp develops in the colon at the site
of ureteric implantation where probably due to chemical irritation there
is localized expansion of lamina propria and cystic dilatation of
In order to determine the underlying disease it is necessary to examine
non-polypoid mucosa, which should be biopsied at the same time.
developed as a regenerative response to localized or diffuse
inflammation and ulceration of the mucosa followed by regeneration of
the intervening non-ulcerated epithelium.
Eventually the regenerated
mucosa become completely re-epithelized and persists above the level of
the surrounding mucosa as inflammatory polyps.
Sometimes inflammatory polyps represent spared mucosa surrounding areas
of deep ulceration.
Some polyps decrease in size, most remain stable a few may continue to
grow if they undergo torsion or prolapse.
sessile, pedunculated or may consist of long finger-like projection
referred to as 'filliform'.
These polyps may be single or numerous in
number and the size range between 0.5 - 1.0 cm.
'Giant Inflammatory polyps' may cause bleeding, obstruction, prolapse or
The inflammatory polyps are characterized
Inflamed lamina propria ; distorted colonic epithelium - tortuous,
branched, elongated and cystic crypts; surface erosion ; congestion ;
haemorrhage ; crypt abscesses.
In some cases pseudosarcomatous changes are noted characterized by
Enlarged spindle or epithelioid shaped multinucleated bizarre stromal
cells, present at the surface of ulcerated polyp.
Differential diagnosis -
(1) These lesions lack atypical mitosis
(2) Located within granulation
tissue and below areas of ulcerataion
(3) Positive for
endothelial and myofibroblastic markers.
or carcinoma may develop in inflammatory polyps. However, the risk of
developing dysplasia is very low and these polyps are not considered
Pathology of Inflammatory Cap Polyps:
Inflammatory cap polyps are defined as an inflammatory polyp either with
or without prolapse-related changes that contain an overlying 'cap' of
necroinflammatory debris and granulation tissue.
These inflammatory polyps may develop in inflammatory bowel disease
either primarily or secondarily as a result of peristalsis or trauma
induced mucosal prolapse.
This may lead to traction and twisting of polyps
causing localized ischemic damage, regeneration and repair of the lamina propria
and epithelium and the development of an inflammatory polyp.
may be associated diverticular disease.
These polyps are usually isolated lesions, but can be numerous in number
- ( 'cap polyposis').
Cap polyps are usually located in the sigmoid colon and rectum of adults.
These are sessile haemorrhagic polyps, present on the crest of mucosal
folds and are less than 1 cm in diameter.
The patients present with rectal bleeding and mucous diarrhea.
In some cases these are also seen in the small intestine complicating
Pathology of Polypoid Mucosal Prolapse:
Few important features:
solitary ulcer (mucosal
prolapse) can be polypoid.
- May be present in diverticular
on the apices of mucosal folds.
- Subsequent to
previous surgery (Example: Stomas or pelvic ileal reservoir)
- Inflammatory Cloacogenic polyps -
At the anorectal junction. There is florid villiform epithelial
hyperplasia. Associated with haemorrhoids and pelvic descent syndromes.
Myoglandular polyps - Usually in sigmoid colon.