- Human pathology

Home > E. Pathology by systems > Digestive system > Colon and rectum > inflammatory cap polyp

inflammatory cap polyp

Tuesday 20 March 2012

Inflammatory cap polyps develop in the setting of anorectal mucosal prolapse, affecting patients of all ages.

The patients present with diarrhea, mucoid stools, gastrointestinal bleeding, and/or tenesmus.

The lesions usually arise in the rectosigmoid and are often multiple, measuring in size from a few millimeters to 2 cm.

The lesions lie on the crests of the mucosal folds separated by normal or edematous mucosa.

They likely arise secondary to transitory mild ischemia that occurs when the mucosa and submucosa prolapse.

These non-neoplastic lesions consist of elongated, tortuous hyperplastic crypts.

These are frequently dilated and inflamed.

There is acute and chronic inflammation in the lamina propria and a characteristic cap of inflamed granulation tissue and fibrin covers the mouths of adjacent crypts.

The polyps may mimic hyperplastic polyps or adenomas, except for the distinctive covering cap.

The stroma frequently contains hyperplastic frayed smooth muscle
bundles extending up from the muscularis mucosae, a feature commonly seen in anorectal mucosal prolapse.