Prolapse-induced inflammatory polyps of the colorectum and anal transitional zone.

A clinicopathological study of polypoid lesions of the lower gastrointestinal tract from 12 patients was undertaken. Clinically, the majority had signs and symptoms of rectal prolapse despite having a variety of other primary diagnoses (e.g. carcinoma of the bowel or diverticular disease). Three patients were asymptomatic. The polyps were more common in females and were usually solitary. Histologically, fibrin 'caps', fibromuscular hypertrophy and obliteration of the lamina propria, goblet cell hypertrophy and serrated tubules were consistently noted. The fibromuscular tissue often extended into the lamina propria in a radial fashion. This study shows that mucosal prolapse underpins a variety of lesions that are part of a histological spectrum of changes. Inflammatory cloacogenic polyps, inflammatory 'cap' polyps, polypoid prolapsing mucosal folds of diverticular disease and inflammatory myoglandular polyps are all due to mucosal prolapse.