May 19th, 2021

This lesion was found in the rectum of a patient undergoing colonoscopy because of constipation
WHAT IS THE LIKELY DIAGNOSIS?

■ Polyp from mucosal prolapse

Clever!

■ Serrated polyp

Crypts look a little serrated but the rest doesn't

■ Adenomatous polyp

Polyp doesn't look 'neoplastic'

■ Malignant polyp

Now, this doesn't look malignant!

explanation

Well perhaps the crypts look a little like serrated crypt openings but somehow the rest of the polyp doesn't look like a typical serrated lesion.  Where is the covering mucus?!   Furthermore, the polyp definitely doesn't look adenomatous or malignant! 

Actually this has arisen as part of the 'Mucosal prolapse syndrome' which is the umbrella term for entities such as; solitary rectal ulcer syndrome and inflammatory cloacogenic polyps. 

Patients are often constipated or have difficulty with defaecation with straining on the toilet or undergo the sigmoidoscopy because of tenesmus, altered bowel habits or incontinence. Surprisingly, some patients don't have any straining-related complaints! 

Most pathologists would recognise the typical mild fibrosis, thickening of the muscularis mucosae and crypt irregularity (dilated, diamond shape crypts). The surface epithelium show regenerative changes.