A rather bland looking polyp

This lesion in the low rectum has been referred for endoscopic resection
WHAT IS YOUR DIAGNOSIS?

a) Mucosal prolapse syndrome

Well done!

b) Sessile Serrated lesion

Looks just like it but it isn't!

c) Traditional Serrated Adenoma

That's a No!

d) Adenomatous polyp

Patient complained of constipation...

e) Malignant polyp

But it's not 'chunky', red and it has crypts ?!?

explanation

There is no distinct edge to the 'polyp' and the crypts look normal, although a little splayed out and larger than normal, reminiscent of a serrated polyp.  In real life, I had the advantage of knowing that the patient had been sent for colonoscopy because of constipation. I low-risk indication of course.

There is no distinct edge to the 'polyp' and the crypts look normal, just a little splayed out and larger than normal. This 'polyp' is actually part of the "Mucosal prolapse syndrome", first described in 1983 by Du Boulay et al [J Clin Pathol. 1983;36:1264–8].

Obviously, this syndrome includes solitary rectal ulcers, inflammatory cloacogenic polyps but also rectal 'prolapse polyps' such as this. In addition, the 'Mucosal Prolapse Syndrome' includes those prolapsing mucosal folds in the sigmoid and perhaps most surprisingly - GAVE !

In a case like the above, a couple of superficial biopsies will usually reveal the true nature of the lesion as it's easy for pathologists to spot the fibromuscular hyperplasia with overlying epithelial crypt distortion rather than dysplasia.