Anal margin neoplasm

What it means

A tumor of the anal margin.

The anal canal is defined as the caudal part of the large intestine extending from the anorectal ring to the anal verge and is about 3 to 5 cm in length. Outside of the anal verge lies the anal margin, also referred to as the perianal skin, which commonly encompasses a radius of 5 cm. The anal verge can be identified visually as the part of the anal canal remaining closed when the buttocks are gently retracted. The upper anal canal is lined by columnar tissue that transitions into squamous epithelium at the dentate line. The dentate line, identified by the termination of the anal columns, lies 1 to 2 cm above the anal verge.

Part of the broader category