title: Infiltrating adenocarcinoma arising in a villous adenoma of the anal canal.
abstract: Primary neoplasms arising in the anal canal are relatively unusual. In particular, adenomas and adenocarcinomas are distinctly rare entities in this region. We describe an infiltrating, well-differentiated adenocarcinoma arising in a villous adenoma from the distal anal canal, in an otherwise healthy patient at low risk for gastrointestinal malignancy. This is the case of an octogenarian man with a several year history of hemorrhoids and intermittent rectal bleeding, more recently complaining of continuous hematochezia. Examination revealed a blood-covered pedunculated mass with a long stalk protruding from the anus. The lesion was amputated at the bedside. Microscopic evaluation revealed an infiltrating well-differentiated adenocarcinoma, arising from a villous adenoma. This was further evaluated under anesthesia and complete excision of distal anal tissue was performed. Our report is the first describing the possible malignant degeneration of a villous adenoma in the anal canal.
authors.affiliation: Department of Surgical Oncology, University Medical Center, Tucson, AZ 85724, United States.
authors.forename: Marni
authors.initials: M
authors.lastname: Colvin
authors.forename: Aris
authors.initials: A
authors.lastname: Delis
authors.forename: Erika
authors.initials: E
authors.lastname: Bracamonte
authors.forename: Hugo
authors.initials: H
authors.lastname: Villar
authors.forename: Luis R
authors.initials: LR
authors.lastname: Leon
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D018253:Adenoma, Villous / Q000473:pathology* / Q000601:surgery; D000369:Aged, 80 and over; D001003:Anal Canal / Q000473:pathology* / Q000601:surgery; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D018450:Disease Progression; D006801:Humans; D008297:Male; D016896:Treatment Outcome