CT and MR Imaging Findings of Perianal Dermatofibrosarcoma Protuberans Mimicking Mucinous Adenocarcinoma Arising from Fistula in Ano: A Case Report

Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue tumor with a low malignant potential and a high local recurrence rate after surgical excision (1). DFSP can be found anywhere on the body, but is often found on the chest and shoulders (1). DFSP arises in the dermis and invades deeper tissues such as fascia, muscle and bone (1, 2). Due to its tendency for local invasion and asymmetric spread, DFSP in the perianal area can extend to the anal sphincter and show similar imaging findings to those of a malignant tumor arising from the anorectal fistula. However, DFSP in the perianal area is extremely rare, and only one case has been reported in the English medical literature (3). To the best of our knowledge, there is no report regarding the detailed imaging findings of DFSP radiologically mimicking mucinous adenocarcinoma arising from the anorectal fistula. We present an extremely rare case of perianal DFSP mimicking mucinous adenocarcinoma arising from fistula in ano, and focus on the CT and MR imaging findings. This report was approved by the ethics committee at our institution, and the requirement for informed consent was waived.