Perianal mucinous adenocarcinoma presenting as recurrent perianal sepsis

Abstract

Introduction Mucinous adenocarcinoma can rarely present as recurrent perianal sepsis and may be defined by specific neoplastic involvement of perianal tissue in the absence of rectal mucosal carcinoma. It accounts for less than 5% of tumours in this region. These tumors are usually well-differentiated and present late because of their insidious slow growing nature. These lesions are often mistaken for a benign condition like perianal fistula and abscess. Neoadjuvant radiotherapy and radical resection of mucinous adenocarcinoma with abdominoperineal resection is the treatment of choice. We present such a case along with a review of literature concerning its etiopathology. Case description A 68-year-old man presented with 6 episodes of perianal sepsis over the course of a year. He had no history of previous perianal sepsis, diabetes or Crohns disease. His past medical history included ischaemic heart disease. He was a previous smoker, with a 20-pack year smoking history. The patient underwent examination under anaesthetic and incision and drainages of perianal abscesses on multiple occasions. A pelvic MRI scan demonstrated the fistulous tract and a chronic abscess. Initial biopsies taken from the rectal mucosa and fistula tract were unremarkable. However, biopsies taken during his sixth examination under anaesthetic revealed mucinous adenocarcinoma. Results Patient had neoadjuvant radiotherapy followed by curative abdominoperineal resection (APR) with satisfactory outcome. Take home message Expeditious identification and management is associated with favourable outcomes. In patients presenting with ongoing perianal sepsis, one should have high index of suspicion and the diagnosis of mucinous adenocarcinoma should be considered.