Published online Sep 26, 2020. doi: 10.12998/wjcc.v8.i18.4200
Peer-review started: July 7, 2020
First decision: July 24, 2020
Revised: August 2, 2020
Accepted: August 26, 2020
Article in press: August 26, 2020
Published online: September 26, 2020
Mucinous adenocarcinomas of the buttock are rare and have an uncertain etiology and natural course. They are usually related to chronic anal fistulas, hidradenitis suppurativa, or Crohn's disease. Here, we report a case of mucinous adenocarcinoma associated with hidradenitis and contradictory immunochemistry results.
A 62-year-old man complained of recurrent abscesses of the buttock for 3 years. He had several scars and nodules in bilateral buttocks, with purulent discharge. The skin lesions did not appear to originate from the anus. The patient was diagnosed with recurrent abscesses due to hidradenitis suppurativa at the first visit. He showed purulent and subsequent mucin discharge in the first operation and was diagnosed with mucinous adenocarcinoma. Several examinations were performed to determine disease origin and staging. There were no significant findings or evidence of anal fistulas. Hence, he underwent wide local excision and V-Y advancement flap in the second operation. The final diagnosis was mucinous adenocarcinoma without any evidence of anal fistulas. Additional immunochemistry test results were negative for cytokeratin (CK) 7 and positive for CK20 and CDX2, with a colorectal origin. A pathologist suggested that the disease originated from a chronic anal fistula. The patient has remained free of recurrence for 24 mo.
Although the patient with mucinous adenocarcinoma showed an atypical course, immunochemistry helped detect the disease origin.
Core Tip: In a case of mucinous adenocarcinoma, medical history and examinations suggested hidradenitis suppurativa as the origin. Pathologic results suggested that the disease was related to chronic anal fistulas. Results of the immunochemistry test showed that the disease had a colorectal origin. However, there was no evidence of anal fistulas, and the case did not match the diagnostic criteria previously known. Hence, the authors suggest that this case showed an atypical course related to anal fistulas.