Mucinous adenocarcinoma associated with chronic anal fistula reconstructed by gracilis myocutaneous flaps

Mucinous adenocarcinoma associated with chronic anal fistula is extremely rare, and such tumors have often reached an advanced stage at the time of presentation. Here we report a case of mucinous adenocarcinoma associated with chronic anal fistula that involved repair with gracilis myocutaneous flaps and review other reported cases. A 67-year-old man with an approximate 30-year history of an anal fistula was referred to our hospital due to enlargement of the perianal induration accompanied by mucinous secretion and pain. Physical examination of the perianal region revealed an ulcerated and discharging lesion on the buttocks. Histologic examination of a biopsy specimen of the ulcerated lesion revealed mucinous adenocarcinoma. An abdominoperineal resection was performed with resection of the ischiorectal fossa, coccyx, part of the gluteus maximus, and the obturator internus. The extensive defect was repaired with bilateral gracilis myocutaneous flaps. The patient did not experience a decrease in the strength of hip adduction and survived for 58 months without recurrence until he died of pneumonia. The repair using myocutaneous flaps was considered to contribute to a physically active life without recurrence.