[Mucinous adenocarcinoma on chronic perianal fistula treated by neoadjuvant chemoradiotherapy and laparoscopy-assisted abdominoperineal amputation].

We present a male patient with a perianal fistula of 30 years' duration that had been treated on several occasions. The patient presented with mucoid anal adenocarcinoma. He was treated with preoperative neoadjuvant chemotherapy (5-FU and leucovorin) and external radiation therapy plus laparoscopy-assisted abdominoperineal amputation. Mucoid adenocarcinoma on chronic perianal fistula is an infrequent process. Late diagnosis is associated with a poor prognosis.