Abstract
A 42-year-old woman was admitted for abdominal distension and constipation. She underwent subtotal colectomy, distal gastrectomy and management with home parenteral nutrition for intractable anal fistula due to Crohn's disease for over 10 years. CT and MRI showed rectal stenosis. She was diagnosed as anal canal cancer by incisional biopsy for perianal inflammatory polyp. Posterior pelvic exenteration followed by latissimus dorsi musculocutaneous free flap reconstruction were performed. In the specimen, there was a type-5 tumor at around the primary opening of the anal fistula on the anterior wall of the rectum, the maximum diameter of which was 35 mm. Pathologically it was well differentiated adenocarcinoma, and mucin-producing tumor cells were involved in the posterior wall of the vagina. However, there was no continuity of cancer lesion to the anal fistula, so the final diagnosis was anal canal cancer with Crohn's disease.
