Abstract
A 77-year-old man was seen at the department becausse of a tumor on the right side of the anus.There was a past history of undergoing an operation for fistula-in-ano at the age of 69, which, however, had relapsed with perianal abscess formation, and had been left untreated. The tumor, measuring 12 cm in diameter, had an cauliflower-like appearance with mucin secretion causing severe stenosis in the proctum. It bleed easily with contact. MRI and angiography vizualized the tumor as a giant hypovascular mass in the right ishiorectal fassa with an extraluminal growth. Although colonoscopy showed severe stenosis in the proctum, no abnormality was detected in the mucosa. Since the biopsy form the tumor led to the diagnosis of mucinous carcinoma, abdomino-perineal resection of the rectum with D2 lymphadenectomy and extensive perianal skin resection was carried out. The defect in the pelvic cavity needed a repair and plasty using the bilarteral gracilis muscles with a skin flap. Histopathological examination of the resected specimen revealed a mucinous carcinoma with multiple mucin production arround the fistula. The tumor was fistula-cancer showing an extraluminal growth.
