Aggressive angiomyxoma of the perineum originating from the rectal wall.

Aggressive angiomyxoma (AA) is a rare mesenchymal tumor that preferentially involves the pelvic and perineal regions, and is characterized by frequent local recurrences. We describe here a case of large AA in a 31-year-old woman. The patient was admitted to our hospital with a mass in the perineal region, associated with severe menstrual pain. Although her past medical history was unremarkable, she had spotty pigmentation on the lips. Magnetic resonance imaging showed a large mass in the abdominal pelvis traversing the pelvic diaphragm just to the right of the anus, and the border between the tumor and the rectal wall was indistinct. Pathology examination of a frozen intraoperative specimen suggested AA, and, therefore, we completely resected the tumor, using a combined abdominoperineal approach. The tumor was attached to the right wall of the rectum and the pelvic diaphragm between the anus and the puborectalis. The patient recovered uneventfully and there has not been any evidence of local recurrence for 3 years postoperatively. We consider that abdominoperineal resection may be an appropriate treatment for a large AA infiltrating to the perirectal tissues, because the high recurrence rate of this disease has been attributed to incomplete surgical excision.