Alpha-Methylacyl-Coenzyme A Racemase-Expressing Urachal Adenocarcinoma of the Abdominal Wall

Urachal adenocarcinomas are very rare and about one third of these neoplasms arise in urachal remnants. To demonstrate the origin of the urachal adenocarcinoma is not easy, but it is very important for managing patient care. We report on a 35-year-old man who complained of a palpable mass in the periumbilical area. The mass was incidentally identified 10 days earlier. Computed tomography revealed a well-defined enhancing mass with internal calcification and septation abutting on the dome of the urinary bladder. The clinical diagnosis was urachal cancer, which seemed to invade the urinary bladder. Thus, we performed mass excision and partial resection of the bladder. Histopathologically, the mass was diagnosed as mucinous cystadenocarcinoma originating from urachal remnants that showed an unusual expression of alpha-methylacyl-coenzyme A racemase (AMACR). To our knowledge, this report is the first case of AMACR-expressing urachal adenocarcinoma arising in the abdominal wall.