Abstract

The perianal region is an unusual localization for alveolar rhabdomyosarcoma in adults. A forty-fouryear- old woman presented with a fixed solid tumoral lesion about 4 cm in diameter in the entrance of the anal canal. Following an incisional biopsy, abdominoperineal resection was performed, during which a deep subcutaneous solid, nodular mass was detected below the anal canal, gray and white in color, and 6x5.5 cm in size. It did not have any relationship with the intestinal mucosa, but showed invasion to the subcutaneous fat tissue. Microscopic examination revealed a cellular tumor divided by marked fibrous septations and consisting of large oval-round pleomorphic cells with scanty eosinophilic cytoplasm in pseudoalveolar structures. Immunohistochemical and ultrastructural examinations yielded a diagnosis of alveolar rhabdomyosarcoma. The patient died a year after surgery because of multiple metastases.