[Leiomyosarcoma of the anal canal]

Leiomyosarcoma originating in the anal canal internal sphincter is an extremely rare malignant tumor of often late diagnosis, since usually asymptomatic, and with malignancy criteria that are sometimes difficult to define. These tumors affect men and women with equal frequency, usually in the 6 th decade. Two cases are reported in patients aged 67 and 65 respectively in whom the tumor was revealed by a painful perianal mass shown on rectoscopy to be due to a submucous tumor projecting into anal canal, Prognosis and treatment of these tumors is discussed, diagnosis being confirmed only after excision biopsy. Tumoral extension was both local and regional by continuity but blood dissemination had occurred with metastases more frequently in liver (1 case) but also in lungs. Glandular extension was exceptional. Limited local exeresis of small tumors appears justified if sufficiently wide, since malignancy of leiomyosarcoma appears to remain circumscribed over long periods. However, this limited procedure runs the risk of local recurrence with the need for abdominoperineal amputation (the case in the 2 patients reported), although long-term results appear to be similar whether excision is or is not extensive, the abdominoperineal amputation failing to avoid the unfavorable course. Complementary radiotherapy or chemotherapy is ineffective, and prognosis is related more to the degree of tumoral differentiation than to the operative treatment itself.