In adults, rectal leiomyosarcoma is uncommon, and anal leiomyosarcoma is even more rare. We report one patient with anal leiomyosarcoma and one patient with a biphasic clinical history, with three occurrences of perineal leiomyosarcomas after surgically resected rectal leiomyoma. We discuss the characteristics of these rare entities based upon a review of the literature.