[Diagnosis and treatment for carcinoma associated with anal fistula].

In this article, we focus on the diagnosis and treatment of carcinoma associated with anal fistula. Carcinoma associated with anal fistula is relatively rare, representing 6.9% of all anal carcinoma in Japan. It arises from long-standing anal fistula with more than 10 years duration. Clinical suspicion is crucial in diagnosis, however, early detection is challenging. A biopsy under anesthesia is often needed for histological confirmation of the tumor. Magnetic resonance imaging can facilitate the diagnosis and is essential to determine the range of the surgical resection. Abdominoperineal resection is usually performed as the surgical treatment of choice. Combined chemoradiation therapy may improve the outcome of locally advanced tumor.