Basosquamous Cell Carcinoma of the Anus

Abstract

Cancer of the anus is a rare neoplasm in the general population and accounts for only about 1.2–2 % of gastrointestinal cancers [1–3]. Anal carcinoma usually appears in the fifth and sixth decades of life and shows a female predominance [1–3]. Regarding anatomy, anal carcinomas are divided into those occurring within the anal canal and those occurring at the anal verge [1]. The most common malignant anal tumor is squamous cell carcinoma and its variants whereas other more rare lesions include adenocarcinoma, small cell carcinoma, undifferentiated carcinoma, melanoma, lymphoma sarcoma, and perianal basal cell carcinoma [1–3]. Basal cell carcinoma is a very rare anal tumor of the anal margin representing only 0.2 % of the anorectal tumors [1, 4] and with only a few more than a hundred cases having been reported [5]. Clinically, the cancer presents usually as a slowly growing sharply marginated area with raised edges and central ulceration which can extend into the anal canal to the squamous zone [3–5]. We present a very rare case of basosquamous carcinoma of the anus and emphasize this rare aggressive variant of basal cell carcinoma and its differential diagnosis from basaloid carcinoma an aggressive variant of squamous cell carcinoma.