Perianal basosquamous carcinoma treated with radiation therapy, a case report

Background: Perianal basal cell carcinoma (BCC) is very rare and estimated to account for 0.08% of all BCC and 0.02% of all anorectal neoplasms. Perianal lesions are more likely to be squamous cell carcinoma (SCC) as BCC usually develops on areas of skin exposed to ultraviolet (UV) light such as the face and arms. Proper diagnosis with the assistance of immunohistochemistry (IHC) stains to distinguish the two entities can help inform the suitable course of treatment. Case Description: Our case is an 82-year-old male with a history of cutaneous BCC on the arms and trunk presenting with a symptomatic perianal lesion. Initial biopsy demonstrated BCC with subsequent IHC studies differentiating from basaloid SCC. Standard treatment includes wide local excision (WLE) but given his poor performance status, radiation only was recommended. He was successfully treated and tolerated 30 Gy in 5 daily fractions. Conclusions: Radiation only is a unique and feasible non-surgical treatment for basosquamous carcinoma of the anus.