Squamous cell carcinoma arising in chronic perianal pyoderma a case report and review of Japanese literature.

We report a rare case of squamous cell carcinoma developing from fistules of chronic perianal pyoderma in a 49-year-old Japanese man. He first noticed an abscess and nodule on his buttocks and perianal area 21 year previously (at the age of 28); the fistules formed later. These fistules were surgically removed, and an artificial anus was constructed 14 years ago (at the age of 35) in our hospital, when a histopathological examination revealed no malignant changes. However, he was recently admitted to our hospital with arterial bleeding from the ulcer of the buttock. On admission, the histological diagnosis of the ulcer was well differentiated squamous cell carcinoma. Wide local excision of the ulcer and scar tissue, including the sacrum, was performed. The defect was covered with a left latissimus dorsi flap and skin graft. He received radiation therapy after the operation. However, he died of cachexia and pneumonia. This case indicated that the CPP would better have been treated with wide excision before the development of SCC. Therefore, we recommend careful follow-up of patients affected by CPP and repeated biopsies of the lesion, particularly when the condition is severe, longstanding, and extensive. We discussed the term "CPP" and reviewed 22 cases of SCC arising in CPP reported in the Japanese literature.