Abstract
Epidermoid cyst (atheroma) is a commonly observed benign tumor of the skin that rarely results in malignant transformation. We encountered a patient with squamous cell carcinoma probalby developed from a long-standing epidermoid cyst. A skin tumor on the right buttock of a 78-year-old male had grown for 60 years and formed an intractable fistula two months before his first visit to our hospital. When hospitalized two weeks after the visit, the patient was found to have a granulation tissue-like tumor bulging out of the fistula, and swelling of the inguinal lymph nodes. Histopathological examination following tumor excision and lymph node dissection indicated squamous cell carcinoma probably developed from an epidermoid cyst and lymph node metastasis. Since atheroma may, though rarely, lead to malignant transformation, treatment by resection is recommended for the disease. Over 25 similar cases have been reported in Japan.
