Malignant skin tumors are known to develop in areas of chronic radiodermatitis. We experienced a patient with multiple basal cell carcinomas that developed about 50 years after irradiation. The patient was a 77-year-old man who underwent radiotherapy in his twenties for caries in the left shoulder joint. The dose given was unknown. Black skin tumor appeared initially about 10 years before the first consultation. The skin around the tumor began to erode about six months before presentation. Biopsy of the tumor was done at another institution and revealed basal cell carcinoma(BCC), so the patient was referred to our department. In addition to the BCC measuring 35×20mm in the left shoulder, BCC measuring 17×20mm and 15×15mm were found on the chest and the left axilla, respectively. The lesions were excised with a margin of 5mm from the radiodermatitis, and the resultant skin defects were covered with latissimus dorsi flaps. All three tumors were basal cell carcinomas. The patient died of an unrelated disease six years after surgery and there was no recurrence of his tumors.
