Low-Dose X-Ray Depilatory Treatment Induces Trichoblastic Tumors of the Scalp

Background: Depilatory radiotherapy for ringworm was largely used before antifungals were available. Patients who underwent this treatment are at high risk of developing scalp tumors or other cancers. The aim of this study was to characterize scalp tumors occurring after X-ray therapy for ringworm. Methods: We included cases of postradiotherapy scalp tumors recorded at the Dermatology Department of the Charles Nicolle Hospital, Tunis between 1988 and 2001. We recorded clinical descriptions and all cases were resubmitted to microscopic analysis. Results: Sixty-one tumors occurred in 33 men and 12 women with a mean age of 49.8 years. Radiodermatitis was present in 21% of patients. Tumors were basal cell carcinomas in 47 cases, trichoblastomas in 10 cases and trichoblastic carcinomas in 4 cases. Twelve patients had 2–5 tumors, with combinations of tumor types in 3 of them. Mean delay of onset of tumors after radiotherapy was 39.4 years in basal cell carcinoma cases, 38.3 years in trichoblastoma cases and 35.6 years in trichoblastic carcinoma cases. Conclusions: This series shows that although basal cell carcinoma is the most frequent tumor in this situation, trichoblastomas are common. We describe, for the first time, radio-induced trichoblastic carcinomas. Trichoblastic tumors have not yet been described in this context because this concept is relatively recent.