Lichen planus induced by radiotherapy.

A 44-year-old woman presented at our department in 2003 with multiple pruritic papules spread over her trunk and extremities, and was diagnosed with LP. No mucosal lesions were observed. The diagnosis was histologically confirmed. Viral infection, contact with triggering substances, and use of medications were all ruled out. Treatment with sulfasalazine was begun and 5 months later, the lesions had disappeared. After a lesion-free period of 2 months, the patient was diagnosed with infiltrating ductal carcinoma in the left breast. She underwent a tumorectomy and was treated with chemotherapy and external radiotherapy of up to 60 Gy in the left breast, completing treatment after 2 months. Five months after terminating radiotherapy, the patient returned to our department, reporting a 4-month evolution of shiny violaceous papules clustered in the inframammary crease. The cutaneous lesions coincided exactly with the irradiated area (Fig. 1). A biopsy was performed and histopathological findings were consistent with LP. After 1 month of treatment with clobetasol propionate 0.05%, the lesions disappeared.