UV-B-induced bullous pemphigoid restricted to mycosis fungoides plaques

We describe a 77-year-old female patient with plaque-stage mycosis fungoides (MF) who developed bullous lesions in lesional skin only, while receiving short-wave ultraviolet radiation (UV-B) therapy. Histopathological and immunohistochemical examination resulted in a diagnosis of bullous pemphigoid (BP). Withdrawal of the UV-B treatment and application of a high-potency topical corticosteroid cream resulted in a rapid regression of the BP. As the bullous lesions were strictly confined to the MF plaques, the cutaneous infiltrate was probably involved also in the development of the BP. To our knowledge, this is the second case report of the coexistence of MF and BP and the first one in which the BP might be UV-B-induced.