Disseminated superficial porokeratosis developing after electron-beam total skin irradiation for mycosis fungoides.

A 74-year-old man with stage IB cutaneous T-cell lymphoma was treated with electron-beam total skin irradiation in 1988. Seven years later, multiple disseminated lesions of porokeratosis developed on the chest, extremities and abdomen. There was no family history of porokeratosis, nor history of treatment with PUVA or of excessive sun exposure. Development of disseminated porokeratosis on nonexposed sites suggests a direct role for the previous ionizing radiation. Electron-beam total skin irradiation therapy should therefore be added to the list of possible causative factors in the development of disseminated porokeratosis.