Periungual porocarcinoma.

We describe a patient who developed a porocarcinoma in the nail bed. His profession had exposed him to X-rays for many years, resulting in chronic radiodermatitis of several digits on both hands. He displayed an ulcer in the lateral nail fold of the right third digit which extended into the nail bed. The histology of the lesion was consistent with malignant eccrine poroma. Porocarcinoma has not been previously published in this location and this tumor must be considered in differential diagnosis of subungual malignant tumors.