Cutaneous true histiocytic malignancy: true histiocytic lymphoma.

True histiocytic malignancies (THM) are controversial disorders that are being re-evaluated with modern cellular and molecular biology techniques. True histiocytic lymphoma (THL) is a low-incidence, poor-prognosis THM. It mainly affects the skin, gastrointestinal tract, and bone tissues. Occasionally, skin lesions are the presenting clinical features. A patient with initially cutaneous THL is described. This and other reported cases confirm that THM are a nosologic entity by themselves.