Cutaneous type of adult T cell leukemia/lymphoma: a new entity among cutaneous lymphomas.

Adult T cell leukemia/lymphoma (ATL) is a malignancy of CD4+ T cells that is endemic in certain areas in Japan. Two types of cutaneous ATL thought to originate from skin include cutaneous tumor and erythematopapule types. Patients with cutaneous ATL show neither leukemic involvement nor invasion of tumor cells into the lymph nodes for at least six months. The differential diagnosis between cutaneous ATL and mycosis fungoides is often difficult. The presence of monoclonal integration of human T lymphotropic virus-I proviral DNA in skin samples is of definitive diagnostic value in cutaneous ATL.