Phenotype / cell stem origin These are peripheral T-cell tumours, usually expressing CD4 along with other T-cell markers. The CD30 molecule is expressed in a histologically distinct subset (vide infra). Classification: The WHO identifies some well-defined clinicopathological entities with distinct clinical behaviour. Indolent forms include mycosis fungoides, primary cutaneous CD30 (Ki1) positive anaplastic large cell lymphomas and its benign variant lymphomatous papulosis; aggressive forms include Sezary's syndrome and peripheral CD30-negative T-cell lymphoma. Epidemiology Primary cutaneous non Hodgkin's lymphomas (NHL) has an approximate 0,4/100.000 incidence in the U.S. The majority of patients are between 40 and 60 years old. Clinics Details on clinics, pathology, cytogenetics and molecular cytogenetics can be found in disease-specific cards (i.e. mycosis fungoides / Sezary's syndrome, primary cutaneous CD30 positive anaplastic large cell lymphoma).