title: Primary cutaneous CD20-positive T-cell lymphoma.
abstract: CD20 is a transmembrane protein that is expressed by B cells during their development and is, therefore, commonly used to label cells of B lineage in lymphoid infiltrates. CD20-positive T-cell lymphoma is infrequent but well recognized. Cases reported in the literature show a variety of clinical and histoimmunochemical profiles. Primary cutaneous CD20-positive T-cell lymphoma is vanishingly rare; only eight cases have been previously reported. We present two new cases of this entity and describe their clinical, histological and immunohistochemical features. CD20 is a highly specific B-cell marker. However, it has been reported in a subset of normal T-cells in peripheral blood and bone marrow of healthy individuals. This subset of T-cells also expresses more often CD8 and g/d than the CD20-negative T-cells. Two main theories have been postulated to explain the expression of CD20 by neoplastic T-cells. The first possibility is that these lymphomas develop from the CD20-positive subset of normal T-cells. The second theory regards CD20 as an activation marker. Prognostic implications and therapeutic options of T-cell lymphomas with positivity for CD20 remain to be elucidated.
authors.affiliation: Department of Dermatopathology, St John's Institute of Dermatology, St Thomas Hospital, London, UK. blancamartin@hotmail.com
authors.forename: Blanca
authors.initials: B
authors.lastname: Martin
authors.forename: Catherine
authors.initials: C
authors.lastname: Stefanato
authors.forename: Sean
authors.initials: S
authors.lastname: Whittaker
authors.forename: Alistair
authors.initials: A
authors.lastname: Robson
mesh_terms: D000369:Aged, 80 and over; D018951:Antigens, CD20 / Q000378:metabolism*; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism; D016827:CD8 Antigens / Q000378:metabolism; D006801:Humans; D016410:Lymphoma, T-Cell, Cutaneous / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology
chemical_list: D018951:Antigens, CD20; D014408:Biomarkers, Tumor; D016827:CD8 Antigens