title: Immunohistochemical analysis of mycosis fungoides on paraffin-embedded tissue sections.
abstract: Mycosis fungoides (MF) is typically characterized by dermal and epidermal infiltration of T lymphocytes with a helper/inducer phenotype. Immunophenotypic analysis of such cases was traditionally performed by flow cytometry or immunohistochemistry on cryostat sections. With the advent of new monoclonal antibodies developed against T-cell antigens, including CD3, CD4, CD5, and CD8, it is now possible to immunophenotype T-cell subpopulations in paraffin-embedded tissues. To investigate the potential use of these antibodies for the evaluation of cutaneous lesions, 35 specimens (34 skin and 1 lymph node) from 29 patients with MF were retrospectively reviewed and immunophenotyped in paraffin sections with antibodies to CD3 (T-cell CD3), CD4 (NCL-CD4-1F6), CD5 (NCL-CD5-4C7), CD8 (CD8/144B), and CD20 (L26). Epidermal and dermal distribution of T and B cells were analyzed, and we assessed the ratios of CD4+ to CD8+ T cells. All of our 35 cases demonstrated a predominant CD3+ T-cell population. In 32 cases, the neoplastic cells expressed CD3, CD4, and CD5 consistent with a T-helper/inducer phenotype. In three cutaneous cases, the neoplastic CD4+ T cells showed minimal or absent expression of CD5, indicating an aberrant phenotype. In the majority of cases, minimal CD8+ T cells were present in the background, but in four cases, the CD4:CD8 ratios were 2:1 or less. Thirty-two cutaneous cases demonstrated epidermotropism exclusively by CD4+ T cells; one case showed both CD4+ and CD8+ T cells. In 17 cutaneous cases, scattered dermal CD20+ B cells were found individually or in small clusters within the background surrounding the neoplastic infiltrates. We concluded, therefore, that the immunophenotypic analysis of T-cell subpopulations using monoclonal antibodies of CD3, CD4, CD5, and CD8 was useful for histologic evaluation and confirmation of MF lesions in paraffin-embedded tissue. These antibodies might also provide an effective method of immunophenotyping other neoplastic and non-neoplastic T-cell populations in paraffin-embedded tissues.
authors.affiliation: Department of Pathology, Loyola University Medical Center, Maywood, Illinois 60153, USA.
authors.forename: K F
authors.initials: KF
authors.lastname: Izban
authors.forename: E D
authors.initials: ED
authors.lastname: Hsi
authors.forename: S
authors.initials: S
authors.lastname: Alkan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000276:immunology; D016516:CD4-CD8 Ratio; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D016130:Immunophenotyping; D008198:Lymph Nodes / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009182:Mycosis Fungoides / Q000276:immunology* / Q000473:pathology; D016612:Paraffin Embedding; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000276:immunology* / Q000473:pathology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD