title: Leu-M1 antigen expression in advanced (tumor) stage mycosis fungoides.
abstract: The authors describe two patients with clinically and histopathologically documented advanced (tumor) stage mycosis fungoides. In each case the large, pleomorphic neoplastic cells lacked the monoclonal antibody-defined cell surface antigens commonly associated with immature and mature T-cells, i.e., T11, Leu-1, T3, T4, T6, T8, and T10, but expressed various T-cell-associated activation antigens, such as HLA-DR, Tac, and T21. Leu-M1, a monocyte-associated antigen, was not expressed by the small, cerebriform neoplastic cells in the plaque stage lesions of either patient. However, Leu-M1 was expressed by most of the large, pleomorphic neoplastic cells present in the nodular lesions of both patients. The pattern of Leu-M1 antigen expression was identical to that previously reported in the Reed-Sternberg cells of Hodgkin's disease. Identification of these two patients suggests using caution in the interpretation of the results of immunophenotypic analysis of cutaneous lymphoid neoplasms and that Leu-M1 should not be used as a diagnostic indicator of Hodgkin's disease or a histiocytic-derived neoplasm. These studies also suggest that Leu-M1 may be preferentially expressed on a subpopulation of activated, rapidly proliferating, and/or dedifferentiated neoplastic T-cells that proliferate in the advanced (tumor) stages of mycosis fungoides.
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009182:Mycosis Fungoides / Q000276:immunology* / Q000473:pathology; D010641:Phenotype; D012867:Skin / Q000648:ultrastructure; D012878:Skin Neoplasms / Q000276:immunology* / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; D000954:Antigens, Surface