title: Unusual expression of S-100 protein in histiocytic neoplasms.
abstract: Twenty-nine cases of histiocytic neoplasms, some resembling juvenile xanthogranuloma (JXG) and others resembling reticulohistiocytoma (RH), were evaluated. Immunohistochemical stains were performed. In this series, seven cases were identified that expressed S-100 protein positive cells. The S-100 positive cells were predominantly large mononuclear and multinucleated histiocytes with eosinophilic cytoplasm, but also in some cases xanthomatous cells and Touton giant cells. These cells also expressed a positive reaction for vimentin, KP-1, and Factor XIIIa. There was no reactivity observed for monoclonal antibody 010(CD1a). A positive reaction for S-100 protein is conventionally accepted as a useful differentiating feature between histiocytosis X and non-X histiocytosis such as JXG and RH. The conflicting results of the immunohistochemical stains in the lesions we studied could be potential pitfalls in diagnosing histiocytic neoplasms.
authors.affiliation: Department of Dermatopathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Tomaszewski
authors.forename: G P
authors.initials: GP
authors.lastname: Lupton
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D015616:Histiocytosis, Non-Langerhans-Cell / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008875:Middle Aged; D009418:S100 Proteins / Q000378:metabolism*; D012871:Skin Diseases / Q000378:metabolism* / Q000473:pathology; D013194:Staining and Labeling; D014972:Xanthogranuloma, Juvenile / Q000378:metabolism* / Q000473:pathology
chemical_list: D009418:S100 Proteins