title: Granular cell variant of epithelioid cell histiocytoma.
abstract: Classic granular cell tumors (GCTs) stain strongly and uniformly positive for S100 protein and are believed to show Schwann cell derivation. Polypoid cutaneous tumors composed of cells with large nuclei and abundant granular cytoplasm that do not stain for S100 protein or show apparent Schwannian differentiation have been reported by several groups under names including "primitive polypoid granular cell tumors," "dermal nonneural granular cell tumor," and "primitive nonneural granular cell tumors of skin." We report a polypoid tumor composed of S100-negative epithelioid cells with abundant eosinophilic granular cytoplasm that meets diagnostic criteria for (primitive polypoid dermal) nonneural GCT but also meets criteria for a granular cell variant of epithelioid cell histiocytoma. We have identified a single previous report of a similar lesion. We report the immunohistochemical characteristics of these lesions and address how they are best classified.
authors.affiliation: Rabkin Dermatopathology Laboratory, P.C., Tarentum, PA 15084, USA. msrabkin@gmail.com
authors.forename: Michael S
authors.initials: MS
authors.lastname: Rabkin
authors.forename: Tyler
authors.initials: T
authors.lastname: Vukmer
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D015622:Epithelioid Cells / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D005260:Female; D016586:Granular Cell Tumor / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D051642:Histiocytoma / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D009418:S100 Proteins / Q000032:analysis; D012867:Skin / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D012878:Skin Neoplasms / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D009418:S100 Proteins