title: An infiltrative variant of non-neural  granular cell tumor: a case report.
abstract: Dermal non-neural granular cell tumors are rare tumors of indeterminate lineage that typically present as well-circumscribed tumors with nuclear pleomorphism and mitotic activity. We describe a dermal non-neural granular cell tumor with a distinctive growth pattern with granular cells interspersed between collagen bundles. This asymptomatic papule arose on the scapula of a 46-year-old woman and consisted of a mixture of epithelioid and spindled granular cells. The immunohistochemical characteristics were similar to those of previously reported dermal non-neural granular cell tumors. Despite mild nuclear pleomorphism and dispersion of lesional cells among collagen bundles, mitoses were not present and Ki-67 staining indicated a low proliferative rate. In addition to being S-100 protein negative and NKI/C3 positive, our case was positive for PGP9.5 and weakly positive for neuron-specific enolase, a staining pattern similar to what has been observed for cellular neurothekeomas. Our case could represent a dermal non-neural granular cell tumor with unique architecture, a granular cellular neurothekeoma or a granular cell dermatofibroma. As both dermal non-neural granular cell tumor and cellular neurothekeoma are of indeterminate lineage, our case with features characteristic of both entities may suggest a common precursor or lineage for dermal non-neural granular cell tumor and cellular neurothekeoma.
authors.affiliation: Division of Dermatology, Department of Medicine, University of Washington, Seattle, WA 98195-6524, USA. iweiyeh@u.washington.edu
authors.forename: Iwei
authors.initials: I
authors.lastname: Yeh
authors.forename: Don T
authors.initials: DT
authors.lastname: Tran
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Davis
authors.forename: Zsolt B
authors.initials: ZB
authors.lastname: Argenyi
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D016586:Granular Cell Tumor / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D018219:Histiocytoma, Benign Fibrous / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D018321:Neurothekeoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D012540:Scapula / Q000473:pathology / Q000601:surgery; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
chemical_list: D014408:Biomarkers, Tumor