title: A benign cutaneous plexiform hybrid tumor of perineurioma and cellular neurothekeoma.
abstract: There are several recent reports describing hybrid peripheral nerve sheath tumors showing a biphasic component of neoplastic cells. These combinations include a mixture of neurofibroma and schwannoma, schwannoma and perineurioma, neurofibroma and perineurioma, and perineurioma and granular cell tumor. A case of a triphasic combination of neurofibroma, schwannoma, and perineurioma has also been described. We describe the clinicopathologic and immunohistochemical characteristics of 9 cases of a benign cutaneous plexiform nerve sheath tumor located on the lips and exhibiting hybrid features of perineurioma and cellular neurothekeoma. Clinically, lesions were solitary dome-shaped papules located on the lips. Histopathologically, the neoplasms consisted of well-circumscribed but uncapsulated dermal nodules with a plexiform pattern. They were composed of nests or rounded aggregations of neoplastic cells embedded in a slightly myxoid stroma. Within the aggregates, cells were distributed in a storiform and lamellar pattern. Immunohistochemically, most neoplastic cells expressed strong immunoreactivity for S100A6, MiTF, NKI/C3, PGP9.5, EMA, and NSE, whereas variable, focal, and weaker positivity for CD34, claudin-1, and Glut-1 was seen in some cases. On the basis of these findings, we believe that this neoplasm is a distinctive benign cutaneous plexiform nerve sheath tumor with histopathologic and immunohistochemical hybrid features of perineurioma and cellular neurothekeoma.
authors.affiliation: Department of Dermatology, Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain. lrequena@fjd.es
authors.forename: Luis
authors.initials: L
authors.lastname: Requena
authors.forename: Panitta
authors.initials: P
authors.lastname: Sitthinamsuwan
authors.forename: Isabella
authors.initials: I
authors.lastname: Fried
authors.forename: Steven
authors.initials: S
authors.lastname: Kaddu
authors.forename: Carl Georg
authors.initials: CG
authors.lastname: Schirren
authors.forename: Leo
authors.initials: L
authors.lastname: Schärer
authors.forename: Markus
authors.initials: M
authors.lastname: Hantschke
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cerroni
authors.forename: Timothy H
authors.initials: TH
authors.lastname: McCalmont
authors.forename: Heinz
authors.initials: H
authors.lastname: Kutzner
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008048:Lip Neoplasms / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D018193:Neoplasms, Complex and Mixed / Q000378:metabolism / Q000473:pathology*; D018317:Nerve Sheath Neoplasms / Q000378:metabolism / Q000473:pathology*; D018321:Neurothekeoma / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor