title: Immunohistochemical analysis of KBA.62 in 18 neurothekeomas: a potential marker for differentiating neurothekeoma, but a marker that may lead to confusion with melanocytic tumors.
abstract: BACKGROUND
  Neurothekeoma represents a neoplasm of uncertain histogenesis that often occurs on the head and neck of younger individuals. Distinguishing neurothekeoma from other tumors, particularly malignancies such as melanoma, can be difficult given the variable presence of nuclear atypia, mitoses and extension into fat or skeletal muscle. KBA.62 represents an anti-melanoma monoclonal antibody that marks approximately 93% of melanomas. This study sought to evaluate KBA.62 expression in neurothekeomas, both as means of affirming the diagnosis and as a potential confounding factor in excluding a melanocytic process.
  
  
  METHODS
  Eighteen neurothekeomas from 17 patients were analyzed by light microscopy and immunohistochemistry. Immunohistochemistry was performed with KBA.62, S100 and CD10 antibodies. The diagnosis of neurothekeoma was confirmed by at least two dermatopathologists.
  
  
  RESULTS
  All cases showed similar light microscopic and immunohistochemical features. With the exception of two cases, cells expressed CD10 and exhibited morphologic features consistent with neurothekeoma. All 18 cases were S100 immunonegative. The epithelioid cells of all neurothekeomas were KBA.62 immunopositive, including both of two neurothekeomas occurring in the same patient.
  
  
  CONCLUSIONS
  In this study 100% of neurothekeomas tested were KBA.62 positive, admittedly to varying degrees, suggesting the utility of this reagent as being supportive of the diagnosis of neurothekeoma.
authors.affiliation: Department of Dermatology, New York Presbyterian Hospital/Weil Cornell Medical Center, New York, NY, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Suarez
authors.forename: Whitney A
authors.initials: WA
authors.lastname: High
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D018321:Neurothekeoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; C588000:KBA.62 monoclonal antibody, human
keywords: cellular neurothekeoma; immunocytochemistry; immunopathology