title: Expression of MiTF may be helpful in differentiating cellular neurothekeoma from plexiform fibrohistiocytic tumor (histiocytoid predominant) in a partial biopsy specimen.
abstract: BACKGROUND
  Overlapping histopathologic features of cellular neurothekeoma (CNT) and plexiform fibrohistiocytic tumor (PFHT), when both are predominantly composed of histiocytoid cells, make distinction between these entities challenging. Some have suggested that CNT and PFHT are related entities. No prior study has demonstrated a reliable immunohistochemical panel to differentiate these entities.
  
  
  METHODS
  Skin biopsies diagnosed as CNT and PFHT, from 2004 to 2010 were retrieved with accompanying pathology reports. Each case was reviewed by at least 2 dermatopathologists and 2 soft tissue pathologists for confirmation of diagnosis. All cases were then evaluated for immunohistochemical expression of PAX2, NKIC3, CD10, and microphthalmia transcription factor (MiTF).
  
  
  RESULTS
  Histopathologically, the histiocytoid areas of each tumor shared similar architecture, demonstrating nests and fascicles of histiocytoid to spindled cells, with some separation of nests by collagen bands. Both CNT and PFHT were uniformly positive for NKIC3 and CD10, and both were frequently PAX2 positive. MiTF was strongly and diffusely positive in CNT and was consistently negative in the PFHT.
  
  
  CONCLUSIONS
  CNT and PFHT share many histopathologic features and immunohistochemical staining patterns. Of the stains we evaluated, we found that expression of MiTF may be a reliable marker for distinguishing CNT from histiocytoid-predominant PFHT, especially in instances where only a small part of the tumor is sampled for evaluation.
authors.affiliation: Department of Pathology, NorthShore University HealthSystem, Evanston, IL 60201, USA.
authors.forename: Melanie D
authors.initials: MD
authors.lastname: Fox
authors.forename: Steven D
authors.initials: SD
authors.lastname: Billings
authors.forename: Briana C
authors.initials: BC
authors.lastname: Gleason
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Moore
authors.forename: Antoinette B
authors.initials: AB
authors.lastname: Thomas
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Shea
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Victor
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Cibull
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051739:Microphthalmia-Associated Transcription Factor / Q000032:analysis / Q000096:biosynthesis*; D008875:Middle Aged; D018318:Neurofibroma, Plexiform / Q000175:diagnosis* / Q000378:metabolism; D018321:Neurothekeoma / Q000175:diagnosis* / Q000378:metabolism; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; C497234:MITF protein, human; D051739:Microphthalmia-Associated Transcription Factor