title: Immunohistochemical markers in fibrohistiocytic lesions: factor XIIIa, CD34, S-100 and p75.
abstract: BACKGROUND
  The distinction between dermatofibroma (DF), dermatofibrosarcoma protuberans (DFSP), and other benign and malignant cutaneous spindle cell lesions frequently requires immunohistochemical staining. CD34 and factor XIIIa are the most commonly used immunostains; however, they may exhibit aberrant expression and introduce the potential for misdiagnosis. There is some data supporting that p75 and S100A6 may be additional helpful immunohistochemical markers.
  
  
  METHODS
  We undertook a large case series examining the use of CD34 and factor XIIIa as well as p75 and S100A6 in DF, cellular DF, DFSP, indeterminate fibrohistiocytic lesion, and scar.
  
  
  RESULTS
  As expected, CD34 stained DFSP, although it was usually negative in DF. Factor XIIIa was generally positive in DF and negative in DFSP. There were exceptions in both cases of DF and DFSP. S100A6 was routinely negative in all entities studied. P75 was negative in all cases except DFSP, approximately half of which showed weak and/or patchy positivity.
  
  
  CONCLUSIONS
  We conclude that to date, CD34 and factor XIIIa remain the most reliable immunohistochemical markers for DF and DFSP.
authors.affiliation: *Department of Pathology. Duke University Medical Center, Durham, NC; and †Laboratory Corporation of America, Center for Molecular Biology and Pathology, Research Triangle Park, NC.
authors.forename: Kelly L
authors.initials: KL
authors.lastname: West
authors.forename: Diana M
authors.initials: DM
authors.lastname: Cardona
authors.forename: Zuowei
authors.initials: Z
authors.lastname: Su
authors.forename: Puja K
authors.initials: PK
authors.lastname: Puri
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D018223:Dermatofibrosarcoma / Q000175:diagnosis*; D003937:Diagnosis, Differential; D026122:Factor XIIIa / Q000032:analysis; D018219:Histiocytoma, Benign Fibrous / Q000175:diagnosis*; D006801:Humans; D007150:Immunohistochemistry; D009419:Nerve Tissue Proteins / Q000032:analysis; D017475:Receptors, Nerve Growth Factor / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D012878:Skin Neoplasms / Q000175:diagnosis*
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; C484065:NGFR protein, human; D009419:Nerve Tissue Proteins; D017475:Receptors, Nerve Growth Factor; D009418:S100 Proteins; D026122:Factor XIIIa