title: CD10, p63 and CD99 expression in the differential diagnosis of atypical fibroxanthoma, spindle cell squamous cell carcinoma and desmoplastic melanoma.
abstract: BACKGROUND
  Atypical fibroxanthoma (AFX) is a pleomorphic spindle cell lesion of the skin; it is considered in the differential diagnosis with spindle cell malignant melanoma (MM) and sarcomatoid carcinoma/spindle cell squamous cell carcinoma (SCC). An optimum approach has yet to fully emerge with respect to the immunohistochemical discrimination of these lesions.
  
  
  METHODS
  Departmental archives from 1978 onwards were searched for clinicopathologically confirmed cases of AFX, MM and SCC. Immunostains for CD10, CD99 and p63 were performed in each case. Scored staining results were analyzed using Fisher's Exact Test.
  
  
  RESULTS
  Twenty-seven of 31 cases of AFX were positive for CD10, as compared with 3 of 22 SCCs and 0 of 20 MMs. CD10 positivity was preferentially associated with the diagnosis of AFX (p < 0.001). p63 reactivity was observed in 15/22 cases of SCCs, 5/31 AFXs and 1/20 MMs. CD99 reactivity was observed in 3/31 cases of AFX, 2/22 SCCs and 3/20 MMs.
  
  
  CONCLUSIONS
  CD10 positivity is relatively specific in this context for the diagnosis of AFX. Its utility is enhanced when only strong, diffuse membranocytoplasmic staining is considered as a positive result. In contrast to prior reports, p63 was not found to be highly sensitive for SCC. Similarly, CD99 showed no preferential staining of any single diagnostic group of lesions.
authors.affiliation: Department of Pathology, University of Virginia Health System, Charlottesville, VA 22908-0214, USA. wk3g@virginia.edu
authors.forename: William A
authors.initials: WA
authors.lastname: Kanner
authors.forename: Louis B
authors.initials: LB
authors.lastname: Brill
authors.forename: James W
authors.initials: JW
authors.lastname: Patterson
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wick
mesh_terms: D000071443:12E7 Antigen; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000096:biosynthesis; D014408:Biomarkers, Tumor / Q000032:analysis*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D003937:Diagnosis, Differential; D005260:Female; D018219:Histiocytoma, Benign Fibrous / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis; D008875:Middle Aged; D015260:Neprilysin / Q000096:biosynthesis; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C061828:CD99 protein, human; C081876:CKAP4 protein, human; D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D015260:Neprilysin