title: Differential expression of PHLDA1 (TDAG51) in basal cell carcinoma and trichoepithelioma.
abstract: BACKGROUND
  A recent small series demonstrated perfect sensitivity and specificity utilizing immunostaining for PHLDA1, a marker of follicular stem cells, in the distinction of desmoplastic trichoepithelioma and morphoeiform basal cell carcinoma (BCC) in small biopsy specimens.
  
  
  OBJECTIVE
  To assess this result more broadly.
  
  
  METHODS
  We performed immunoperoxidase staining of BCCs (superficial n = 16, nodular n = 15, micronodular n = 15, infiltrative n = 17, morphoeiform n = 16, infundibulocystic n = 14) and trichoepitheliomas (conventional n = 19, desmoplastic n = 16) with PHLDA1.
  
  
  RESULTS
  Morphoeiform BCCs typically lacked PHLDA1 staining (88% demonstrated no staining and 12% of cases had staining in < 25% of the tumour), while in contrast 74% of classical and 88% of desmoplastic trichoepitheliomas demonstrated strong PHLDA1 staining in over half of the tumour. However, micronodular BCCs demonstrated focal to diffuse positive staining in a third of the cases.
  
  
  CONCLUSIONS
  Based upon our staining results, we discuss the biological significance of PHLDA1 expression and the limits in its diagnostic utility.
authors.affiliation: Departments of Dermatology and Pathology, University of California, San Francisco, CA, USA. iwei.yeh@gmail.com
authors.forename: I
authors.initials: I
authors.lastname: Yeh
authors.forename: T H
authors.initials: TH
authors.lastname: McCalmont
authors.forename: P E
authors.initials: PE
authors.lastname: LeBoit
mesh_terms: D014408:Biomarkers, Tumor / Q000276:immunology / Q000378:metabolism; D002280:Basal Cell Carcinoma / Q000378:metabolism* / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D011237:Predictive Value of Tests; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; C491923:PHLDA1 protein, human; D014157:Transcription Factors