title: PHLDA1, a follicular stem cell marker, differentiates clear-cell/granular-cell trichoblastoma and clear-cell/granular cell basal cell carcinoma: a case-control study, with first description of granular-cell trichoblastoma.
abstract: BACKGROUND
  Granular-cell or clear-cell basal cell carcinomas (BCCs), and clear-cell trichoblastomas have rarely been reported in the literature. PHLDA1 is a follicular stem cell marker, the expression of which has been reported to differentiate trichoepithelioma from BCCs. We wondered whether (1) granular-cell trichoblastoma exists and (2) PHLDA1 expression can differentiate a clear- and/or granular-cell trichoblastoma and a BCC.
  
  
  METHODS
  In the records of 2 pathology departments, 12 clear- and/or granular-cell trichoblastomas and BCCs were found. Epidemiological, histopathological, and immunohistochemical data for PHLDA1, Ki67, and AE1-AE3; and cytokeratins 17, 19, 20, and 6hf were collected.
  
  
  RESULTS
  Trichoblastomas and clear- and/or granular-cell BCCs occurred in 7 patients (36-62 years; mean: 49) and in 5 patients (63-91 years; mean: 77), respectively. Three granular-cell trichoblastomas were identified. Both granular and clear-cell changes were present in 4 BCCs. The patterns of expression for AE1/AE3, CK17, CK19, CK6hf, and CK20 were not helpful in differentiating trichoblastoma from BCC. PHLDA1 expression was diffusely or partially present in all trichoblastomas (5/5) and absent in BCCs (0/4) (P = 0.008).
  
  
  CONCLUSIONS
  Granular- and/or clear-cell changes are rare findings in trichoblastoma and BCC. First, we show that granular-cell trichoblastomas do occur. Second, PHLDA1 expression is a useful addition in differentiating trichoblastoma and BCC.
authors.affiliation: *Université Paris Diderot, Sorbonne Paris Cité, Laboratoire de Pathologie, Paris, France; †INSERM, Paris, France; ‡AP-HP-Hôpital Saint-Louis, Laboratoire de Pathologie, Paris, France; §Université Louis Pasteur, Strasbourg, France; and ¶Laboratoire d'Histopathologie Cutanée, Clinique Dermatologique, Hôpitaux Universitaires de Strasbourg, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Battistella
authors.forename: Bernard
authors.initials: B
authors.lastname: Peltre
authors.forename: Bernard
authors.initials: B
authors.lastname: Cribier
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D002280:Basal Cell Carcinoma / Q000737:chemistry* / Q000473:pathology; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D005602:France; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018294:Neoplasms, Adnexal and Skin Appendage / Q000737:chemistry* / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000737:chemistry* / Q000473:pathology; D011237:Predictive Value of Tests; D012878:Skin Neoplasms / Q000737:chemistry* / Q000473:pathology; D014157:Transcription Factors / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; C491923:PHLDA1 protein, human; D014157:Transcription Factors