title: Trichilemmoma: an immunohistochemical study of cytokeratins.
abstract: BACKGROUND
  The histogenesis of trichilemmoma remains unclear.
  
  
  OBJECTIVE
  To clarify the histogenesis of trichilemmoma by evaluating its cytokeratin (CK) expression.
  
  
  METHODS
  In three cases of trichilemmoma, CK expression was studied immunohistochemically using seven antikeratin antibodies against CK1, 10, 14-17 and 19, respectively.
  
  
  RESULTS
  CK1 and CK10 were present in keratinizing ductal epithelium. CK14 was present in the whole layer. CK15 was present in suprabasal layers in two cases. CK16 was present in the suprabasal layer, but was absent in keratinizing ductal epithelium. CK17 was present in suprabasal layers and the sebaceous duct-like structure. CK19 was totally absent.
  
  
  CONCLUSIONS
  These results showed that trichilemmoma may differentiate mainly towards two directions: infundibular keratinization and proliferation of the outer root sheath with undifferentiated and pluripotent characteristics.
authors.affiliation: Department of Dermatology, Hyogo Prefectural Tsukaguchi Hospital, 6-8-17, Minamitsukaguchi-cho, Amagasaki, Hyogo 661-0012, Japan. ikuro@aa.alles.or.jp
authors.forename: I
authors.initials: I
authors.lastname: Kurokawa
authors.forename: S
authors.initials: S
authors.lastname: Nishijima
authors.forename: K
authors.initials: K
authors.lastname: Kusumoto
authors.forename: H
authors.initials: H
authors.lastname: Senzaki
authors.forename: N
authors.initials: N
authors.lastname: Shikata
authors.forename: A
authors.initials: A
authors.lastname: Tsubura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002280:Basal Cell Carcinoma / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D005260:Female; D006201:Hair Diseases / Q000378:metabolism / Q000473:pathology; D018859:Hair Follicle; D006801:Humans; D007633:Keratins / Q000378:metabolism*; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D009363:Neoplasm Proteins; D007633:Keratins