title: Immunohistochemical and ultrastructural observations of desmoplastic trichoepithelioma with a special reference to a morphological comparison with normal apocrine acrosyringeum.
abstract: BACKGROUND
  Desmoplastic trichoepithelioma is a benign neoplasm considered to have follicular differentiation. Its sweat gland- or sebaceous-lines of differentiation have been also reported. There have been, however, only a few reports regarding extensive immunohistochemical and ultrastructural investigations of this neoplasm.
  
  
  METHODS
  Histopathological and immunohistochemical studies were performed on three cases of desmoplastic trichoepithelioma, comparing it with normal skin. One of these cases was ultrastructurally investigated.
  
  
  RESULTS
  The cord-like basaloid nests were reacted with the anti-cytokeratin (CK)1/5/10/14, -CK5/8, -CK14 and -CK15 antibodies, but not with the anti-CK6 antibody. Similar findings were observed in the outer layers of the normal follicular outer root sheath. Basaloid cell nests in one case, which showed ductal structures in the nests, also expressed CK7, CK8/18 and CK19. These keratins were also detected in the normal sweat glands. In addition, CK8/18 and CK19 were expressed in the basal cells of the outer root sheath. Keratinous cysts had inner reactions with the anti-CK10/11 and -CK6 antibodies, and outer reactions with anti-CK5/8 and -CK14 antibodies. Ultrastructurally, the cells in the cord-like nests were basically immature and basaloid in appearance. A few cells contained Odland bodies, which were also observed in the normal apocrine acrosyringeum. The ductal structure was lined by the cells which bore numerous microvilli in the luminal surface.
  
  
  CONCLUSIONS
  The cells in desmoplastic trichoepithelioma are suggested to be in close association with the basal cells in the outer root sheath, which can differentiate into various parts of the folliculosebaceous apocrine unit.
authors.affiliation: Department of Dermatology and Occupational Dermatopathology, School of Medicine, University of Occupational and Environmental Health Japan, Kitakyushu, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamamoto
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hamada
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Doi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Sasaguri
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashimoto
mesh_terms: D000293:Adolescent; D000328:Adult; D001050:Apocrine Glands / Q000378:metabolism / Q000648:ultrastructure*; D014408:Biomarkers, Tumor / Q000378:metabolism; D002648:Child; D005260:Female; D018859:Hair Follicle / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018295:Neoplasms, Basal Cell / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor