title: Histomorphologic and immunophenotypic analysis of fibrofolliculomas and trichodiscomas in Birt-Hogg-Dube syndrome and sporadic disease.
abstract: BACKGROUND
  Fibrofolliculomas and trichodiscomas are benign dermal neoplasms that likely derive from the mantle of the hair follicle and can occur sporadically or in association with Birt-Hogg-Dube syndrome (BHDS). Little is known about the pathogenesis and immunophenotypic properties of these entities.
  
  
  METHODS
  We investigated the histomorphologic and immnophenotypic properties of 15 fibrofolliculomas and trichodiscomas in two patients with BHDS and eight with sporadic disease.
  
  
  RESULTS
  We found the following: (1) fibrofolliculomas and trichodiscomas occurring in the setting of BHDS show microscopically contiguous histomorphologic features as compared to those occurring sporadically; (2) the immunophenotypic characteristics of syndromic-associated and sporadic types are identical and consist of (3) perifollicular vimentin (+), CD34 (+) and Factor XIII (-) spindle cells.
  
  
  CONCLUSIONS
  Despite subtle histomorphologic differences, trichodiscomas and fibrofolliculomas are immunophenotypically similar, and are thus likely derived from a similar histogenic precursor. Given the previously reported CD34 (+) immunophenotype of the hair mantle, our findings would support an origin of these lesions from the mantle of the hair follicle. The proliferation of CD34 (+) spindle cells seen in conjunction with these lesions should not be confused with other CD34 (+) dermal entities.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D005260:Female; D005350:Fibroma / Q000737:chemistry / Q000473:pathology*; D006201:Hair Diseases; D018859:Hair Follicle / Q000737:chemistry / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D009378:Neoplasms, Multiple Primary / Q000737:chemistry / Q000473:pathology*; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology*; D013577:Syndrome
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins