title: The histopathology of closed and open comedones of Favre-Racouchot disease.
abstract: OBJECTIVE
  To determine the distinction between a comedo and an infundibular cyst of Favre-Racouchot disease.
  
  
  METHODS
  A university hospital.
  
  
  METHODS
  From the 8 patients included in the study, 19 cysts and comedones were evaluated.
  
  
  METHODS
  The distinguishing features between the cysts and comedones of Favre-Racouchot disease.
  
  
  RESULTS
  All lesions were histologically indistinguishable from the primary comedones of acne vulgaris, except for the presence of a marked actinic elastosis in the surrounding dermis. The presence of a variable number of hair shafts and an abundant amount of bacteria, which was positive in the results of Gram staining and periodic acid-Schiff reaction and intermingled with sebum and eosinophilic laminated horny material within the dilated infundibulum, characterizes a comedo and differentiates it from an infundibular cyst.
  
  
  CONCLUSIONS
  The cysts and comedones of Favre-Racouchot disease are closed and open comedones. They can be easily differentiated from an infundibular cyst by the histopathologic features rather than by the connection to the surface.
authors.affiliation: Department of Dermatology, Hospital Universitario San Carlos, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Sánchez-Yus
authors.forename: E
authors.initials: E
authors.lastname: del Río
authors.forename: P
authors.initials: P
authors.lastname: Simón
authors.forename: L
authors.initials: L
authors.lastname: Requena
authors.forename: H
authors.initials: H
authors.lastname: Vázquez
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005148:Facial Dermatoses / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged