title: Keratoacanthoma: clinical and histopathologic features of regression.
abstract: BACKGROUND
  The clinical and histopathologic features of regressing keratoacanthomas have not been adequately described in the literature.
  
  
  OBJECTIVE
  "True" keratoacanthomas (ie, squamous tumors with evidence of spontaneous resolution) were studied clinically and histopathologically.
  
  
  METHODS
  Nineteen crateriform tumors with a partial biopsy histopathologically compatible with keratoacanthoma were followed over time for correlation with biologic behavior (ie, regression). Tumors displaying spontaneous resolution, arbitrarily defined as a decrease in size of at least 25%, were categorized as keratoacanthomas.
  
  
  RESULTS
  Seven regressing keratoacanthomas tended to show flattening before a decrease in diameter. Histopathologically, there was variable epidermal hyperplasia with generally prominent hyperkeratosis, retained crateriform architecture, and dermal fibrosis.
  
  
  CONCLUSIONS
  This study has a small sample size.
  
  
  CONCLUSIONS
  Regressing keratoacanthomas show persistent crateriform architecture, clinically and histopathologically. Lesions become flatter before decreasing in diameter, and keratinocytes appear banal and lack glassy pink cytoplasm during regression.
authors.affiliation: Yale University School of Medicine, New Haven, Connecticut, USA. christine.ko@yale.edu
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Ko
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: McNiff
authors.forename: Marcus
authors.initials: M
authors.lastname: Bosenberg
authors.forename: Keith A
authors.initials: KA
authors.lastname: Choate
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D015603:Keratinocytes / Q000473:pathology; D007636:Keratoacanthoma / Q000473:pathology*; D012871:Skin Diseases / Q000473:pathology*