title: Abortive keratoacanthoma: a hitherto unrecognised variant.
abstract: OBJECTIVE
  To study the histological features of abortive keratoacanthoma, a variant that has only recently been recognised.
  
  
  METHODS
  A key word search of the database of our pathology practice was carried out for all keratoacanthomas (KAs) reported by one author (DW) over a 14-month period. These cases were then sorted into histological subtypes by age in decades.
  
  
  RESULTS
  A total of 3465 cases of KA were reported over this period, of which 582 (16.8%) were of the so-called abortive type. Abortive KAs are characterised by rapid growth and subsequent lichenoid regression at an early stage in their evolution. Lichenoid changes extend for a variable distance beyond the lesion.
  
  
  CONCLUSIONS
  Abortive KA is a hitherto unrecognised variant of KA which may be misdiagnosed as squamous cell carcinoma despite its distinctive features. Lichenoid regression, rather than terminal differentiation, is the main mechanism of its involution.
authors.affiliation: Skin Laboratory, Sullivan Nicolaides Pathology, Taringa, Brisbane, Australia. d_weedon@snp.com.au
authors.forename: David
authors.initials: D
authors.lastname: Weedon
authors.forename: David
authors.initials: D
authors.lastname: Brooks
authors.forename: Jonathan
authors.initials: J
authors.lastname: Malo
authors.forename: Richard
authors.initials: R
authors.lastname: Williamson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007636:Keratoacanthoma / Q000473:pathology*; D008297:Male; D012871:Skin Diseases / Q000473:pathology*