title: Dermoscopic characteristics of nodular squamous cell carcinoma and keratoacanthoma.
abstract: BACKGROUND
  Nodular squamous cell carcinoma (SCC) and keratoacanthoma (KA) may mimic a variety of other benign and malignant non-pigmented nodules.
  
  
  OBJECTIVE
  To analyze the dermoscopic characteristics of nodular SCC and KA.
  
  
  METHODS
  Retrospective analysis of 50 nodular SCCs and 8 KAs collected from a tertiary dermatology referral center and a private dermatology practice in Melbourne, Australia, between 1 September 2009 and 1 October 2012. All lesions were nodules; defined as firm, elevated, round, palpable tumors with a diameter of 5 mm or more. Clinical and dermoscopic images were evaluated by two examiners in consensus.
  
  
  RESULTS
  Signs of keratinization were frequently observed and included keratin crust/scale (90% of SCCs, 100% of KAs), central keratin mass (32% of SCCs, 88% of KAs), white structureless areas (66% of SCCs, 50% of KAs), white circles (32% of SCCs, 38% of KAs) and white keratin pearls (14% of SCCs, 12% of KAs). Hemorrhage was present in 72% of SCCs and 88% of KAs and preferentially occurred centrally and in areas of keratinization. For nodular SCCs and KAs, we observed glomerular vessels (42% and 25% respectively), linear irregular vessels (36% and 25% respectively), atypical vessels (30% and 38% respectively) and hairpin vessels (30% and 25% respectively).
  
  
  CONCLUSIONS
  Hemorrhage, keratinization and vascular features (glomerular, hairpin and linear irregular morphologies) are useful in diagnosing both nodular SCC and KA. Further research on the comparative dermoscopic characteristics of a range of amelanotic nodules is important in order to improve diagnosis of these clinically challenging tumors.
authors.affiliation: Victorian Melanoma Service, Alfred Hospital, Melbourne, Australia.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Lin
authors.affiliation: Victorian Melanoma Service, Alfred Hospital, Melbourne, Australia.
authors.forename: Yan
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Victorian Melanoma Service, Alfred Hospital, Melbourne, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Jalilian
authors.affiliation: Victorian Melanoma Service, Alfred Hospital, Melbourne, Australia.
authors.forename: John W
authors.initials: JW
authors.lastname: Kelly
keywords: dermoscopy; diagnosis; keratoacanthoma; nodules; squamous cell carcinoma