title: Multiple keratoacanthomas arising post-UVB therapy.
abstract: BACKGROUND
  Ultraviolet (UV) radiation is known to be an important etiologic agent in the development of skin cancer. Keratoacanthoma is an unusual, well-described cutaneous neoplasm that resembles squamous cell carcinoma but spontaneously resolves. Rarely, multiple keratoacanthomas may develop.
  
  
  OBJECTIVE
  We present a case of multiple keratoacanthomas in a patient with psoriasis who had received UVB phototherapy. These lesions were hyperkeratotic papules, many of which spontaneously resolved and demonstrated the histologic characteristics of keratoacanthoma.
  
  
  CONCLUSIONS
  We believe that UV radiation is the most likely etiologic factor in this patient's development of multiple keratoacanthomas. We wish to bring to the attention of clinicians this unusual adverse effect of UV treatment.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Craddock
authors.forename: Jaggi
authors.initials: J
authors.lastname: Rao
authors.forename: Gilles J
authors.initials: GJ
authors.lastname: Lauzon
authors.forename: Victor A
authors.initials: VA
authors.lastname: Tron
mesh_terms: D000368:Aged; D006801:Humans; D007636:Keratoacanthoma / Q000209:etiology*; D008297:Male; D011565:Psoriasis / Q000628:therapy; D012871:Skin Diseases / Q000209:etiology*; D014467:Ultraviolet Therapy / Q000009:adverse effects*