title: Keratoacanthoma arising after site injection infection of cosmetic collagen filler.
abstract: BACKGROUND
  Over one million treatments in more than 40 countries have been administered Zyplast implants. Infections at collagen implant sites have occurred in fewer than one per thousand treated patients.
  
  
  METHODS
  We present a case report of a 27-year-old man; he developed a severe granulomatous reaction in the site of resolvable collagen filler injection Zyplast, and one month later developed a cutaneous nodular lesion. Histological examination of the lesion revealed Keratoacanthoma (KA) with surgical margins free of tumor. We performed two surgical corrections within a period of six months on multiple hypertrophic skin scars of the face. Two years after the last excision, the patient continued to be free of any recurrence.
  
  
  CONCLUSIONS
  Keratoacanthoma (KA) is a benign skin tumor with a quick growth pattern but may regress spontaneously. Though the exact etiology of KA is uncertain, it is found to be more frequent in elderly people, on photo-exposed skin areas and cutaneous infection site. Bovine collagen intradermal injections, though catabolized over the time in the patient, can raise several complications already described in technical literature, but we want underline that cutaneous infection near filler injection site can develope KA as described in our case report.
  
  
  CONCLUSIONS
  KA must be considered as a new local unforeseeable complication of bovine collagen injection to fill facial soft tissue when occurred a face cutaneous infection. We believe that radical excision is the golden standard.
authors.affiliation: Unit of Plastic Reconstructive Surgery, Department of Orthopaedic, Traumatologic, Riabilitative and Plastic-Reconstructive Sciences, Policlinico Hospital of Second University of Naples, Naples, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Brongo
authors.forename: Luigi S
authors.initials: LS
authors.lastname: Moccia
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Nunziata
authors.forename: Francesco
authors.initials: F
authors.lastname: D'Andrea