title: Ameloblastic carcinoma developing in preexisting ameloblastoma with a mutation of the p53 gene: a case report.
abstract: OBJECTIVE
  Ameloblastic carcinoma is a rare malignant odontogenic tumor. Here we present a case of a large ameloblastic carcinoma, which developed in a preexisting ameloblastoma in the right submandibular region.
  
  
  METHODS
  The patient was an 84-year-old woman who had received several surgical procedures for ameloblastoma, including a segmental mandibulectomy. The dimensions of the tumor were 12 × 8 × 5 cm, and both benign ameloblastoma and ameloblastic carcinoma were observed histologically. Based on histologic diagnosis, immunohistochemical staining and sequence analysis for p53 were performed.
  
  
  RESULTS
  Overexpression of p53 was observed only in the ameloblastic carcinoma. Additionally, a mutation of the p53 gene (TP53) in exon 5 was found by sequence analysis in the ameloblastic carcinoma.
  
  
  CONCLUSIONS
  This is the first case of ameloblastic carcinoma with a mutation of the p53 gene that has been associated with carcinomatous transformation.
authors.affiliation: Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan; Department of Stomatology and Maxillofacial Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan. Electronic address: n.aiko@gunma-u.ac.jp.
authors.forename: Aiko
authors.initials: A
authors.lastname: Nobusawa
authors.affiliation: Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Sano
authors.affiliation: Department of Stomatology and Maxillofacial Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yokoo
authors.affiliation: Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Tetsunari
authors.initials: T
authors.lastname: Oyama
mesh_terms: D000369:Aged, 80 and over; D000564:Ameloblastoma / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D003952:Diagnostic Imaging; D005260:Female; D016158:Genes, p53; D006801:Humans; D007150:Immunohistochemistry; D008339:Mandibular Neoplasms / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D009154:Mutation; D009808:Odontogenic Tumors / Q000235:genetics* / Q000473:pathology / Q000601:surgery