title: Precancerous foci in pleomorphic adenoma of the salivary gland: recognition of focal carcinoma and atypical tumor cells by P53 immunohistochemistry.
abstract: BACKGROUND
  It is still controversial if atypical tumor cells scattered in salivary pleomorphic adenomas are precancerous and how carcinoma arises in pleomorphic adenomas.
  
  
  METHODS
  We studied clinicopathologically the frequency and variation of cellular atypia among tumor cells and examined the expression status of p53 gene products as well as proliferating cell nuclear antigen (PCNA) in 101 surgical materials of pleomorphic adenomas.
  
  
  RESULTS
  Histopathologically, atypical tumor cells were found in 51% of the cases examined. Their mode of distribution was classified into three groups: focal (six cases, 6%) which could be identified as focal carcinoma, measuring less than 1 mm in diameter; sporadic (15 cases, 15%) and singular (30 cases, 30%). These atypical cells were located mainly within sheet-like nests of tumor cells but not in chondroid or fibro-hyaline foci. Immunohistochemically, most of the atypical cells were positive for p53 gene products and PCNA.
  
  
  CONCLUSIONS
  The results indicated that atypical cells with p53 protein accumulation in their nuclei could be regarded as cells in a precancerous state not yet forming an apparent carcinomatous nest. Some cell population with these atypical cells are likely to form focal carcinomas and then to an apparent form of carcinoma in pleomorphic adenoma.
authors.affiliation: Division of Oral Pathology, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Ohtaké
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ida
authors.forename: Makoto
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Ohshiro
authors.forename: Weiguo
authors.initials: W
authors.lastname: Zhang
authors.forename: Takashi
authors.initials: T
authors.lastname: Saku
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D008949:Adenoma, Pleomorphic / Q000378:metabolism / Q000473:pathology*; D000704:Analysis of Variance; D002471:Cell Transformation, Neoplastic; D006801:Humans; D007124:Immunoenzyme Techniques; D009363:Neoplasm Proteins / Q000096:biosynthesis; D011230:Precancerous Conditions / Q000378:metabolism / Q000473:pathology*; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis; D012468:Salivary Gland Neoplasms / Q000378:metabolism / Q000473:pathology*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis
chemical_list: D009363:Neoplasm Proteins; D018809:Proliferating Cell Nuclear Antigen; D016159:Tumor Suppressor Protein p53