title: Benign metastasizing pleomorphic adenoma of the parotid gland: a clinicopathologic puzzle.
abstract: BACKGROUND
  Pleomorphic adenoma constitutes the most common benign parotid gland tumor. Local recurrence after surgical treatment (lateral or total parotidectomy) has been described in 1% to 5% of cases. Malignant degeneration has been reported in 2% to 9% of cases of pleomorphic adenoma of salivary gland origin. Metastasizing pleomorphic adenomas without histologic evidence of malignancy have rarely been reported. Metastatic lesions have been discovered in bone, lymph nodes, the lung, oral cavity, pharynx, skin, liver, retroperitoneum, kidney, calvarium, and central nervous system. To the best of our knowledge, we hereby report the first case of pleomorphic adenoma of the parotid gland metastasizing to the ipsilateral maxilla.
  
  
  METHODS
  We simultaneously examined apoptosis-related protein expression and markers of cell-proliferation activity in our case of benign pleomorphic adenoma metastasis and compared outcome with a control group of primary parotid pleomorphic adenomas.
  
  
  RESULTS
  Analysis of p53, Bcl-2, MIB1, CD 105, p27, and p21 expression did not reveal significant differences between metastasizing pleomorphic adenoma of the salivary gland and the control group of primary parotid pleomorphic adenomas.
  
  
  CONCLUSIONS
  Clinical rather than pathologic evidence seems to justify inclusion of metastasizing salivary pleomorphic adenoma in the group of low-grade malignant salivary tumors.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Padua, Via Giustiani 2, Padua, Italy. g_marioni@virgilio.it
authors.forename: Gino
authors.initials: G
authors.lastname: Marioni
authors.forename: Filippo
authors.initials: F
authors.lastname: Marino
authors.forename: Roberto
authors.initials: R
authors.lastname: Stramare
authors.forename: Rosario
authors.initials: R
authors.lastname: Marchese-Ragona
authors.forename: Alberto
authors.initials: A
authors.lastname: Staffieri
mesh_terms: D008949:Adenoma, Pleomorphic / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D000328:Adult; D006801:Humans; D008297:Male; D008441:Maxillary Neoplasms / Q000378:metabolism / Q000556:secondary* / Q000601:surgery; D010307:Parotid Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery