Maxillofacial diagnostic features of the enigmatic metastasizing pleomorphic adenoma

Considering the confusion in the literature regarding local recurrence, spread, or metastases of pleomorphic adenoma (PA) in the head and neck region, the aim of this study was to enhance understanding of the characteristics of metastasizing pleomorphic adenoma (MPA) by reviewing the literature and presenting a case. English language articles with proof of metastases were included in the literature review. Of the 80 cases in the literature with MPA, 46 were female and 33 were male (sex missing for one case). Thirty-five percent of the neoplasms affected the bones; the maxilla was affected in five cases and the mandible in three. The parotid was the primary site in 72.5% of cases and the submandibular gland in 16.2% of cases. The local recurrence rate was 70%. The mean interval between primary PA and MPA was 15.52 years. The total mortality rate was 8.7%. A case of PA of the submandibular gland that recurred after surgical excision and metastasized (confirmed by the presence of intact cortical borders) to the ipsilateral mandibular body, upper lip, and neck is described. The high mortality rate in a histologically defined benign disease that metastasizes demands that management include careful primary excision and long-term clinical follow-up.