Comprehensive characterization of pleomorphic adenoma at intraoral unusual sites

The present study aimed to comprehensively characterize the epidemiologic characteristics, clinicopathologic characteristics, clinical treatments, and prognoses of pleomorphic adenoma (PA) identified at unusual intraoral sites.

Patients diagnosed with PA in oral and maxillofacial regions at our institution in the past 16 years (2005-2020) were screened from the inpatient disease registry. All data concerning patients with PA found at unusual intraoral sites (defined as intraoral locations except sublingual gland and palate) were retrieved. Previously published cases with adequate clinicopathologic data were collected from PubMed and Embase. Eligible cases were further reviewed and included for statistical analyses.

Among 1039 cases of PA diagnosed at our institution, 52 lesions were found at unusual intraoral sites. A literature review identified another 63 eligible cases from 32 articles. The upper lip was the most common sites for these lesions (n = 57), followed by buccal mucosa (n = 34), tongue (n = 8), lower lip (n = 8), and retromolar area (n = 2). Recurrence and malignant transformation after surgical resection were extremely rare for these lesions.

PA might rarely develop at uncommon intraoral sites with atypical presentations, thus complicating its early diagnosis. Surgical resection is the major therapeutic strategy for this rare entity and has a favorable prognosis.