Intraoral Minor Salivary Gland Tumors: A Retrospective, Clinicopathologic, Single-Center Study of 432 Cases in Japan and a Comparison with Epidemiological Data

BackgroundIntraoral minor salivary gland tumors are relatively rare lesions with histological subtypes not commonly found in major salivary glands. This study aimed to retrospectively evaluate the clinicopathologic features of intraoral minor salivary gland tumors from the Tokyo Dental College Hospital, Japan, and compare them with findings from other epidemiological studies.MethodsWe conducted a retrospective clinicopathologic evaluation of 432 cases of intraoral minor salivary gland tumors [161 male (37.3%) and 271 female (62.7%) patients; mean age: 52.5 and 48.6 years for males and females, respectively; age at diagnosis: 7-87 (mean: 50.1) years] from the Tokyo Dental College Hospital between 1975 and 2022, including 283 benign tumors (65.5%) and 149 malignant tumors (34.5%).ResultsThe most common benign tumor was pleomorphic adenoma (n = 239), whereas mucoepidermoid carcinoma was the most common malignant tumor (n = 74). The mean age of patients with benign and malignant tumors was 48.4 and 53.2 years, respectively, with patients with malignant tumors being significantly older (P = 0.0042). The mean age of patients with malignant tumors was significantly higher in males (56.7 years) than in females (50.9 years) (P = 0.0376), although the mean age of patients with benign tumors did not differ by sex. Tumors were commonly located in the palate [250 cases (57.9%)]. Benign tumors were more frequent in the palate, upper lip, and buccal mucosa, whereas malignant tumors were more frequent in the palate, floor of the mouth, buccal mucosa, and retromolar area.ConclusionsUnderstanding the features of intraoral minor salivary gland tumors is useful for diagnosis. Our study provides important epidemiological data (patient differences in age at occurrence, sex, and site of origin) that will inform clinicians and researchers.