Ten Years of Parotid Gland Tumors: Regional Data from Bulgaria

Background: Demographic patterns of parotid gland tumors (PGTs) vary across regions and over time, which is important for clinical practice. We aimed to characterize the epidemiology of PGTs in seven regions from northeastern and north-central Bulgaria, focusing on patient demographics, laterality, benign–malignant distribution, histologic subtypes and temporal incidence. Methods: A retrospective descriptive study was conducted at a single university maxillofacial surgery clinic in Bulgaria. Cases were reviewed over a 10-year period (1 January 2015–31 December 2024). Age, sex, histology, and benign/malignant status were recorded. Group differences were assessed with t-tests and χ² tests. Annual crude benign, malignant and total parotid tumor incidence rates of per 100,000 population were calculated (2015–2024). Results: Benign tumors constituted 86.4% (312/361) and malignant 13.6% (49/361). Patients with benign tumors were significantly younger than those with malignancy (56.5 ± 14.2 vs 65.4 ± 14.3 years; t = −4.1; p < 0.001). The proportion of malignancy increased with age (χ² = 22.965; p < 0.001). Among benign neoplasms, Warthin’s tumor (WT) was most frequent (44.9%), followed by pleomorphic adenoma (PA) (34.3%); WT predominated in men and PA in women (p < 0.001). In children, PA was the only benign entity identified. Among malignancies, salivary duct carcinoma and adenoid cystic carcinoma were most common (18.4% each), with mucoepidermoid carcinoma close behind (16.3%); when pooled, malignant tumors showed no significant associations with sex or age. Crude annual incidence rates for benign PGTs rose from 1.50 (2015) to 3.48 per 100 000 in 2023, (p=0.002). Malignant rates varied without a clear trend, (p=0.25) and total PGT incidence increased significantly from 1.79 (2015) to 3.80 per 100 000 in 2023, (p=0.001). Conclusions: In this single-center study, most PGTs were benign (86.4%); benign cases presented younger, and the likelihood of malignancy increased with age. WT predominated, especially in men, whereas PA was more common in women and was the only diagnosed pediatric tumor; malignancies were mainly salivary duct carcinoma and adenoid cystic carcinoma (with mucoepidermoid carcinoma being also common) with no sex/age associations, and crude incidence rose over time for benign and total tumors but not for malignant entities.