Abstract
BACKGROUND: The synchronous development of multiple, histologically distinct primary salivary gland tumors is exceedingly rare, especially with involvement of both major and minor glands. Although growing research has advanced epidemiological understanding, clinical management continues to be significantly impeded by underdiagnosis and misdiagnosis. CASE PRESENTATION: We present an 18-year-old female with two slow-growing, asymptomatic masses over a two-year period. The palatal mass showed gradual enlargement and mucosal protrusion. In contrast, the sublingual mass grew more rapidly, becoming fixed and immobile within the past year. Magnetic resonance imaging (MRI) revealed corresponding nodular soft-tissue masses with heterogeneous signals. The palatal lesion was irregular yet relatively well-defined; however, the sublingual mass displayed locally aggressive behavior with invasion of the mandibular lingual periosteum and floor-of-mouth muscles, resulting in ill-defined margins and submandibular duct dilation. Histopathologic correlation confirmed an intermediate-grade mucoepidermoid carcinoma of the sublingual gland and a pleomorphic adenoma of the palate. CONCLUSIONS: The synchronous occurrence of benign and malignant salivary gland tumors is a rare clinical phenomenon that demands thorough evaluation to ensure diagnostic accuracy and a favorable prognosis. We report a unique case of synchronous mucoepidermoid carcinoma in the sublingual gland and pleomorphic adenoma in the palate, which, to our knowledge, is the first such documented instance. This report expands the documented spectrum of multiple primary salivary gland tumors and serves as a vital clinical reference, underscoring the need for heightened awareness when assessing concurrent lesions.