Synchronous Pleomorphic Adenoma and Warthin Tumor in the Parotid Gland: MRI Findings of Structural Compartmentalization and Quantitative T2 Signal Differences.

Synchronous tumors of different histological origins within the same parotid gland are rare and can be difficult to diagnose preoperatively, particularly when imaging findings resemble a single multilobulated mass. Pleomorphic adenoma (PA) and Warthin tumor (WT) are the two most common benign parotid tumors; however, their ipsilateral coexistence is uncommon. We report a case of synchronous PA and WT in the superficial lobe of the left parotid gland in a 56-year-old male presenting with painless infra-auricular swelling. Magnetic resonance imaging (MRI) demonstrated a bilobed lesion. On T1-weighted imaging, the mass appeared morphologically unified. In contrast, T2-weighted imaging revealed clear structural compartmentalization between cranial and caudal components with distinct signal characteristics. Superficial parotidectomy was performed, and histopathology demonstrated PA in the cranial component and WT in the caudal component. The combination of a sharply defined structural boundary and consistent quantitative signal differences suggested biological independence rather than intratumoral variation. Thus, we suggest that qualitative and quantitative MRI assessment may provide useful preoperative clues for identifying histologically distinct synchronous tumors, even when the lesion appears morphologically unified.