Coexistence of Lung Cancer and Warthin Tumour in a Smoker: Importance of Accurate Interpretation of 18F-FDG-Avid Parotid Lesions.

Warthin tumour is a benign salivary gland neoplasm strongly associated with smoking and known for avid 18F-FDG uptake. We report a 53-year-old male chronic smoker presenting with tinnitus and ear pain. A resected brain mass demonstrated metastatic carcinoma (TTF-1 positive, CK7 diffuse). 18F-FDG PET/CT revealed a moderately 18F-FDG -avid left upper lobe pulmonary nodule and a small 18F-FDG -avid intraparotid lesion. Given the smoking history and imaging characteristics, Warthin tumour was favoured over metastasis. Lung biopsy confirmed moderately to poorly differentiated adenocarcinoma; parotid FNAC confirmed Warthin tumour. This case highlights the diagnostic pitfall of 18F-FDG -avid benign salivary lesions during lung cancer staging.