Synchronous bronchioloalveolar and squamous cell lung cancer with different 18F-FDG avidity on PET/CT.

We report a case of synchronous multiple primary lung cancer diagnosed by 18F-FDG PET/CT. A 78-year-old man underwent staging FDG PET/CT that demonstrated intense tracer uptake in the primary, and a second lesion with low uptake. Histopathologic evaluation revealed synchronous squamous cell and bronchioloalveolar carcinoma, representing 2 distinct primaries. FDG PET/CT may identify and diagnose synchronous multiple primary lung cancer on the basis of different morphologic and metabolic features of distinct tumor entities. Moreover, pulmonary lesions with low FDG avidity may still represent malignant disease, even in the context of biopsy-proven FDG-avid lung cancer.