We present a case of diffuse and moderately increased 18F-FDG uptake in the entire left lung on 18F-FDG PET without any morphological parenchymal abnormalities in a patient with recent history of esophageal adenocarcinoma treated by minimal invasive surgery and adjuvant chemotherapy. Contrast-enhanced CT revealed a large embolism in the left pulmonary artery with near total occlusion. In the absence of parenchymal lesions, the increased 18F-FDG uptake is most likely an inflammatory response to a recent ischemic insult. This case illustrates that asymmetric lung hypermetabolism in the absence of parenchymal disease can be caused by a central pulmonary embolism.