A 51-year-old woman with dyspnea on exertion, fever, pleural effusion, and pericardial thickening underwent F-FDG PET/CT, which revealed focal hypermetabolic lesions in the right lung and left breast. The histopathology of the lesions was compatible with infiltration of inflammatory cells. Blood eosinophil counts were elevated, and enzyme-linked immunoassays were positive for antibodies to several parasites. After antiparasite medication, blood eosinophil counts were normalized, and PET/CT demonstrated complete disappearance of abnormal FDG accumulation in the lung and breast.