Inflammatory pseudotumor (IPT) is a rare type of benign mass that mimics neoplastic processes. They are most commonly found in the lung; however, have been described to occur less commonly in nearly all organ systems, including the heart. Cardiac IPTs are exceedingly rare, and account for less than 5% of all extra-pulmonary IPTs [1] and are described in the literature mainly as individual case reports or small case series. There is a pediatric predominance for all IPTs, including cardiac. Cardiac IPTs are usually discovered by echocardiogram and patients undergo further tissue characterization by cardiac magnetic resonance (CMR) imaging. Descriptions of the CMR features of cardiac IPT are present but sparse in the radiology literature. Our case is unique in that it describes a rare presentation of pediatric cardiac IPT as fever of unknown origin with marked systemic inflammation. Further, our case demonstrates the utility of F-fluorodeoxyglucose (FDG) positron emission tomography (PET) as an adjunct noninvasive imaging method in the diagnosis of cardiac IPT.