Contained Rupture of a Thoracic Aortic Aneurysm Mimicking a Malignant Tumor: a Case Report.

An 81-year-old man underwent F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to evaluate a mediastinal mass, which was discovered during the investigation for hemoptysis. The periphery of the mass abutting the aortic arch demonstrated heterogeneously increased FDG uptake, whereas most of the central portion of the mass was photopenic. The mass turned out to be an atheromatous organizing hematoma associated with contained aortic rupture.