Multimodal Imaging in the Diagnosis of Primary Aortic Epithelioid Angiosarcoma.

Primary malignant tumors of the aorta (PMTA) are rare, yet highly aggressive neoplasms associated with poor prognosis. The preoperative diagnosis of these tumors remains challenging, as conventional imaging modalities, including computed tomography (CT) and magnetic resonance imaging (MRI), frequently fail to distinguish PMTA from atherothrombotic lesions. This case highlighted the efficacy of multimodality imaging, particularly F-18 fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT), in diagnosing PMTA, such as aortic intimal angiosarcomas. A 73-year-old male patient presented with a history of intermittent fever and persistently elevated inflammatory markers over a three-month period. Initial CT revealed a pedunculated intraluminal mass within the descending aorta, accompanied by multiple infarctions of the spleen and kidneys. No apparent contrast enhancement of the lesion was observed on CT. MRI demonstrated mildly high-signal intensity on T1- and T2-weighted images, without marked contrast enhancement. Cine MRI indicated tumor margin mobility, suggesting a dynamic lesion, rather than a fixed thrombus. FDG-PET/CT revealed abnormal hypermetabolic activity within the aortic lesion, with a maximum standardized uptake value of 10.8. Moreover, this modality identified distant metastases within the ribs and femoral head. The patient subsequently underwent descending aortic replacement surgery, and histopathological analysis confirmed the diagnosis of an epithelioid angiosarcoma. Despite postoperative chemotherapy, the patient died due to the progression of brain metastases. This case confirmed the essential role of FDG-PET/CT in distinguishing PMTA from atherothrombotic lesions. Due to the poor prognosis and aggressive nature of PMTA, early diagnosis through multimodal imaging is paramount in guiding appropriate clinical management and improving treatment outcomes.