Aortic intimal sarcoma mimicking thrombus and benign myxoma: a case report

Intimal sarcoma of the aorta is an extremely rare malignancy characterized by its intimal origin and poor prognosis. The myxoid variant poses significant diagnostic challenges due to its benign-appearing gross morphology and low FDG-PET uptake that can mimic cardiac myxoma or organized thrombus. We present a case of aortic intimal sarcoma that was misdiagnosed as thrombus based on imaging findings, highlighting the diagnostic pitfalls of this rare entity. A 69-year-old man presented with abdominal pain following cholecystectomy. Computed tomography revealed an intraluminal mass in the proximal descending thoracic aorta with embolic infarctions of the right kidney and spleen. FDG-PET demonstrated minimal uptake, suggesting thrombus rather than malignancy. Following recurrent embolic events including left popliteal artery occlusion, surgical resection was performed. Intraoperatively, the tumor appeared grossly consistent with benign myxoma, and frozen section analysis also returned a preliminary diagnosis of myxoma. However, final pathological examination revealed high-grade intimal sarcoma. Myxoid intimal sarcoma of the aorta can mimic benign pathology on both FDG-PET and gross examination. Clinicians should maintain a high index of suspicion for malignancy in aortic masses with embolic complications. Immunohistochemistry for MDM2/CDK4 should be performed to ensure accurate diagnosis even when imaging and macroscopic findings suggest benign pathology.