Aortic intimal sarcoma with myxoid features may demonstrate low metabolic activity on positron emission tomography (PET) and resemble benign thrombus or myxoma, potentially complicating diagnosis despite recurrent arterial embolization.
In a case report, researchers described a 69-year-old male patient who presented with persistent abdominal pain following laparoscopic cholecystectomy. Computed tomography revealed an intraluminal mass involving the aortic arch and proximal descending thoracic aorta, accompanied by embolic infarctions of the right kidney and spleen. The diagnostic evaluation included fluorodeoxyglucose (FDG)-PET, surgical resection, histopathologic examination, immunohistochemistry, and molecular testing.
The report focused on discrepancies between preoperative imaging, intraoperative assessment, and definitive pathologic diagnosis. The researchers documented recurrent arterial embolization, tumor characteristics, molecular findings, and postoperative outcomes to illustrate the diagnostic challenges and clinical course associated with myxoidintimal sarcoma.
Preoperative FDG-PET demonstrated minimal metabolic uptake, with a maximum standardized uptake value of 3.1, favoring thrombus rather than malignancy. Despite anticoagulant therapy, the patient subsequently developed left popliteal artery occlusion attributed to embolization. Recurrent embolic events prompted surgical intervention after the patient initially deferred the procedure.
During surgery, the mass appeared gelatinous and well-circumscribed, with a stalk attached to the proximal descending thoracic aorta. Its appearance resembled benign myxoma, and intraoperative frozen section analysis supported that preliminary diagnosis. Surgeons performed en bloc resection of the tumor and its attachment, followed by replacement of the affected aortic segment with a prosthetic graft.
Definitive pathologic examination identified intimal sarcoma with myxoid features. Immunohistochemical testing demonstrated positivity for MDM2, CDK4, and FLI-1, with a Ki-67 proliferation index of 50%. Fluorescence in situ hybridization confirmed MDM2 amplification in both the primary aortic tumor and a distally embolized fragment, establishing their clonal relationship. Regional lymph nodes showed no tumor involvement.
Although grossly complete resection was achieved, microscopic margin assessment was not feasible, preventing confirmation of complete tumor clearance. Adjuvant anthracycline-based chemotherapy was recommended, but the patient declined treatment because of concerns about functional status and treatment tolerance. The patient subsequently developed progressive weight loss and ascites suggestive of metastatic disease and died 159 days postsurgery.
High water content and low cellularity of myxoid tumors may contribute to reduced metabolic activity on FDG-PET, potentially leading to misinterpretation as benign thrombus. The gelatinous appearance of these tumors may also resemble benign myxoma during surgical evaluation. They emphasized that recurrent embolic events in patients with intraluminal aortic masses should raise suspicion for malignancy regardless of apparently benign imaging characteristics.
The findings are limited by the single-patient case report design, which cannot establish the frequency of diagnostic misclassification or the accuracy of individual diagnostic tests. The proposed diagnostic approach, including MDM2/CDK4 immunohistochemistry and molecular testing in suspicious aortic masses, requires validation in larger case series. The patient's clinical course did not establish whether earlier diagnosis or additional treatment would have improved survival.
“Clinicians should maintain a high index of suspicion for malignancy in aortic masses with embolic complications,” wrote lead study author SeungjiHyun, of the Department of Thoracic and Cardiovascular Surgery at Asan Medical Center in Korea, and colleagues.
The study authors reported no conflicts of interest.
