Spindle Cell Sarcoma of the Abdominal Aorta Following Endovascular Aneurysm Repair in a Kidney Transplant Recipient

A kidney transplant recipient developed spindle cell sarcoma within an abdominal aortic aneurysm following prior endovascular aneurysm repair (EVAR). The patient had undergone EVAR for abdominal aortic aneurysm before successful living-donor kidney transplantation and maintained stable graft function under immunosuppressive therapy. Two years after transplantation, he presented with back pain, elevated inflammatory marker, and aneurysm enlargement, initially suspected as an infected aneurysm. Despite antibiotic therapy, the lesion progressed. Positron emission tomography demonstrated increased fluorodeoxyglucose uptake, and computed tomography-guided biopsy revealed undifferentiated spindle cell sarcoma with unclear lineage differentiation. Surgical resection was not feasible, and systemic chemotherapy was initiated; however, disease progression continued, and the patient died 7 months after admission. Aortic sarcoma following EVAR is rare and may mimic infection or inflammatory complications. Clinicians should consider malignant etiologies when transplant recipients with prior EVAR present with atypical aneurysm enlargement or persistent inflammatory findings, and early tissue diagnosis may be necessary.