Undifferentiated intimal sarcoma mimicking a mycotic aneurysm

Intimal sarcoma of arteries is a rare malignant tumor, which often mimics other vascular disorders; therefore, preoperative diagnosis is often challenging. We herein report a 71-year-old man who presented with fever and elevated inflammatory markers who had a mass in the left internal iliac artery with rapid growth. Based on clinical findings, a diagnosis of mycotic aneurysm was made. We performed surgical intervention, including resection of the affected vessels with omentopexy, although intraoperative findings were not typical of a mycotic aneurysm. Microscopic and immunohistochemical examination demonstrated undifferentiated intimal sarcoma. The patient died of multiorgan failure two months after the surgery. The vascular surgeon should consider the possibility of a diagnosis of intimal sarcoma for patients with atypical findings and the importance of histological and immunohistochemical examination for precise diagnosis in surgical vascular cases.