Mycotic Popliteal Artery Aneurysm With Rapid Enlargement Post-Bypass

Popliteal artery aneurysms (PAAs) are the most common type of peripheral artery aneurysms. Mycotic aneurysms involving the popliteal artery are quite rare and can occur as either a primary de novo infection or a secondary infection from another site. To our knowledge, there are no previous case reports on mycotic PAA in which Staphylococcus epidermidis was the primary etiologic pathogen. We present the case of a 55-year-old male who presented with complaints of lower extremity pain and swelling, malaise, and low-grade temperatures for two weeks and was found to have a PAA. He underwent left femoral-popliteal bypass grafting with expanded polytetrafluoroethylene (ePTFE) graft and ligation of the aneurysm. On postoperative day 10, he experienced acute swelling and pain in his lower extremity with foot drop and was found to have rapid enlargement of his aneurysm sac on imaging. He was returned to the operating room emergently where he underwent aneurysmectomy via a posterior fossa approach. Cultures and gram staining of the aneurysm sac were consistent with Staphylococcus epidermidis. As noted above, this case of mycotic PAA was treated with standard vascular surgical techniques, yet it proceeded to enlarge acutely. PAAs that rapidly expand or rupture after surgical interventions may be a sign of infection.