A rare and potentially fatal cause of popliteal fossa swelling.

Popliteal vein aneurysms (PVAs) represent a rare form of venous aneurysm and necessitate prompt diagnosis and management due to their well-established role as a source of pulmonary emboli. Surgical repair is usually curative; we present the case of a 47-year-old woman with a recurrent PVA presenting as a soft popliteal fossa mass with associated sensory deficit affecting the right foot, 4 years after initial operative repair. Venous duplex imaging demonstrated a saccular aneurysm originating from the posterior wall of the right popliteal vein. In light of the long-term risk of potentially life-threatening pulmonary embolism, surgical repair was undertaken by tangential aneurysmectomy and long saphenous vein patch venoplasty. This case emphasises the importance of including PVA in the differential diagnosis of popliteal fossa swellings as well as the need for long-term follow-up to detect late recurrence with subsequent avoidance of the otherwise significant potential morbidity and mortality.