Intra-articular Genicular Artery Pseudoaneurysm Mimicking Pigmented Villonodular Synovitis: A Case Report.

Pigmented villonodular synovitis (PVNS) is a non-aggressive entity involving the synovium. Magnetic resonance imaging (MRI) is regarded as the preferred imaging modality. MRI can occasionally be deceptive, with many benign conditions having a propensity for repeated bleeding intimately resembling PVNS. We present a case of an intra-articular pseudoaneurysm of the knee joint resembling PVNS on MRI. This 80-year-old male had multiple comorbidities, including a ruptured abdominal aortic aneurysm presented with recurrent knee swelling. The MRI showed complex hemorrhagic knee joint effusion with an intra-articular arterial branch pseudoaneurysm. The diagnosis was verified by CT angiography.