ABSTRACT
Pigmented villonodular synovitis is a benign neoplastic condition arising from the synovium. The synovium is pigmented (loaded with increased mitochondria siderosomes), metaplatic, pedicled or non-pedicled, and hypertrophied. It commonly arises from mensicocapsular junction. It presents as a localized or diffuse variety. Localized variety presents with locking, effusion, pain, reduced range of motion, palpable mass, or pain over the joint line which mimics different pathological conditions. We present a case of localized pigmented villonodular synovitis which led to diagnostic dilemma and mimicked common pathological conditions. Very few case reports are reported in which the lesion is only diagnosed with arthroscopy when other imaging and clinical findings are misleading.