Pigmented villonodular synovitis: Keys to early diagnosis

Pigmented villonodular synovitis is a synovial proliferative disorder that remains a diagnostic difficulty. Many clues in the history, physical examin ation, and radiographic studies can aid in the diagnosis. A patient in the third or fourth decade of life often will present with vague monoarticular complaints. Symptoms include intermittent, extreme deep pain localized to t he hip, occasionally relieved by position. Decreased active and passive ran ge of motion may be found. Small erosions in the head of the femur and acet abulum may occur early in the course of the disease. Magnetic resonance ima ging is the imaging modality of choice and will show the characteristic fin dings of a joint effusion, synovial proliferation, and bulging of the hip. The synovial lining has a low signal on T1- and T2-weighted images, seconda ry to hemosiderin deposition. Pigmented villonodular synovitis should be in cluded in the differential diagnosis of young patients with unexplained hip pain.