Localized Pigmented Villonodular Synovitis of the shoulder: a rare presentation of an uncommon pathology

Pigmented Vilonodular Synovitis is a rare clinical entity characterized as a synovial membrane benign tumour, despite possible aggressive presentation with articular destruction. The localized variant is four times less frequent and the shoulder involvement is uncommon. We present the case of a Caucasian 59 year-old patient, who presented with left shoulder pain, of uncharacteristic quality, with local swelling and marked functional limitation of 1 month duration. Shoulder ultrasonography showed subacromial bursitis. An ultrasound-guided aspiration was performed: synovial fluid was citrine-colored and translucid. One month later, the patient maintained swelling, pain and functional impairment of the left shoulder. New shoulder ultrasound revealed exuberant subacromial bursitis, which was again aspirated using ultrasound guidance. The synovial fluid was haematic, without changes in the cell count or biochemical analysis and cultural exams. We performed an injection with 60 mg of hexacetonide triamcinolone. Two months later there was a relapse, with shoulder ultrasonography once more showing subacromial bursitis with extensive synovial membrane proliferation. Shoulder MRI revealed subacromial bursitis involving the anterior, posterior and medial recesses, with deltoid distension, but without tendinous or intra-articular involvement. In the interior of the bursa hypointense images in T2 were observed, suggesting the diagnosis of Pigmented Vilonodular Synovitis. The patient had surgical bursectomy with success and without complications. The histological exam of the operatory piece confirmed the imaging diagnosis. Pigmented Vilonodular Synovitis is uncommon, rarely affecting the shoulder in a localized variant. It is a diagnosis to be considered in shoulder pain, especially if associated with recurrent subacromial bursitis.