Review Question - QID 3034

The MRI and biopsy are diagnostic for pigmented villonodular synovitis (PVNS), a tumor like condition that is locally aggressive but without risk for metastatic spread. The MRI demonstrates an intra-articular mass without bone destruction. The biopsy shows a nodular pattern of giant cells, diffuse proliferation of mononuclear cells of synovial- or histiocytic-type, and hemosiderin. These components of the biopsy make the diagnosis of PVNS. Treatment is complete excision (synovectomy) of the lesion.

Bickels et al describe their experience with 7 patients with PVNS and the success of adjuvant therapy. They found a high rate of complications following intra-articular injection of yttrium 90 in the ankle joint. As such, they do not recommend this treatment and like many continue to support synovectomy for symptomatic lesions.

Sharma et al describe 14 cases of PVNS of the foot and ankle evaluating the clinical, radiographic, and histopathology factors which influence local recurrence. They found a 14.3% recurrence rate with standard therapy including amputation for appropriate cases and more importantly identified incomplete synovectomy as a possible contributor towards local recurrence.

Incorrect answers:
1) Aneurysmal bone cyst - this lesion is extra-osseous. ABCs occur within the bone.
2) Periosteal osteosarcoma - the pathological section shows no signs of osteoid or malignant cells
3) Chondroblastoma - again, this lesion is extra-osseous. Chondroblastoma occurs within the bone.
4) Myositis ossificans - typically doesn't occur this close to the joint and would appear different on pathological section.