Pigmented Villonodular Synovitis is sometimes called PVNS. PVNS is a slow growing, benign, reactive synovial proliferation characterized by proliferation of pigment laden histiocytes and giant cells. The lesion is usually intra-articular, with or without extra-articular extension. If it occurs extra-articular, this is called “giant cell tumor of the tendon sheath”, and this is not related to giant cell tumor of the bone. The lesion is usually intra-articular, with or without extra-articular extension. If it occurs extra-articular, this is called “giant cell tumor of the tendon sheath”, and this is not related to giant cell tumor of the bone. Giant cell tumor of the tendon sheath is a superficial soft tissue small nodule that is painless usually affecting the hand, the wrist, and the feet (occurs extra-articular from the beginning). PVNS is intra-articular. The patient complains of unilateral, spontaneous intermittent pain, swelling, and effusion with decreased range of motion. The patient may complain of recurrent hemorrhagic effusion, so with aspiration of the knee there will be brownish or bloody fluid. It usually occurs predominantly in the knee (about 80%) and this is followed by the hip. You may feel a boggy soft tissue mass in the knee or behind the knee.
With x-rays, the PVNS tumor may infiltrate and erode bone, extending into the soft tissue surrounding the involved joint. When looking at the x-ray, you may find well defined erosions, such as osteolytic changes on both sides of the joint. The PVNS probably is a diffuse, advanced disease. An MRI will show soft tissue masses and effusion due to synovial proliferation. The lesion can be localized or nodular. The physician will find nodular lesions inside the joint, usually the anterior knee. There will be low intensity signal in T1 and in T2 MRI due to hemosiderin deposition. This MRI signal is characteristic of PVNS. You can also see a diffuse process in the MRI, especially if it involves the posterior compartment (anterior and posterior compartments). The PVNS lesion can also extend beyond the joint with erosions of the joint.
Differential diagnosis include Giant Cell Tumor, Synovial Cell Sarcoma, Synovial Chondromatosis, and hemophilia. Giant cell tumor is a primary bone tumor (lesion inside the bone). Synovial cell sarcoma is a soft tissue sarcoma with translocation X; 18. It can occur near the joint and rarely found intraarticular (does not have giant cells). Synovial Chondromatosis occurs due to metaplasia of the cartilage inside the synovium. The patient will complain of knee pain, swelling, and locking. X-rays and MRIs will show multiple calcified loose bodies (rice bodies) inside the joint. Chondroid tissue in synovial tissue. Treatment is complete arthroscopic synovectomy. Hemophilia is usually a bilateral familial disease.
The pathology is a gross appearance. The physician will find a reddish/brownish stained synovium with extensive papillary projections. Microscopic histology will show mononuclear stroma with histiocytes infiltrating the synovium with hemorrhage and hemosedrine pigments (macrophages with giant cells in the field). Treatment will consist of a focal or nodular excision (arthroscopic or open), a diffusion in the form of a total synovectomy (open, arthroscopic, or combined), or a combination. A combined procedure will consist of an anterior arthroscopic as well as a posterior open procedure, which will have a lower recurrence rate. PVNS has a high local recurrence. Sometimes you use radiation of the patient has multiple local recurrence. If the tumor is a giant cell tumor of the tendon sheath (hand, fingers, or feet), a marginal excision should be performed.
