PIGMENTED VILLONODULAR SYNOVITIS (PVNS)
- Pigmented villonodular synovitis (PVNS) is a slow growing lesion of uncertain etiology arising from the synovial membrane, characterized by villous and nodular overgrowths of the synovial membrane of the bursa or the tendon sheath.
- The appendicular skeleton, especially large joints such as the knee and hip joints are frequently involved.
- Synonyms: Until Jaffe in 1941 proposed the term pigmented villonodular synovitis this condition has been known as synovial xanthoma, synovial endothelioma/ fibroendothelioma, Benign fibrous histiocytoma, xanthomatous GCT, Myeloplaxoma, fibrohemosideric sarcoma.
• Sex: no sex based predilection
• Age: 3rd-4th decades of life, rare in children
• Incidence: 1.8 per million population
• Repetitive trauma (50%) causing recurrent local hemorrhage to affected joint (cf:hemophilics show progressive erosive arthropathies).
• Proliferation of the synovium of joints, tendon sheaths or bursae.
• It is a reactive condition, and not a true neoplasm.
• PVNS classically presents as a monoarticular disease, mimicking arthritis.
• Recurrent atraumatic haemarthrosis is a characteristic feature.
Monoarticular involvement (most common), occurs in two forms: localized and diffuse.
Two variants as described by Granowitz -
- Localized form (LPVNS): focal involvement of the synovium
- Nodular / Sessile or Pedunculated masses.
- Hands & feet
- b. Diffuse form (DPVNS) (more common): affects virtually the entire synovium, eg.
- Intra-articular PVNS tends to be of the diffuse form.
- Tendon sheath PVNS (Giant cell tumour of tendon sheath[GCCTS]), the nodular form
• MC site: knee joint, followed by the hip and shoulder.
- anterior compartment common
- mostly at meniscocapsular junction
- synovium in the region of the anterior horn of the medial meniscus is the most common site
- infrapatellar fat pad, suprapatellar pouch, intercondylar notch, anterior horn of the lateral meniscus, and the medial and lateral recesses of the knee have been reported.
• Uncommon : elbow, ankle, shoulder, foot, wrist
o Reduced range of movement
o Instability/palpable mass
Aspiration of joint: characteristically reveals a blood tinged brownish-stained aspirate.
• Soft tissue swelling will be marked due to haemorrhage and lobulated synovial tissue.
• May reveal cysts or erosions in the joint mimicking gout.
• Bony erosions are usually from without, especially in the hip
• Periarticular erosions, with a thin rim of reactive bone
• Late feature of joint space narrowing indicates articular cartilage loss, is difficult to distinguish from primary OA
• Ideal investigation
• Nodular mass (periarticular or synovial) with bone erosion
• Loculated joint effusions, Complex heterogeneous echogenic masses and markedly thickened synovium
• Direct visualisation of synovium
• Has both diagnostic and therapeutic value in resection of tumours
• LPVNS is pedunculated, lobular lesion localized to one area of the synovium.
• On microscopy, Histiocytes, lipid laden macrophages, hemosiderin containing cells and frequent giant cells are seen
o Total synovectomy (open or arthroscopic):
- Open (anterior approach midline incision or medial parapatellar arthrotomy) for the diffuse form for the intraarticular component
- Arthroscopic synovectomy, has gained popularity, has several advantages over the open technique, preferred for LPVNS, shows higher recurrence in DPVNS.
• Radiotherapy (3500- 4000 cGy) (Radiation induced synovectomy/ intra-articular radiation synovectomy using yttrium Y-90) has been used in the management of recurrences with varying success
• LPVNS: excellent prognosis, low recurrence rate if managed surgically, recurrence 8%.
• DPVNS: surgical excision difficult, recurrence rate of up to 46%.