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Pigmented villonodular synovitis (PVNS)
• Is a benign proliferative disorder of uncertain etiology that affects synovial lined joints, bursae, and tendon sheaths .• characterized by inflammation and
overgrowth of the joint lining
Pigmented villonodular synovitis (PVNS)
• It results in various degrees of villous and/or nodular changes in the affected structures.• PVNS lesions are monoarticular or
solitary. Polyarticular disease is uncommon but more likely in children.
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 & feetb. 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
• The diffuse form typically involves the large joints , while the localized form typically occurs around the small joints of the hands and feet
The localized form often appears around tendon sheaths, in which case it is termed giant cell tumor of the tendon sheath. Rarely, the localized form may develop around large joints. The term PVNS generally is used when the condition, in either diffuse or localized form, affects a joint. Imaging plays an important role in the diagnosis, treatment, and follow-up monitoring of the disorder.
Pigmented villonodular synovitis of the knee. Sagittal T1-weighted magnetic resonance imaging scan (MRI) of the knee shows inhomogeneous foci of low signal in the suprapatellar pouch and, posteriorly, just above the femoral condyle.
Pigmented villonodular synovitis of the knee. Plain radiographic findings of the knee apparently are normal except for the curvilinear calcification seen peripherally to the medial femoral condyle
• The etiology of PVNS remains uncertain.• Neoplasia is the presently accepted
underlying etiology. • Evidence supporting this theory is both
empirical and genetic. PVNS has demonstrated the capability of autonomous growth and rare malignant transformation.
Several genetic studies have demonstrated associated cytogenetic aberrations, including rearrangement involving the CSF-1 and COL6a3 genes, as well as association with trisomy 5 and trisomy 7.[2, 3] Not all cases are associated with such genetic anomalies, suggesting a multifactorial etiology for the disease.
Etiopathogenesis:• 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.
Gross description============================================Focal or diffuse; brown-yellow spongy tissue with variable color and firm nodular consistency
• PVNS lesions on histology demonstrate
synovial cell proliferation, xanthomatous cell accumulation, hemosiderin deposition, and the presence of multinucleated giant cells
Epidemiology• PVNS is an uncommon disease.• The prevalence is approximately 9.2 cases of
extra-articular and 1.8 cases of intra-articular disease per 1 million population.
• Localized lesions are more common than diffuse involvement, comprising 77% of total lesions in one review, with a 3.3:1 localized-to-diffuse predominance ratio.
• Diffuse PVNS affects predominantly large joints, with the knee being the most common (66-80%).• The hip, ankle, shoulder, and elbow
follow in descending frequency.
• Diffuse PVNS has nearly equal incidence in male and female patients, while the localized form demonstrates a female-to-male predominance ratio of 1.5-2:1.• Diagnosis is more common between
ages 20 and 50 years, with a median age of 30 years.
• In general, pigmented villonodular synovitis often manifests initially as sudden onset, unexplained joint swelling and pain; the joint swelling is disproportionate to the amount of pain the patient feels at first. Decreased motion and increased pain occur as the disorder progresses as well as locking of the joint.
• The localized form often manifests initially as a painless, slow-growing mass and progresses to the other common symptoms of PVNS. The swelling often feels warm to the touch.
Investigation: Aspiration of joint: characteristically reveals a blood tinged brownish-stained aspirate.
X-ray: • 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
MRI: • Ideal investigation• Nodular mass (periarticular or synovial) with bone erosion
Sonography:• Loculated joint effusions, Complex heterogeneous echogenic masses and markedly thickened synovium
Arthroscopy:• Direct visualisation of synovium• Has both diagnostic and therapeutic value in resection of tumours
Histolopathology:• 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
Differential diagnosisHemophilic arthropathy, synovial hemangioma, synovial chondromatosis, gout, and amyloid arthropathy may all present similarly on MRI.
Treatment and prognosis
• Although a benign condition, PVNS may result in significant morbidity if left untreated. Pain, loss of function, and eventual joint destruction may result. The primary treatment options include surgical resection via synovectomy or radiation therapy.
Treatment:• Synovectomy: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
Prognosis:• LPVNS: excellent prognosis, low recurrence rate if managed surgically, recurrence 8%.• DPVNS: surgical excision difficult, recurrence rate of up to 46%.