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Year : 2003  |  Volume : 13  |  Issue : 4  |  Page : 379-381
Pigmented villo nodular synovitis


Department of Radiodiagnosis, Gokuldas hospital and MY group of hospitals, Indore - 452001, India

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How to cite this article:
Agrawal M, Gupta A, Agrawal A, Singhal M. Pigmented villo nodular synovitis. Indian J Radiol Imaging 2003;13:379-81

How to cite this URL:
Agrawal M, Gupta A, Agrawal A, Singhal M. Pigmented villo nodular synovitis. Indian J Radiol Imaging [serial online] 2003 [cited 2019 Nov 15];13:379-81. Available from: http://www.ijri.org/text.asp?2003/13/4/379/28711

   Introduction Top


Pigmented villonodular synovitis (PVNS) is a rare benign disorder of synovium of unknown etiology. It is characterised by formation of matted masses of villi with hemosiderin deposition in the involved synovial tissue. Because of typical MR imaging findings it is the modality of choice in diagnosing this disorder. Here we report a case of pigmented villonodular synovitis.


   Case report Top


A 36 years male presented with insidious onset of low grade pain and swelling in his left knee joint. The swelling gradually increased over a span of one year. This was associated with limitation of movement in extension and occasional snapping at the left knee joint. There was no preceding history of fever, weight loss, diabetes, tuberculosis, trauma or any intervention at the left knee joint. On examination of knee joints, a diffuse swelling was seen in left knee joint however skin over the swelling was normal and there were no dilated veins. On palpation mild tenderness over the joint was present but local temperature over the swelling was not raised. The movements at the left knee joint was almost normal except for limitation in extension of 15-20 degrees. The right knee joint examination revealed no abnormality.

Plain radiographs of both knee joints in standard AP and lateral views showed lobulated soft tissue opacity extending superiorly into supra-patellar fossa and posteriorly into popliteal fossa at left knee joint [Figure - 1]. Multiple, small nodular areas of increased density of varying sizes scattered randomly were seen in that soft tissue opacity. The joint space was preserved with normal nineralisation of affected joint. No area of sclerosis, bony 'erosion, bony cyst or periosteal reaction was seen at the left knee joint. Right knee joint was within normal limits. Considering the clinical presentation and radiological findings possibility of synovial disorder was thought with differential diagnosis of synovial Chondromatosis, pigmented villonodularsynovitis, long standing inflammatory arthritis, synovial Hemangioma and synovial sarcoma.

To further characterize the lesion and to evaluate the extent of pathology MRI of left knee joint was done. On T2weighted images a heterogeneous soft tissue with dark nodular areas amid intermediate to high signal was seen [Figure - 2],[Figure - 3],[Figure - 4]. The lesion was extending antero-superiorly into supra-patellar fossa, antero-inferiorly into infra-patellar region [Figure - 2],[Figure - 3], postero- superiorly upto lower 1/3rd of femur, and postero-inferiorly into popliteal fossa [Figure - 2],[Figure - 3],[Figure - 4]. On T1-weighted images this lesion showed areas of intermediate signal intensity. No area of bone erosion or extension of mass into the soft tissue planes was noted. Joint space was well preserved. Considering the typical findings on MR imaging diagnosis of pigmented villonodular synovitis was considered and open surgical synovectomy was done. Histopathological examination of the resected mass confirmed diagnosis of pigmented villonodular synovitis.


   Discussion Top


Pigmented villonodular synovitis (PVNS) is a benign disorder of synovium affecting joints, bursae and tendon sheaths. [1],[2],[3] The disease may be mono-articular or poly-articular, the latter being rare. The knee joint is most frequently involved however it has been described to occur at hip, elbow and wrist joints. Reported average annual incidence is 1.8 cases per million population.[2]

The etio-pathogenesis of PVNS is not known but several possibilities have been suggested including (a) autoimmune, (b) a neoplastic process, (c) an inflammatory process, (d) localised abnormal lipid metabolism with secondary inflammatory and traumatic changes,and (e) a reactive response to chronic trauma and repeated hemorrhage.[1],[3],[4]

Pathologically PVNS is characterised by synovial proliferation leading to formation of matted masses of villi with hemosiderin deposition in the involved synovial tissue.

Microscopically it shows xanthoma or foam cells containing hemosiderin pigment.1 It is because of this hemosiderin typical appearance is obtained on MR imaging.

PVNS usually affects adolescents and young adults which manifests clinically as mild to moderate pain, joint swelling with limitation of movements. Occasionally history of limp, stiffness, locking and snapping may be present. On examination swelling is prominent and is out of proportion to patients symptoms, limitation of movements especially in extension and moderate generalized tenderness may be present. About 66% of patients present with bloody joint effusion which contains elevated levels of cholesterol. [1],[2],[3]

Plain radiographs classically reveals a nodular or lobulated synovial swelling at the affected joint. Well defined marginal erosions of subchondral bone with sclerotic margins may suggest diagnosis particularly if lesions are present on both sides of affected joint.[2],[5] Moreover absence of calcification within the swelling, normal bony mineralisation of the affected joint and preservation of the joint space may further help to narrow down the differential diagnosis especially from inflammatory arthritis. [2],[4],[5],[6]

Although CT scan and invasive investigation - arthrography do help but characteristic and typical findings on MR imaging has fairly high specificity. On arthrography multiple filling defects projecting into the distended joint is seen. [2],[3] Masses of PVNS on CT demonstrates high attenuation foci due to the presence of the hemosiderin. Enhancement of mass after intravenous contrast is almost always seen. Moreover CT precisely delineates bone erosion and cyst formation.

MRI features of PVNS are typical because of the presence of hemosiderin. The standard recommended technique for evaluation of PVNS is spin-echo imaging[2]. Hemosiderin due to its ferromagnetic properties causes shortening of both T1 and T2 relaxation times. The dark signal of hemosiderin appears slightly larger and better appreciated on T2-weighted images due to "blooming effect".[2],[4]. On T2-weighted images the intra-articular masses demonstrates a combination of intermediate to high signal areas representing fluid and congested synovium with interspread areas of low signal intensity of hemosiderin.[2],[3],[4] Marrow edema (if any), cortical erosions and extra - articular extension are also well demonstrated on MR imaging. [2],[4]

Various differential diagnosis on imaging are synovial chondromatosis, sclerosing hemangioma, synovial sarcoma, inflammatory arthritis especially rheumatoid, and long standing infective arthritis. Synovial chondromatosis closely simulates PVNS, however opacities in soft tissue are of uniform size which on T2weighted images are of low signal intensity on all pulse sequences. [2],[3],[5],[6] Synovial sarcoma is frequently associated with bone invasion, periosteal reaction and amorphous calicification. Synovial hemangioma characteristically exhibits intermediate signal intensity on T1, and on T2 and fat suppression techniques as high signal associated with serpentine low intensity septa[3]. Septic arthritis demonstrates significant peri-articular osteoporosis and rapid joint space narrowing apart from marginal erosions and joint effusion

The choice of treatment for PVNS depends upon the distribution and thickness of tissue seen on MR imaging. Various treatments includes arthroscopic synovectomy, open surgical synovectomy, radiation synovectomy or combination therapy.[1],[2],[3] MRI being very sensitive in delineation of abnormal tissue has now not only helped in planning management but also reduced the chances of recurrence which otherwise is reported to occur in 50% of cases.[3]


   Conclusion Top


To conclude, although MR imaging has emerged as the single best modality of choice for evaluation of musculoskeletal and joint disorders, it may not be specific in many disorders. However typical and characteristic MRI findings coupled with clinical features PVNS can be diagnosed with a fair degree of specificity. Moreover non-invasive nature of MR imaging and its sensitivity in better delineation of synovial pathology and its extent have changed the evaluation, treatment planning, and follow up of the disorder.

 
   References Top

1.Samuel L Turek, Orthopaedics - Principles and their application, Lippincott - Raven; Edi. IV, Vol I; 453-454.  Back to cited text no. 1    
2.The Radiologic Clinics of North America, Saunders; Mar. 96, Vol.34, No.2; 311-342.  Back to cited text no. 2    
3.Adam Greenspan, Orthopedic Radiology, Lippincott; Edi. 111; 721-733.  Back to cited text no. 3    
4.Thomas H. Berquist, MRI of the musculoskeletal system, Lippincott - Ravens, Edi.lll; 778-779, 910.  Back to cited text no. 4    
5.David Sutton, Textbook of Radiology and Imaging, Churchill Livingstone; Edi.lll, Vol.1; 190-193.  Back to cited text no. 5    
6.Grainger RG, Allison D, Adam A, Diagnostic Radiology, Churchill Livingstone; Edi.IV, Vol.3; 2021, 2028, 2090, 2148.  Back to cited text no. 6    

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Correspondence Address:
M Singhal
Deptt. of Radiodiagnosis, M.G.M Medical college & M.Y hospitals, Indore- 452 001
India
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Source of Support: None, Conflict of Interest: None


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    Figures

  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]



 

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    Introduction
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    Discussion
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    References
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