PIGMENTED VILLONODULAR SYNOVITIS: MAGNETIC RESONANCE IMAGING APPEARENCE

1. MUSCULOSKELETAL : MK 14 PIGMENTED VILLONODULAR SYNOVITIS: MAGNETICRESONANCE IMAGING APPEARENCE A.B Abdallah, K.Mrad Dali, F.Bouzayène, K.Kadri, N.Mama, M.BenMaitigue*, K.Tlili Radiology service, Sahloul Hospital *Orthopaedic surgery service, Sahloul Hospital MK14

2. INTRODUCTION • Pigmentedvillonodularsynovitis (PVNS) is a rare benign proliferative disorder primarily occurring in the large joints of the appendicular skeleton such as the knee and hip joints. • PVNS is potentially aggressive lesion that attacks the synovium of joints, tendon sheaths or bursae • Diagnosis is made on clinical features, aspiration of the joint, radiographic features and magnetic resonance imaging (MRI), which is the most useful.

3. OBJECTIVES • To evaluate the magnetic resonance (MR) imaging of pigmented villonodularsynovitis (PVNS) of the big joints.

4. MATERIALS AND METHODS • A retrospective review of MR imaging of big joints was performed in 12 patients with clinical and histologically confirmed PVNS • PVNS was diagnosed by synovectomy in 7 cases and arthroscopy in 5 cases.

5. RESULTS • There were 5 males and 7 females • A meanage of 33yearsat diagnosis • All lesions presented as a solitary intraarticular mass • In 9 cases, the disease was located in the knee • It involved the ankle in 2 cases and the hip in 1case. • Clinical symptoms varied gratly (table) • Radiographs revealed a normal appearance in 6 cases, a focal soft tissue mass in 5 cases, bone erosions in 1 case.

6. Reuslts • Articularultrasonagraphyshowed heterogenousechogenic masses in 2 cases and a markedly nodular thickened hypoechoicsynovium in 2 cases • MRI showed in all cases a joint effusion and nodular thickened synovial membrane with prominent T1 low signal intensity, variable T2 signal intensity and “blooming” artifact from hemosiderin (seen with gradient-echo sequences).

8. Case1: A 19 yearsold girl with pain aindswelling right knee a T1 T2 DP FATSAT Radiography(a) is normal MRI: -joint effusion (*) - synovial thickening prominent in the anterior portion of the joint (arrows) DP FATSAT

9. Case 1 c T2* b a T1+C T2 FATSAT *Mild blooming artifactis seen on the gradient-echo image (a,c) (arrowheads) *Sagittal T1&T2-weightedpostcontrastshow prominent diffuse enhancement (arrows) and joint effusion (*). d T1+C

10. Case2: A 53years oldwomanwithreccurenthemathrosis and swelling right knee. DP FATSAT T2 STIR MRIreveal a large amount of high-signal-intensity tissue (*) withposterior extension that replaces the entire knee joint. Extrinsicerosions of the femur and tibia with low-signal-intensity margins are also seen (straight arrows). Radiographyshows extensive erosion of the femoral lower extremitywithscleroticmargins (arrows) and maintainedknee joint space.

11. Case 2 T2* T1+C b a (a) The gradient-echo image also shows focal hypointense areas (arrowheads), findingsthatrepresent the blooming artifactfromhemosiderin The tissue mass (*), has prominent diffuse enhancement on axial(b) and sagittal (c)- T1-weightedpostcontrast c T1+C: coronal

12. Case 3: a 19 yearold teenager with a swellingleftknee (a) Lateralradiograph shows an illdefined area of softtissue opacitythat replaces the normal Hoffa fat pad (arrow). a T2 T1 (b)Transverse sonogramof the kneereveals the hypoechoicintraarticularsofttissue mass (arrows) Sagittal T1& T2-weighted: revealan effusion and synovial thickening in the anterior portion of the joint(*) b

13. Case 3 T2* Mild blooming artifactis seen on the gradient-echo image T1 FATSAT+C DP FATSAT Sagittal proton-density–weightedfatsuppressed:There is a thick low-signal-intensity rim with areas of nodularity Sagittal T1-weightedpostcontrastshows prominent diffuse enhancement

14. Cas 4: A 39 yearsoldwomanhad pain and swelling in the anterior aspect of his ankle for four years. T2 a T1 -(a)Lateral radiograph of the ankle shows an anterior soft-tissue mass (curved arrows) -MRI shows a well-definedlocalizedmass in the anterolateral ankle joint (*) which has an intermediate density T1 & T2 signal with prominent diffuse enhancement (arrowheads). T2*

15. Case 4 STIR T1+C T1+C The anterior soft-tissue mass presents amildlyhighSTIR signal withprominent diffuse enhancement (arrowheads) on sagittal and axial sequences.

16. Cas 5: A 19 yearsold girl whopresentsankle pain and swelling. T2 T1 *Lateral radiograph: anterior soft-tissu mass of the ankle joint *This mass presents with an intermediate T1& T2 signal without bone erosion.

17. T2* T1+C STIR The anterior soft-tissue mass presents amildlyhighSTIR signal withprominent diffuse enhancement (*) on sagittal and axial sequences. The gradient-echo image shows focal hypointense areas (arrowheads), thatrepresent the blooming artifactfromhemosiderin . T1+C

18. DISCUSSION • Pigmented villonodularsynovitis (PVNS) is a slow growing lesion of uncertain etiology arising from the synovial membrane. • It is a disease of synovial membrane characterized by a proliferation of mononuclear cells, probably of histiocytic origin, deep to the synovial lining cells. • It represents a benign, hypertrophic synovial process characterized by villous, nodular, and villonodularproliferation and pigmentation fromhemosiderin of the synovial membrane of the bursa or the tendon sheath.

19. Discussion • Pigmented villonodularsynovitis most commonly affects adult patients in the third of fourth decades of life, in our study 4 patients (33 %) were aged under 22 years • Patients present with joint pain, swelling, and stiffness. • Although any joint may be affected by PVNS, the knee is the most common site, involved in 80% of cases ( 75%) in our study. Other joints frequently involved are the hip, shoulder, and ankle. • These lesions are subclassified as localized or diffuse form.

20. Discussion • Usually only one joint is affected • Becauseclinicalsigns and symptoms are typicallynonspecific and laboratory tests are unremarkable, the radiologistplays a keyrole in the diagnosis and treatment of thispathology.

21. Radiography • Radiographic findings are normal in up to 20% of cases. It was normal in 50% in our study. • Overall, osseousabnormalities are present in 15%–25% of cases • Extrinsicerosion, oftenwithwell-defined sclerotic margins, of the underlying bone is the most common osseous abnormality, seen in 9%–25% of cases. It involves joints withtight capsules, because of pressure phenomenon (foot or ankle).

22. Radiography • Subtle or obviousjuxtaarticularsoft-tissue massesthatappear dense because of highiron content (hemosiderin) in the synovium • Periostealreaction (8% of cases) and calcifications (6%)are rare • Preservation of bonedensity.

23. Sonographicappearances • Sonographicappearances of intraarticular PVNS are nonspecific. • Sonographic features of diffuse intraarticular disease include joint effusion, comple heterogeneous echogenic masses, and markedly thickened hypoechoic synovium that may have nodular and villous projections • Extrinsic erosion of underlying bone may also be seen.

24. Sonography • PVNTS manifests as a hypoechoic solid mass with well-defined margins that is intimately related to the associated involved tendon • Doppler imaging commonly reveals increased blood flow in all types of PVNS.

25. CT • PVNS lesionsmay show highattenuationbecause of the presence of hemosiderin. • It canalsobecaused by chronicbleeding or calcifications. • CT isusefulindelineatingbonecyst formation and erosions. • CT iswellsuited for Imaging guidance of diagnostic coreneedlebiobsy.

26. MR Imaging • MR imaging has become the technique of choicefor diagnosisand follow-up in patients withpigmentedvillonodularsynovitis. • It isuseful for preoperative, non-invasive diagnosis of PVNS in many cases • The appearancedepends on the relative proportions of lipid, hemosiderin, fibrous, stroma, pannus, fluid and cellular elements

27. MR Imaging • The mostcharacteristicfindingisnodularintraarticular masses of low signal intensityon T1 (all patients), T2 (75% in ourstudy) and proton density. • Areas of lowsignal intensity on T2-weighted images are due to the magnetic susceptibility effect produced by hemosiderin and are more manifest in the periphery of the lesions, present in all our cases. • This decreasedsignal intensity is more pronounced on gradient-echo images and at high field strengths.

28. MR Imaging • Gradient-echo images demonstrate an enlargement of the low-signal-intensity areas (“blooming”) that is caused by magnetic susceptibility artifact. • The blooming effect, which specifically signifies the presence of hemosiderin as the cause of low signal intensity, is nearly pathognomonic of PVNS at MR imaging.

29. MR Imaging • Occasionally, intralesional areas of high signal intensity on both pulse sequences may be present. These areas are believed to be due to fat, edema, or inflammation, • PVNS lesionscharacteristically show prominent contrast enhancementwith the administration of gadolinium (90% in ourstudy), • The signal intensity of the lyticsubchondral lesions varies and may indicate the presence of fluid, soft tissue, or hemosiderin.

30. Treatment • Treatment of PVNS is required to prevent progressive loss of function and destruction of the involved joint or the tendon or bursa • Treatment options includesurgicalresection, radiation therapy, pharmaceuticalmodulation of the disease, or a combination of theseapproaches • Synovectomy may be performed with either an arthroscopic or open arthrotomy technique • The recurrence rate for localized disease is generally lower (from0% to 44% )than that for diffuse intraarticularPVNS (8% to 56%).

31. Conclusion • PVNS represents an uncommon benign hyperthrophic synovial process • It is characterized by villous, nodular, and villonodular proliferation and pigmentation from hemosiderin • The MR imaging is useful for diagnosis and is optimal for identifying the extent of synovial disease, surveying and detecting reccurence.