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

INTRODUCTION Pigmented villonodular synovitis (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.

OBJECTIVES To evaluate the magnetic resonance (MR) imaging of pigmented villonodular synovitis (PVNS) of the big joints.

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.

RESULTS There were 5 males and 7 females A mean age of 33 years at 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.

Reuslts Articular ultrasonagraphy showed heterogenous echogenic masses in 2 cases and a markedly nodular thickened hypoechoic synovium 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).

MRI Patients Sex/age Localisation Clinic Radio-graphy Ultra- sound Thickened synovial Joint effusion bone T1 T2 T2* Gado M/45Y right knee -pain normal - low hemosiderin + F/12Y Right knee -Hemarthrosis -swelling F/53Y -Pain, swelling -hemarthrosis Erosion bone Soft tissu mass high M/22Y -Pain Femoral erosion F/45Y femoral erosion M/53Y Left knee M/19Y nodular thickened hypoechoic synovium F/42Y M/34Y Normal F/39Y right ankle heterogenous echogenic masse F/19Y Right ankle _ F/8Y Right hip

Case1: A 19 years old girl with pain aind swelling right knee DP FATSAT Radiography(a) is normal MRI: -joint effusion (*) - synovial thickening prominent in the anterior portion of the joint (arrows) DP FATSAT

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

Case2: A 53years old woman with reccurent hemathrosis and swelling right knee. DP FATSAT T2 STIR MRI reveal a large amount of high-signal-intensity tissue (*) with posterior extension that replaces the entire knee joint. Extrinsic erosions of the femur and tibia with low-signal-intensity margins are also seen (straight arrows). Radiography shows extensive erosion of the femoral lower extremity with sclerotic margins (arrows) and maintained knee joint space.

Case 2 T2* T1+C b a c T1+C: coronal (a) The gradient-echo image also shows focal hypointense areas (arrowheads), findings that represent the blooming artifact from hemosiderin The tissue mass (*), has prominent diffuse enhancement on axial(b) and sagittal (c)- T1-weighted postcontrast c T1+C: coronal

Case 3: a 19 year old teenager with a swelling left knee (a) Lateral radiograph shows an illdefined area of softtissue opacity that replaces the normal Hoffa fat pad (arrow). a T2 T1 (b)Transverse sonogram of the knee reveals the hypoechoic intraarticular softtissue mass (arrows) Sagittal T1& T2-weighted: reveal an effusion and synovial thickening in the anterior portion of the joint(*) b

Sagittal T1-weighted postcontrast shows prominent diffuse enhancement Case 3 T2* Mild blooming artifact is seen on the gradient-echo image T1 FATSAT+C DP FATSAT Sagittal proton-density–weighted fatsuppressed: There is a thick low-signal-intensity rim with areas of nodularity Sagittal T1-weighted postcontrast shows prominent diffuse enhancement

Cas 4: A 39 years old woman had 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-defined localized mass in the anterolateral ankle joint (*) which has an intermediate density T1 & T2 signal with prominent diffuse enhancement (arrowheads). T2*

Case 4 STIR T1+C T1+C The anterior soft-tissue mass presents a mildly high STIR signal with prominent diffuse enhancement (arrowheads) on sagittal and axial sequences.

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

T2* T1+C STIR The anterior soft-tissue mass presents a mildly high STIR signal with prominent diffuse enhancement (*) on sagittal and axial sequences. The gradient-echo image shows focal hypointense areas (arrowheads), that represent the blooming artifact from hemosiderin . T1+C

DISCUSSION Pigmented villonodular synovitis (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 villonodular proliferation and pigmentation from hemosiderin of the synovial membrane of the bursa or the tendon sheath.

Patients present with joint pain, swelling, and stiffness. Discussion Pigmented villonodular synovitis 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.

Usually only one joint is affected Discussion Usually only one joint is affected Because clinical signs and symptoms are typically nonspecific and laboratory tests are unremarkable, the radiologist plays a key role in the diagnosis and treatment of this pathology.

Radiography Radiographic findings are normal in up to 20% of cases. It was normal in 50% in our study. Overall, osseous abnormalities are present in 15%– 25% of cases Extrinsic erosion, often with well-defined sclerotic margins, of the underlying bone is the most common osseous abnormality, seen in 9%–25% of cases. It involves joints with tight capsules, because of pressure phenomenon (foot or ankle).

Periosteal reaction (8% of cases) and calcifications (6%) are rare Radiography Subtle or obvious juxtaarticular soft-tissue masses that appear dense because of high iron content (hemosiderin) in the synovium Periosteal reaction (8% of cases) and calcifications (6%) are rare Preservation of bone density.

Sonographic appearances Sonographic appearances 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.

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.

CT PVNS lesions may show high attenuation because of the presence of hemosiderin. It can also be caused by chronic bleeding or calcifications. CT is useful indelineating bone cyst formation and erosions. CT is well suited for Imaging guidance of diagnostic core needle biobsy.

MR Imaging MR imaging has become the technique of choice for diagnosis and follow-up in patients with pigmented villonodular synovitis. It is useful for preoperative, non-invasive diagnosis of PVNS in many cases The appearance depends on the relative proportions of lipid, hemosiderin, fibrous, stroma, pannus, fluid and cellular elements

MR Imaging The most characteristic finding is nodular intraarticular masses of low signal intensity on T1 (all patients), T2 (75% in our study) and proton density. Areas of low signal 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 decreased signal intensity is more pronounced on gradient-echo images and at high field strengths.

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.

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 lesions characteristically show prominent contrast enhancement with the administration of gadolinium (90% in our study), The signal intensity of the lytic subchondral lesions varies and may indicate the presence of fluid, soft tissue, or hemosiderin.

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 include surgical resection, radiation therapy, pharmaceutical modulation of the disease, or a combination of these approaches Synovectomy may be performed with either an arthroscopic or open arthrotomy technique The recurrence rate for localized disease is generally lower (from 0% to 44% )than that for diffuse intraarticular PVNS (8% to 56%).

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.