PigmentedVillonodular Synovitis and Related Lesions: The Spectrum of Imaging Findings

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1 Pictorial Essay PigmentedVillonodular Synovitis and Related Lesions: The Spectrum of Imaging Findings John Lin1, Jon A. Jacobson, David A. Jamadar, James H. Ellis P igmented villonodular synovitis (PVNS) is an uncommon benign proliferative disorder of the synovium of unknown causes. PVNS is a monoarticular process and may appear as cither a localized or diffuse form within the joint [1-4]. Patients present with insidious onset of progressive joint swelling and discomfort I 1, 2]. 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 these patients. In this pictorial essay, we review the range of imaging features in histopathologically proven cases of PVNS involving various joints. Radiographic, CT (including CT-guided biopsy), MR imaging, and sonographic findings are illustrated. This report outlines the characteristic findings of each technique. which may allow narrowed differential or specific diagnosis. We also discuss the merits and limitations of sonographic examination, including the use of power Doppler imaging and the usefulness of sonography in the follow-up evaluation of treated lesions. Clinical Features The estimated incidence of PVNS is two cases per I million persons annually. It most often occurs in patients between 20 and 50 years old [2, 41. In decreasing order of frequency, PVNS most commonly affects the knee, hip, ankle, shoulder, and elbow 151- Recurrent swelling is caused by joint effusion, which is often out of proportion to the mild degree of pain and discomfort. In general. no history of related trauma is reported. Aspiration often reveals xanthochromic or serosanguineous joint fluid; however, the lack of bloody effusion does not exclude the diagnosis of PVNS [2. 4]. Giant cell tumor of the tendon sheath (also called localized nodular tenosynovitis) (Fig. 1 ) and pigmented villonodular bursitis are related lesions that generally occur in extraarticular locations [6]. The diffuse form of giant cell tumor of the tendon sheath usually occurs adjacent to large weight-bearing joints and. in most cases, is considered to represent extraarticular extension of PVNS. Histologically, these lesions show synovial hyperplasia, hypervascularity, and accumulation of histiocytes. Multinucleated giant cells, lipid-laden macrophages, fibroblasts. and intra- and extracellular deposition of hemosiderin are characteristic features. PVNS, giant cell tumor of the tendon sheath, and pigmented villonodular bursitis are histopathologically identical I I, 21. Radiography Radiographic studies show subtle or obvious juxtaarticular soft-tissue masses that appear dense because of high iron content (hemosiderin) in the synovium (Fig. 2A). Radiographically visible calcifications are rare in PVNS (2, 41- If calcifications are present, another diagnosis, such as synovial osteochondromatosis, should be considered. Erosive changes in underlying bone occur in up to 50% of cases, most commonly in joints with tight capsules such as hips or elbows, because of a pressure phenomenon [4] (Fig. 3A). These erosions have well-defined sclerotic borders and are typically nonmarginal in location. Joint space is relatively preserved and significant cartilage destruction generally does not occur until late in the disease process (Fig. 4A). Preservation of bone density is another consistent feature. The relative lack of productive bone formation helps to differentiate PVNS from osteoarthritis. CT PVNS lesions may show high attenuation because of the presence of hemosiderin [4J. High-attenuation tissue within the joint can also be caused by hemophilia, chronic bleeding due to another cause, or calcification. Because of the hypervascular nature of PVNS, contrast enhancement is typically present [4]. CT is useful in delineating bone cyst formation and erosions (Figs. 4B and 5A). CT is well suited for imaging guidance of diagnostic core needle biopsy (Fig. 3B). When tissue diagnosis is required, CTguided biopsies can be performed for precise localization and accurate sampling with low Received May 7, 1998; accepted after revision June 24, All authors: Department of Radiology, The University of Michigan Medical Center, 1500 E. Medical Center Dr., TC 2910, Ann Arbor, Ml Address correspondence to J. Lin. AiR 1999;172: X/99/ American Roentgen Ray Society AJR:172, January

2 Lin et al. Fig year-old woman with giant celltumor oftendon sheath in left foot. A, Anteroposterior radiograph of left foot shows irregular osseous radiolucencies with sclerotic margins affecting several adjacent bones at third and fourth tarsal-metatarsal junctions (arrows). Findings are consistent with lobulated erosions. Note that intervening joint spaces are relatively preserved. B and C, Sagittal (B) and axial (C)fast spin-echo short inversion time inversion recovery MR images reveal cloverleaf-shaped high-signal-intensity lesion (arrows) involving cuboid, lateral cuneiform, and bases of third and fourth metatarsals. Erosions caused by this process correspond to A. Note extension of abnormality (arrowheads) along flexor tendons into plantar soft tissues of foot adjacent to metatarsals. D, Coronal proton density-weighted MR image shows large lobulated mass occupying plantar aspect of forefoot in region of flexor digitorum tendons. Lesion extends between third and fourth metatarsal into dorsal aspect of foot, creating palpable mass (arrows). Note overlying marker of vitamin E capsule (asterisk). 192 AJR:172, January 1999

3 Fig year-old man with pigmented villonodular synovitis of knee. A, Lateral radiograph shows subtle soft-tissue masses of increased density (arrows) representing hemosidenn-laden synovium and prominent swelling in region of suprapatellar bursa consistent with large effusion (arrowheads). No osseous erosions or calcifications are identified. B, Sagittal proton density-weighted MR image reveals joint effusion and lobulated low-signal-intensity masses (arrows) in popliteal fossa. Similar low-signalintensity masses (arrowheads) are seen along postenor aspect of suprapatellar bursa. C, Sagittal gradient-recalled echo MR image shows intraarticular, low-signal-intensity, lobulated masses (arrows)to better advantagethan B, especially in suprapatellar bursa, because ofhigh contrast againstjoint effusion. Masses (arrowheads) appear more prominent because magnetic susceptibility caused by hemosidenn deposition is accentuated with this sequence. D, Sagittal Ti-weighted fat-saturated gadolinium-enhanced MR image shows significant contrast enhancement corresponding to soft-tissue lesions and thickened synovium (arrows). Note small irregular central region of less prominent enhancement (arrowheads) relating to region of more concentrated hemosiderin deposition. E, Sagittal sonogram of popliteal fossa reveals nodular mass (arrows) corresponding to lesion seen on B-D. Note heterogeneous increased echogenicity. POST = posterior, ANT = anterior. F,Longitudinal gray-scale image of suprapatellar bursa shows markedly increased flow within hyperplastic synovial soft-tissue components, consistent with hypervascularity. AL = anterolateral, P = posterior. (Fig. 2 continues on next page) AJR:172, January

4 --._ K Fig. 2. (Continued)-19-year-old man with pigmented villonodular synovitis of knee. G, Power Doppler images of suprapatellar bursa shows markedly increased flow within hyperplastic synovial soft-tissue components consistent with hypervascularity. AL = anterolateral, P = posterior. H, Longitudinal (coronal) power Doppler sonogram of lateral recess of knee shows hypervascularity (arrows) predominantly in periphery of synovial capsule. AL = anterolateral, P = posterior. I, Transverse sonogram of anterior distal thigh obtained before intraarticular radiation treatment shows marked synovial thickening and soft-tissue nodularity occupying and expanding suprapatellar bursa (arrows). Note several pockets offluid (asterisks) representing loculated joint effusion. A = anterior, P = posterior. J and K, Sonograms obtained after six courses of intraarticular radiation that correlate with F and I, respectively, show reduction of synovial masses and near complete resolution of joint effusion in suprapatellar bursa (arrows). A = anterior, AL = anterolateral, P = posterior.

5 .- Pigmented Villonodular Synovitis Fig year-old woman with advanced pigmented villonodular synovitis of right hip. A, Anteroposterior radiograph of pelvis shows multiple large erosions (arrows) of right proximal femur and adjacent acetabulum with axial narrowing of joint space. Erosions are extensive, extending to basicervical region. B, Axial CT scan shows multiple erosions with sclerotic margins on both sides of joint. Soft-tissue masses surround joint. Core needle biopsy technique from anterior approach is illustrated. Fig year-old woman with pigmented villonodular synovitis of left hip. A, Anteroposterior radiograph of pelvis shows well-defined rounded subchondral radiolucencies with sclerotic margins on both sides of joint consistent with erosions (arrows). Joint space is relatively preserved. B, CT scan of left hip reveals well-defined erosions with sclerotic margins in both femoral head and acetabulum. Medial wall of acetabulum is markedly thinned. patient morbidity and at less expense than surgical MR biopsy. Imaging MR imaging is useful for preoperative, noninvasive diagnosis of PVNS in many cases. MR findings reflect the histologic composition of the tissues comprising the PVNS lesions f4, Sj. The appearance depends on the relative proportions of lipid, hemosiderin, fibrous stroma, pannus, fluid, and cellular elements. The most characteristic finding is nodular intraarticular masses of low signal intensity on TI -, T2-, and proton density-weighted sequences: the low signal intensity is a result of the presence of hemosiderin deposition (Figs. 2B, SB, 6A, and 6B). The effects of the ferromagnetic properties of hemosiderin are accentuated on T2- weighted sequences, especially gmdient-recalled echo sequences (Figs. 2C and SC), because of differences in magnetic susceptibility between hemosiderin and adjacent tissues (blooming effeet). PVNS lesions characteristically show prominent contrast enhancement with the administration ofgadolinium 151 (Fig. 2D). Little has been written about the appearance of PVNS on short inversion time inversion recovery sequences. In our five cases with short inversion time inversion recovery sequences available, the lesions all showed diffuse increased signal intensity throughout the lesion, despite low signal intensity on T2-weighted images (Figs. lb. IC, and 6C). We speculate that the edema component of the inflammatory synovitis takes precedence over the signal effect of hemosiderin deposition in this extremely water-sensitive sequence. In certain instances, the presence of hemosiderin may actually increase signal intensity when short inversion time inversion recovery is used because the TI relaxation time of hemosiderin differs from that of fat, When an inversion time is selected to null out fat, hemosiderin may contribute to the overall signal intensity of these lesions. AJR:172, January

6 1 i#{149} t Fig year-old woman with pigmented villonodular synovitis of elbow. A, CT scan in coronal oblique plane with elbow flexed 9O shows large scalloped erosions with sclerotic margins involving olecranon and distal humerus both medially and laterally. B, Axial proton density-weighted MR image shows bulky relatively low-signal-intensity soft-tissue masses (arrows) expanding joint capsule and filling coronoid and olecranon fossae. C, Coronal oblique multiplanar gradient-recalled echo MR image of elbow held in 450 flexed position shows large multilobulated soft-tissue masses and associated osseous erosions of olecranon and distal humerus consistent with PVNS. Soft-tissue masses show heterogeneous signal, with low-signal-intensity foci (arrows) likely representing hemosiderin. Fig year-old woman with focal nodular pigmented villonodular synovitis in right knee. A, Axial Ti-weighted MR image shows ovoid 1.5-cm nodule (arrow) exhibiting homogeneous low signal intensity anterior to lateral femoral trochlea. B, Axial T2-weighted MR image at same level as A shows low-signal-intensity ovoid lesion (arrow), which is minimally increased in signal intensity compared with A. C. Sagittalfast spin-echo short inversion time inversion recovery MR image reveals diffuse heterogeneous increased signal intensity within ovoid mass (arrow)just inferior to patella in intraarticular location. 196 AJR:172, January 1999

7 Pigmented Villonodular Synovitis Sonography Information on the sonographic appearance of PVNS is sparse (7, 8]. Sonography shows an intraarticular process that is consistent with a proliferative synovitis. Findings include loculated joint effusion, complex heterogeneous echogenic masses, and markedly thickened synovium (Figs. 2E-2K). Sonography can show osseous erosions when present. Power Doppler imaging typically shows increased flow in the synovial masses (Fig. 2G). A pattern of relatively increased flow in the periphery of the synovial capsule may be present (Fig. 2H). Sonographic findings are nonspecific and may be seen in other causes of synovitis such as rheumatoid arthritis [7]. Intraarticular radiation therapy has been advocated as an effective treatment for PVNS [9, 10]. We have used sonography to evaluate the results of intraarticular radiatioii therapy in a known case of PVNS. A baseline examination was performed before the initiation of therapy. Another sonogram was obtained after the completion of intraarticular radiotherapy and compared with the initial examination. The follow-up study revealed mild reduction in size of the synovial masses with near resolution of previously noted fluid loculations (Figs. 2J and 2K). Mass size and extent ofjoint involvement can be accurately measured and compared temporally between examinations. Although precise diagnosis based solely on the sonographic findings may be difficult, baseline and follow-up imaging is useful in evaluating the response to treatment and the possibility of recurrence after surgical resection. Also, sonographically guided synovial core needle biopsies should be considered as a means of obtaining a histologic diagnosis. Sonography can be an accurate, inexpensive, and expeditious technique for examination and follow-up. References 1. Jaffe HL, Litchtenstein L, Sutro Ci. Pigmented villonodular synovitis, bursitis and tenosynovitis. Arch Pathol 1941;31: Dorwart RH, Genant HK, Johnston WH, Morris JM. Pigmented villonodular synovitis of synovial joints: clinical, pathologic, and radiologic features. AiR 1984;143: Jelinek JS, Kransdorf MJ, Utz JA, et at. Imaging of pigmented villonodular synovitis with emphasis on MR imaging. AiR 1989;152: Bravo SM, Winalski CS, Weissman BN. Pigmented villonodular synovitis. Radial Cliii North Am 1996:34: Hughes TH, Sartoris DJ, Schweitzer ME, Resnick DL. Pigmented villonodular synovitis: M characteristics. Skeletal Radiol 1995 :24: Miller lf, Potter HG, McCormack RR. Benign soft tissue masses of the wrist and hand: MRI appearances. Skeletal Radio! 1994:23: Kaufman RA, Towbin RB, Babcock DS, CraWfOrd AH. Arthrosonography in the diagnosis of pigmented villonodular synovitis.ajr 1982:139: Chiodi E, Morini G. Sinovite villo-nodulare pigmentosa localizzata del tendine del capo lungo del bicipite: studio ecografico. Radio! Med 1996:92: Wiss DA. Recurrent villonodular synovitis of the knee: successful treatment with yttrium-90. C!in Orthop 1982:169: Chen DY, Lan JL, Chou Si. Treatment of pigmented villonodular synovitis with yttrium-90: changes in immunologic features, Tc-99m uptake measurements, and MR imaging of one case. Clin Rheumato! 1992;l I : AJR:172, January

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