We present a rare case of an intra-articular synovial lipoma, which was diagnosed in a patient after a knee trauma. MRI is the imaging modality of choice to suggest the diagnosis preoperatively, by demonstrating a well-delineated fatcontaining lesion. The differential diagnosis of an intra-articular lipomatous lesion consists of lipoma arborescens and synovial lipoma

Declercq, Hugo

Natens, P

Poorteman, Lien

Vanhoenacker, Filip

Wetzels, K

L Poorteman

H Declercq

P Natens

K Wetzels

F Vanhoenacker

Crossref

BJR|case reports

Intra-articular synovial lipoma of the knee joint

We present a rare case of an intra-articular synovial lipoma, which was diagnosed in a patient after a knee trauma. MRI is the imaging modality of choice to suggest the diagnosis preoperatively, by demonstrating a well-delineated fat-containing lesion. The differential diagnosis of an intra-articular lipomatous lesion consists of lipoma arborescens and synovial lipoma

Directory of Open Access Journals

Ghent University Academic Bibliography

Received:9 February 2015Revised:10 April 2015Accepted:16 April 2015Cite this article as:Poorteman L, Declercq H, Natens P, Wetzels K, Vanhoenacker F. Intra-articular synovial lipoma of the knee joint. BJR Case Rep2015;1:20150061.CASE REPORTIntra-articular synovial lipoma of the knee joint1L POORTEMAN, MD, 1H DECLERCQ, MD, 2P NATENS, MD, 3K WETZELS, MD and 4F VANHOENACKER, PhD, MD1Department of Radiology, AZ Sint Blasius, Dendermonde, KU Leuven, Belgium2Department of Orthopedics, AZ Sint Blasius, Dendermonde, Belgium3Department of Pathology, AZ Sint Blasius, Dendermonde, Belgium4Department of Radiology, AZ Sint-Maarten, Duffel-Mechelen, University Hospital Antwerp, University of Ghent, BelgiumAddress correspondence to: Dr Lien PoortemanE-mail: lien.poorteman@gmail.comABSTRACTWe present a rare case of an intra-articular synovial lipoma, which was diagnosed in a patient after a knee trauma. MRI isthe imaging modality of choice to suggest the diagnosis preoperatively, by demonstrating a well-delineated fat-containing lesion. The differential diagnosis of an intra-articular lipomatous lesion consists of lipoma arborescens andsynovial lipoma.CLINICAL PRESENTATIONA 72-year-old female presented to the orthopaedic surgeonafter a bike accident. There was joint effusion and painover the medial but mostly the lateral joint space of theright knee. No masses were palpable. Further medical his-tory of the patient was unremarkable.INVESTIGATIONS AND IMAGING FINDINGSRadiographs were initially interpreted as normal(Figure 1). Retrospectively, a subtle low-density structureadjacent to the lateral joint space can be seen, suggestiveof a fat-containing lesion. There were no soft tissue calci-fications. MRI showed a tear on the body and posteriorhorn of the medial meniscus. In addition, a well-circum-scribed soft-tissue lesion with fatty consistency was seenunderneath the lateral collateral ligament and the popli-teus tendon. The mass was slightly inhomogeneous, withsome subtle intralesional foci of intermediate signal inten-sity on T1 weighted images and high signal intensity onT2 weighted images (Figure 2).DIFFERENTIAL DIAGNOSISThe diagnosis of an intra-articular lipomatous lesion wasmade based on these imaging features. Although there isan extensive range of intra-articular masses (Table 1),1 thedifferential diagnosis in our case could be limited to fat-containing lesions. Our preferential imaging diagnosis wassynovial lipoma. Because the patient’s complaints and painwere predominantly located at the lateral joint space, thelesion could be considered as the main cause of her kneepain. No biopsy was performed preoperatively.TREATMENTArthroscopy confirmed a medial meniscus tear as well asa well-delineated synovial-based mass at the lateral jointrecess. The white to yellowish aspect of the mass wasindicative of a lesion of fatty consistency. There was sub-tle vascular engorgement on the surface of the lesion(Figure 3). The mass was excised and the resected speci-men was referred for histopathological examination.OUTCOME AND FOLLOW-UPHistopathological examination revealed normal fibroadi-pose and synovial tissue (Figure 4), which confirmed thediagnosis of a synovial lipoma.The post-operative course was uneventful and the patientleft the hospital after 2 days.DISCUSSIONFat-containing intra-articular soft-tissue masses are rareand include lipoma arborescens and the even more raresynovial lipoma. Although lipomas are common benignneoplasms that occur almost anywhere in the body,intra-articular occurrence is very rare.2 An intra-articu-lar lipoma is a solitary lipomatous lesion with a thinfibrous capsule and a vascular pedicle, often covered bysynovial tissue. Since the first case report in 1979,3 wefound only 21 case reports in the Anglo-Saxon litera-ture describing this type of lipoma, of which almost allare located in the knee joint (18 cases),3–20 1 in the hipjoint,21 1 in the lumbar spine22 and 1 in the tarsometa-tarsal joint.23 One of these reports14 describes the lesionat the lateral recess of the knee joint, very similar toBJR|case reports doi: 10.1259/bjrcr.20150061© 2015 The Authors. Published by the British Institute of Radiology. This is an open access article under the terms of the Creative Commons Attribution4.0 International License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source arecredited.the location in our patient. A synovial lipoma is supposed tooriginate within the joint, either by penetrating the synovialmembrane or by fatty overgrowth from the intra-articularsynovial tissue. It can cause locking of the knee when thelipoma gets impinged between the articular surfaces, withinthe intercondylar notch or upon the meniscus, or it caneven get strangulated if it twists around its stalk, causingsudden knee pain.14 It has been suggested that a synoviallipoma occurs de novo, unrelated to trauma.13 We postulatethat, in our case, the mass was pre-existent, but could havebecome inflamed owing to trauma, resulting in pain at thelateral joint space. The signal intensity of the lesion is simi-lar to fat on all MRI sequences. On radiographs, a low-den-sity structure may be present.13 Treatment of small lesionsconsists of arthroscopic resection, but larger lesions mayrequire resection by open surgery.13The most important differential diagnosis of a synovial lipomais lipoma arborescens. This condition is caused by villous syno-vial proliferation with hyperplasia of the subsynovial adiposetissue.1 The exact aetiology is unknown, but unusual responseto chronic synovial irritation or trauma have been suggested aspossible causes leading to this condition. It most commonlyoccurs in the suprapatellar bursa of the knee joint and causes aFigure 1. Anteroposterior radiograph of the right knee shows asubtle low-density structure adjacent to the lateral joint space,suggestive of a fat-containing lesion (arrow).Figure 2. MRI images of the right knee. (a) T1 weighted coronal image showing a lipomatous mass in the lateral compartment of theknee joint, located between the lateral collateral ligament and the popliteus tendon (black arrow). (b,c) Fat suppressed T2 weightedcoronal and axial image showing the lipomatousmass (largewhite arrows)with subtle signs of inflammation (small white arrow in b).(a) (b) (c)Table 1. Classification of intra-articular masses. Adapted fromSheldon et al1Intra-articular massesNon-infectious synovial proliferative processes▪ Lipoma arborescens▪ Synovial lipoma▪ Synovial osteochondromatosis▪ Pigmented villonodular synovitis▪ Rheumatoid arthritisInfectious granulomatous diseases▪ Tuberculous arthritis▪ Coccidioidomycosis arthritisDeposition diseases▪ Gout▪ Amyloid arthropathyMalignancies▪ Synovial chondrosarcoma▪ Synovial metastasesVascular malformations▪ Arteriovenous malformationsVascular tumours▪ Synovial haemangiomaMiscellaneous conditions▪ Cyclops lesionBJR|case reports L Poorteman et al2 of 4 birpublications.org/bjrcr BJR Case Rep;1:20150061painless, slowly progressive swelling of the joint with recurrenteffusions. As in synovial lipoma, this lesion has a fatty densityon radiographs.1,2 On ultrasound, a hyperechoic frond-likemass can be seen with wave-like motion within the intra-artic-ular effusion.1 MRI investigation shows synovial masses withsignal intensity similar to fat on all pulse sequences.1,2 Micro-scopically, the histological characteristics of the lipoma arbor-escens are similar to synovial lipoma. The differential diagnosisis mainly made based on the macroscopic appearance.14 Thetreatment consists of synovectomy,1,2 with a low recurrencerate.1Other lesions involving the synovium of articulations are listedin Table 1,1 but further discussion of these rare lesions is beyondthe scope of this report.LEARNING POINTS1. Synovial lipoma is a rare intra-articular lesion.2. The lesion is usually located within the knee joint.3. MRI is the preferred imaging technique for diagnosis.4. The most significant differential diagnosis is lipomaarborescens, which has a different macroscopicappearance.5. Treatment consists of (arthroscopic) resection.REFERENCES1. Sheldon PJ, Forrester DM, Learch TJ.Imaging of intraarticular masses.Radiographics 2005; 25: 105–19. doi: 10.1148/rg.2510450502. Stoller DW, Tirman PFJ, Bredella MA,Beltran S, Branstetter RM, Blease SCP.Diagnostic imaging orthopaedics. Salt LakeCity, UT: Amirsys; 2004.3. Pudlowski RM, Gilula LA, Kyriakos M.Intraarticular lipoma with osseousmetaplasia: radiographic-pathologiccorrelation. AJR Am J Roentgenol 1979; 132:471–3. doi: 10.2214/ajr.132.3.4714. Hill JA, Martin WR 3rd, Milgram JW.Unusual arthroscopic knee lesions: casereport of an intra-articular lipoma. J NatlMed Assoc 1993; 85: 697–9.5. Bernstein AD, Jazrawi LM, Rose DJ.Arthroscopic treatment of an intra-articularlipoma of the knee joint. Arthroscopy 2001;17: 539–41. doi: 10.1053/jars.2001.224146. Lee F, Keel SB, Gebhardt MC, Rosenthal DI.Intra-articular lipoma with osteochondroidmetaplasia in the knee joint. Skeletal Radiol2001; 30: 230–3. doi: 10.1007/s0025601003397. Matsumoto K, Okabe H, Ishizawa M,Hiraoka S. Intra-articular lipoma of the kneejoint. A case report. J Bone Joint Surg Am2001; 83-A: 101–5.8. Marui T, Yamamoto T, Kimura T, Akisue T,Nagira K, Nakatani T, et al. A true intra-articular lipoma of the knee in a girl.Arthroscopy 2002; 18: 1–4. doi: 10.1053/jars.2002.319619. Yamaguchi S, Yamamoto T, Matsushima S,Yoshiya S, Matsubara N, Matsumoto T.Solitary intraarticular lipoma causingsudden locking of the knee:a case report and review of the literature.2003; 31: 297–9.10. Yeomans NP, Robertson A, Calder SJ.Torsion of an intra-articular lipoma as acause of pseudo locking of the knee.Arthroscopy 2003; 19: E27. doi: 10.1053/jars.2003.5007811. Kidwai AS, Klassen C, Hemphill S,Griffiths HJ. Radiologic case study. Intra-articular synovial lipoma. Orthopedics 2005;28: 611–13.12. Motsis E, Vasiliadis HS, Xenakis TA.Intraarticular synovial lipoma of the kneelocated in the intercondylar notch, betweenACL and PCL: a case report and review ofthe literature. Knee Surg Sports TraumatolArthrosc 2005; 13: 683–8. doi: 10.1007/s00167-004-0600-yFigure 3. Arthroscopic image showing the intra-articular,smooth-bordered lipomatous mass in the lateral recess of theknee joint.Figure 4. Microphotograph of the obtained sample showingthe presence of normal fat cells and surrounding connectivetissue (a) and feeding arterial vessels (b), together with normalsynovial-lining cells (c). The synovium looks detached fromthe underlying fat cells owing to the preparation of the histo-logical sample.Case report: Intra-articular synovial lipoma of the knee joint BJR|case reports3 of 4 birpublications.org/bjrcr BJR Case Rep;1:2015006113. Yilmaz E, Karakurt L, Akpolat N,Ozdemir Hüseyin, Belhan O, Incesu M.Intra-articular lipoma of the knee joint in agirl. Arthroscopy 2005; 21: 98–102. doi: 10.1016/j.arthro.2004.09.00414. Hirano K, Deguchi M, Kanamono T. Intra-articular synovial lipoma of the knee joint(located in the lateral recess):a case report and review of the literature. TheKnee 2007; 14: 63–7. doi: 10.1016/j.knee.2006.10.00815. Bennani L, Amine B, Aktaou S, Hajjaj-Hassouni N. True intra-articular lipoma in arheumatoid knee. Presse Med 2008; 37:610–13. doi: 10.1016/j.lpm.2007.08.01716. Tudisco C, Farsetti P, Febo A. Solitary intra-articular lipoma locking the knee in a youngboy. J Pediatr Orthop B 2008; 17: 131–3. doi:10.1097/bpb.0b013e3280e12a8317. Min KD, Yoo JH, Song HS, Lee BI. A case ofintra-articular synovial lipoma of the kneejoint causing patellar dislocation. Knee SurgSports Traumatol Arthrosc 2010; 18: 1094–7.doi: 10.1007/s00167-009-1005-818. Zhu W, WangW, Chen Y, Xiao T. Synoviallipoma in intra-patellar fat pad of the kneejoint. Pak J Med Sci 2012; 28: 228–30.19. Hsu J-H, Wu F-Z. Orthopaedic case of themonth: a painless right knee mass in a 55-year-old woman. diagnosis: intraarticularlipoma. Clin Orthop Relat Res 2013; 471:1100–4. doi: 10.1007/s11999-012-2650-720. S Amarjit K, Budhiraja S,Chandramouleeswari K, Anita S. Kneelocking in osteoarthritis due to synoviallipoma: a case report. J Clin Diagn Res 2013;7: 1708–9.21. Margheritini F, Villar RN, Rees D.Intra-articular lipoma of the hip.a case report. Int Orthop 1998;22: 328–9.22. Husson JL, Chales G, Lancien G,Pawlotsky Y, Masse A. True intra-articularlipoma of the lumbar spine.Spine 1987; 12: 820–2. doi: 10.1097/00007632-198710000-0002123. Pavithra P, Arundhathi S,Kodandaswamy CR. Intra articular synoviallipoma of the right tarsometatarsal joint—arare case report. J Clin Diagn Res 2004; 8:FD03–FD04.BJR|case reports L Poorteman et al4 of 4 birpublications.org/bjrcr BJR Case Rep;1:20150061

Abstract: We present a rare case of an intra-articular synovial lipoma, which was diagnosed in a patient after a knee trauma. MRI is the imaging modality of choice to suggest the diagnosis preoperatively, by demonstrating a well-delineated fatcontaining lesion. The differential diagnosis of an intra-articular lipomatous lesion consists of lipoma arborescens and synovial lipoma

Intra-articular synovial lipoma of the knee joint

Abstract

Similar works

Full text

Available Versions

Crossref

Directory of Open Access Journals

Ghent University Academic Bibliography

Institutional Repository Universiteit Antwerpen