Year : 2005 | Volume
: 15 | Issue : 4 | Page : 455--458
Pigmented villonodular synovitis of the knee : A case report
S Singh, V Chowdhury
Department of Radiodiagnosis, Maulana Azad Medical College and Associated Lok Nayak Hospital, Jawaharlal Nehru Marg, New Delhi- 110 002, India
212, Sfs Flats, Phase Iv, Ashok Vihar, Delhi - 110052
|How to cite this article:|
Singh S, Chowdhury V. Pigmented villonodular synovitis of the knee : A case report.Indian J Radiol Imaging 2005;15:455-458
|How to cite this URL:|
Singh S, Chowdhury V. Pigmented villonodular synovitis of the knee : A case report. Indian J Radiol Imaging [serial online] 2005 [cited 2020 Apr 7 ];15:455-458
Available from: http://www.ijri.org/text.asp?2005/15/4/455/28772
Pigmented villonodular synovitis (PVNS) is an uncommon benign proliferative disorder of the synovium of unknown cause. The joint most commonly affected is the knee followed by the hips, ankle, shoulder and elbow although any synovial joint may be affected. It is most frequently encountered in the third and fourth decades of life with no significant gender predisposition. Its diagnosis is often delayed because complaints and symptoms are non-specific. Familiarity with the disease may ensure an earlier diagnosis and consequent early onset of therapy.
A 16 year old female presented with swelling in the right knee since six months which was out of proportion to the mild degree of pain and discomfort. No history of trauma or any other significant illness was present. On examination tenderness and joint effusion were present. Routine laboratory investigations were normal. X-ray of the right knee was normal [Figure 1].
MRI of the knee was performed which showed synovial thickening and associated joint effusion as hypointense signal on T1 [Figure 2]a and hyperintense signal on T2 with scattered low signal intensity areas within on T2W images representing haemosiderin deposition [Figure 2]b,c.
Lobulated focal mass representing PVNS tissue was seen posterior to the posterior cruciate ligament as intermediate signal intensity on proton density weighted sequence [Figure 3]a and as low signal on T2W images [Figure 3]b .T1 weighted fat saturated gadolinium enhanced MR image showed intense contrast enhancement corresponding to the PVNS soft tissue lesion and the thickened synovium with central region of less prominent enhancement [Figure 4]a,b.
Biopsy from the synovium, right knee revealed synovial tissue with focal collections of chronic inflammatory cells and histiocytes, few of which contained haemosiderin pigment. There was mild hyperplasia of the synovium with focal layer of fibrin consistent with pigmented villonodular synovitis [Figure 5].
Jaffe, Lichtenstein and Sutro first described the disease process they termed pigmented villonodular synovitis in 1941 . It is a rare disorder that may involve the synovium of joints, bursa or tendon sheaths. The disease is usually monoarticular and may appear as either a localized or diffuse form . Diffuse PVNS usually occurs in adults and is observed in the knee in more than 75% of cases. When the lesion arises from a tendon sheath, it is usually localized and discrete and may be termed giant cell tumour of tendon sheath (GCTTS) . GCTTS differs in location as it is classically extra-articular, located around the tendon sheaths of the hands and usually measures less than 2 cm in size .
Grossly, PVNS has diffuse haemosiderin staining as repetitive trauma to the friable villi causes bleeding, the degradation products of which are eventually phagocytosed by synovial and subsynovial histiocytes resulting in both intra and extracellular haemosiderin deposition. Histology thus reveals synovial hyperplasia, hypervascularity and accumulation of histiocytes. Multinucleated giant cells,, lipid laden macrophages, fibroblasts, intra and extracellular haemosiderin are characteristic features. PVNS, giant cell tumour of the tendon sheath and pigmented villonodular bursitis are histologically identical .
Other conditions causing recurrent haemarthrosis eg. haemophilia, haemochromatois and haemosiderosis also demonstrate haemosiderin on histological examination, however, the pigment is largely confined to the synovial cells and macrophages, whereas the distribution in PVNS is more diffuse. Giant cells and histiocytes seen in PVNS are not features of these other conditions.
Symptoms are usually non-specific e.g. pain, warmth and swelling and on examination tenderness and effusion are present. Joint mobility commonly becomes restricted as the lesion expands. Joint aspiration yields xanthochromic or serosanguineous fluid, however, the lack of bloody effusion does not exclude the diagnosis of PVNS .
Radiographic studies show subtle or obvious juxtaarticular soft tissue masses that appear dense because of high iron content (haemosiderin) in the synovium. Erosive changes in the underlying bone occur in upto 50% of cases, most commonly in joints with tight capsules such as hips or elbows because of a pressure phenomenon . 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. Preservation of bone density is another consistent feature. The relative lack of productive bone formation helps to differentiate PVNS from osteoarthritis. Radiographically visible calcifications are rare in PVNS. If calcifications are present, another diagnosis such as synovial osteochondromatosis should be considered .
CT scans show the PVNS lesions as high attenuation because of the haemosiderin content. CT is useful in delineating bone cyst formation and erosions. CT is well suited for image guidance of diagnostic core needle biopsy.
MRI is the current imaging technique of choice . Although the MR findings in PVNS are not pathognomonic, they are highly suggestive of the diagnosis. The MRI features of PVNS depend on the fat, fibrous tissue and iron present. The presence of haemosiderin within tissue causes shortening of both T1 and T2 relaxation times. Haemosiderin has magnetic susceptibility properties. This is manifested as low signal "blooming effect" best appreciated on gradient echo sequences. Areas of high signal on T1 sequences represent either lipid laden macrophages or haemorrhage. Areas of bright signal on T2 weighted images may be present within the abnormal synovial membrane and are believed to represent loculated areas of joint fluid trapped within the synovial membrane. The lesions of PVNS show intense enhancement after administration of gadolinium . Options for treatment include surgical synovectomy, arthroscopic synovectomy, radiation synovectomy and combined procedures.
MRI plays an important role in determining the best treatment approach by providing information about the distribution and thickness of PVNS tissue. Imaging must include the entire joint and adjacent soft tissues and a specific note should be made as to the exact location of all abnormal tissue for instance, the presence of large amount of synovial tissue posterior to the cruciate ligaments may indicate the need for posterior and anterior synovectomy because the tissue cannot be removed with an anterior approach. After treatment, some inflammatory tissue may be seen within the joint, this inflammation usually subsides on follow up studies. Recurrent disease usually has the same signal characteristics as the original process .
|1||Jaffe HL, Litchtenstein L, Sutro C. Pigmented villonodular synovitis: bursitis and tenosynovitis. Arch Pathol 1941; 31: 731-765.|
|2||Bravo SM, Winalski CS, Weissman BN. Pigmented villonodular synovitis. Radiol Clin North Am 1996; 34: 311-326.|
|3||Wong K, Sallomi D, Janzen DL, Munk PL, O'Connell JX, Lee MJ. Monoarticular synovial lesions : radiologic pictorial essay with pathologic illustration. Clin Radiol 1999; 54:273-284.|
|4||Dorwart RH, Genant HK, Johnston WH, Morris JM. Pigmented villonodular synovitis of synovial joints : Clinical, pathologic and radiologic features. AJR 1984; 143: 877-885.|
|5||Lin J, Jacobson JA, Jamadar DA, Ellis JH. Pigmented villonodular synovitis and related lesions : the spectrum of Imaging findings. AJR 1999; 172:191-197.|
|6||Al-Nakshabandi NA, Ryan AG, Choudur H et al. Pigmented villonodular synovitis. Clin Radiol 2004; 59:414-420.|
|7||Hughes TH, Sartoris DJ, Schweitzer ME, Resnick DL. Pigmented villonodular synovitis : MRI characteristics. Skeletal Radiol 1995;24:7-12.|
|8||Winalski CS, Foldes K, Gravallese EM, Weissman NM. Synovial membrane disorders. In Stark D, Bradley WG eds Magnetic resonance imaging 3rd ed Mosby 1999: 1079-1095.|