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Pigmented villonodular synovitis of the knee in a 9-year-old child.

Abstract: This report describes a 9-year-old girl with pigmented villonodular synovitis of the right knee. She presented with a chronic bloody effusion of the knee. The diagnosis of pigmented villonodular synovitis was suggested by the findings on magnetic resonance imaging and confirmed at the time of arthroscopic synovectomy. This report emphasizes the importance of considering pigmented villonodular synovitis in the differential diagnosis of chronic hemarthrosis in children.

Key Words: hemarthrosis, pigmented villonodular synovitis, synovectomy


Pigmented villonodular synovitis (PVS) is a benign but locally aggressive proliferative lesion of the synovial membrane. Monoarticular involvement is the rule, and the knee is the most commonly affected joint. (1), (2) PVS should be suspected in a patient with a chronic joint effusion in whom arthrocentesis yields bloody or brownish synovial fluid. PVS is a rare disorder, with a reported incidence of 1 to 2 per million. (3) PVS occurs most commonly in young adults. It is quite rare in children. This report describes a 9-year-old child with PVS of the knee, and it serves to emphasize the importance of considering PVS in the differential diagnosis of hemarthrosis in children.


The patient in this report presented with a chronic hemarthrosis associated with a large effusion of the right knee. The diagnosis of PVS was suggested by the clinical presentation and MRI findings. The diagnosis was confirmed histologically in synovial tissue obtained at the time of total synovectomy. The patient has experienced a gratifying response to surgical therapy of the PVS.

PVS is a benign proliferative lesion of the synovial membrane. (1), (2) Monoarticular involvement of a knee is the most common clinical presentation. (1), (2) PVS is a rare disorder with a prevalence of 1 to 2 per million. (3) It generally affects young adults. (3) It is particularly rare in children. (4) With the exception of her young age, the patient in the present report had a fairly typical presentation of PVS. She had a chronic, large effusion of one knee with swelling out of proportion to pain and evidence of inflammation. She had bloody synovial fluid despite no evidence of associated bleeding diathesis.


The diagnosis of PVS was suggested by the clinical presentation and by the findings on MRI. The MRI showed a large effusion with scattered hemosiderin deposits. The presence of hemosiderin is considered the most characteristic feature of PVS on MRI. (1) This finding is not pathognomonic for PVS, however. Arthropathy secondary to clotting disorders such as hemophilia and von Willebrand disease must be excluded by appropriate laboratory evaluation. In addition, he moglobinopathies may rarely present as a hemarthrosis. (5)

Grossly, PVS is characterized by thick, plush synovium with long, delicate villi. The synovial villi are orange or reddish-brown in color. (1), (2) PVS may invade the joint capsule and produce erosions of the adjacent cartilage and bone. PVS is characterized by synovial hyperplasia and subsynovial accumulation of histiocytes, multinucleated giant cells, and macrophages containing hemosiderin. In addition to intracellular hemosiderin, there are often extracellular deposits of hemosiderin. (1), (2)

The cause of PVS is unknown. Given the frequent finding of bloody synovial fluid and synovial hemosiderin deposits, chronic or repetitive hemarthrosis represents an attractive cause of PVS. However, the gross and histologic features of PVS differ from hemophilic arthropathy. (6) Moreover, injecting blood or iron into the joints fails to produce all of the clinical and histologic features of PVS. (7), (8) Emerging data suggest that PVS represents a usually benign neoplasm. The tendency to recur after subtotal synovectomy supports the neoplastic theory. More recently, clonal and chromosomal abnormalities in PVS cells have lent support to the neoplastic theory. (9), (10) Rare instances of metastatic PVS suggest that the neoplastic synovium may not always be benign. (11), (12)

The treatment of diffuse PVS is total synovectomy via an open approach or via arthroscope. With either approach, it is difficult to remove all of the synovium, resulting in a risk of recurrence. Some have therefore advocated surgical synovectomy combined with adjunctive radiosynovectomy. (13) The patient in this report did not have adjunctive radioactive therapy because of her age and the potential to affect growth in the radiated joint. As exemplified by the patient in this report, the functional prognosis is good after total synovectomy. (14)


This report describes PVS of the knee in a 9-year-old girl who presented with chronic, painless bloody effusion of a single knee. It serves to emphasize that PVS should be considered in the differential diagnosis of chronic hemarthrosis in children.

Common-sense nerve fibers are seldom medullated before forty--they are never seen even with a microscope before twenty.

--William Osler

From the Division of Immunology and Rheumatology, Department of Pediatrics, University of Virginia Health System, Charlottesville, VA.

The author has no commercial or proprietary interest in any drug, device, or equipment mentioned in this article. I have no financial interest in any item mentioned in this article. I received no financial support from grants or contracts or provision of supplies to write this article.

Reprint requests to Frank T. Saulsbury, MD, Department of Pediatrics, University of Virginia Health System, Box 800386, Charlottesville, VA 22908. Email:

Accepted September 30, 2003.

Copyright [C] 2004 by The Southern Medical Association 0038-4348/04/9701-0080


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(4.) Hoeffel JC, Mainard L, Champigneulle J, et al. Pigmented villonodular synovitis of the wrist in childhood. Clin Pediatr (Phila) 1997;36:423-426.

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(6.) Roosendaal G, van Rinsum AC, Vianen ME, et al. Haemophilic arthropathy resembles degenerative rather than inflammatory joint disease. Histopathology 1999;34:144-153.

(7.) Singh R, Grewal DS, Chakravarti RN. Experimental production of pigmented villonodular synovitis in the knee and ankle joints of rhesus monkeys. J Pathol 1969;98:137-142.

(8.) Roosendaal G, TeKoppele JM, Vianen ME, et al. Blood-induced joint damage: A canine in vivo study. Arthritis Rheum 1999;42:1033-1039.

(9.) Ray RA, Morton CC, Lipinski KK, et al. Cytogenetic evidence of clonality in a case of pigmented villonodular synovitis. Cancer 1991;67:121-125.

(10.) Fletcher JA, Henkle C, Atkins L, et al. Trisomy 5 and trisomy 7 are nonrandom aberrations in pigmented villonodular synovitis: Confirmation of trisomy 7 in uncultured cells. Genes Chromosomes Cancer 1992;4:264-266.

(11.) Choong PF, Willen H, Nilbert M, et al. Pigmented villonodular synovitis: Monoclonality and metastasis--a case for neoplastic origin? Acta Orthop Scand 1995;66:64-68.

(12.) Bertoni F, Unni KK, Beabout JW, et al. Malignant giant cell tumor of the tendon sheaths and joints (malignant pigmented villonodular synovitis). Am J Surg Pathol 1997;21:153-163.

(13.) Shabat S, Kollender Y, Merimsky O, et al. The use of surgery and yttrium 90 in the management of extensive and diffuse pigmented villonodular synovitis of large joints. Rheumatology (Oxford) 2002;41:1113-1118.

(14.) de Visser E, Veth RP, Pruszczynski M, et al. Diffuse and localized pigmented villonodular synovitis: Evaluation of treatment of 38 patients. Arch Orthop Trauma Surg 1999;119:401-404.


* Pigmented villonodular synovitis is a benign but locally aggressive proliferative lesion of the synovial membrane.

* Pigmented villonodular synovitis most commonly presents as a large, bloody effusion of one knee.

* Magnetic resonance imaging in pigmented villonodular synovitis shows synovial hyperplasia and hemosiderin deposition.

* The treatment of pigmented villonodular synovitis is total synovectomy.


A 9-year-old girl presented with a 1-year history of a swollen right knee. Although the knee was markedly swollen, she did not complain of pain, stiffness, or restricted motion of the knee. There was no history of fever or other symptoms suggestive of an underlying rheumatic disease.

Eight months before presentation, the patient was diagnosed as having pauciarticular juvenile rheumatoid arthritis. She was treated with ibuprofen in a dose of 30 mg/kg/d. Despite treatment, the large effusion of the right knee persisted. An arthrocentesis was performed, and it yielded grossly bloody synovial fluid. A cell count was not performed, but cultures of the fluid were negative. Magnetic resonance imaging (MRI) of the right knee showed a large effusion, hyperplasia of the synovium, and scattered hemosiderin deposits (Fig. 1). She was then referred for further evaluation.

Physical examination revealed a very large effusion of the right knee. The right knee was slightly warmer than the left knee, but it was not erythematous or tender to palpation. The range of motion of the right knee was normal. The remainder of the physical examination was normal.

The laboratory evaluation revealed a white blood cell count of 8,800 cells/[micro]l with 56% neutrophils and 40% lymphocytes. The hemoglobin concentration was 12.3 g/dl, and the platelet count was 322,000 cells/[micro]l. The erythrocyte sedimentation rate was 17 mm/h. Tests for rheumatoid factor, antinuclear antibody, HLA-B27, and Lyme disease were all negative. The prothrombin time, partial thromboplastin time, plasma fibrinogen concentration, von Willebrand factor antigen concentration, Factor VIII activity, and ristocetin cofactor activity were all normal. A repeat arthrocentesis again yielded grossly bloody synovial fluid with a hematocrit value of 6%. A cell count of the synovial fluid was not performed. A presumptive diagnosis of PVS was made, and the patient underwent arthroscopy of the right knee.

At arthroscopy, lush, pigmented synovial villi were seen. A total synovectomy was performed. Histologic findings in the resected synovium revealed synovial hyperplasia with subsynovial accumulation of mononuclear cells, giant cells, and numerous hemosiderin-laden macrophages.

The patient experienced gradual resolution of the effusion after the synovectomy. One year after the synovectomy, the patient had a very small residual effusion of the right knee. She had no pain or limitation of motion. She was fully functional and normally active.

Frank T. Saulsbury, MD
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Title Annotation:Case Report
Author:Saulsbury, Frank T.
Publication:Southern Medical Journal
Date:Jan 1, 2004
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