Age / Sex : 29 / F

Age / Sex : F/29

Chief complaint :

Rt. Knee pain and swelling for several years

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to In Sook Lee, MD (lis@pusan.ac.kr)

Courtesy :

PVNS

Discussion

Findings:

Joint effusion with diffuse low signal lining hypertrophied synovium on T2WI, showing contrast enhancement.

Differential Diagnosis:

Differential diagnosis on the basis of MR findings includes hemophilia, rheumatoid arthritis, and amyloid arthritis[1]. Differential diagnosis of intra-articular lesions includes synovial hemangioma, PVNS, hyperplastic synovitis,  synovioma,  and  lipoma  arborescens[1].

Diagnosis: 

Pigmented villonodular synovitis

Discussion:

Pigmented villonodular synovitis (PVNS) is a benign, neoplastic disease with synovial proliferation of uncertain etiology[1]. Synovium exhibits villous and/or nodular changes with iron and fat deposition[2]. PVNS is commonly seen in patients in the 3rd and 4th decades of life with unilateral and monoarticular involvement[3]. Rare cases of multifocal PVNS have been reported in the literature. The sex incidence is equal. PVNS is a rare disease with an incidence of 1.8 cases per million people per year. Even though diffuse PVNS can affect any joint, it most commonly affects large joints of lower extremity, with 80% involving the knee. Pain accompanied by locking and decreased range of motion is a common presenting symptom. Physical examination includes swelling and tenderness to palpation. PVNS is caused by an inflammatory response with hyperplasia of undifferentiated connective tissue cells of the synovial membrane[4]. The present classification includes localized, pigmented, nodular synovitis and diffuse PVNS affecting the entire synovial membrane of a joint or bursa.

Magnetic resonance (MR) imaging (MRI) is a noninvasive, highly accurate diagnostic modality in characterizing PVNS[5]. Apart from diagnosis, MRI also is useful in defining the extent of disease. On MRI, multinodular, intra-articular lesions with patchy areas of hemosiderin and fat are diagnostic of PVNS[2]. Contrast enhancement MR study may show a slower enhancement rate. High enhancement is due to inflammation and increased vascularity of synovitis[6].

References:

1.       Lee, F.Y., et al., A discrete soft tissue mass in the distal thigh of a 29-year-old man. Clin Orthop Relat Res, 1998(357): p. 247-50, 255-6.

2.       Goldman, A.B. and E.F. DiCarlo, Pigmented villonodular synovitis. Diagnosis and differential diagnosis. Radiol Clin North Am, 1988. 26(6): p. 1327-47.

3.       Bhimani, M.A., J.F. Wenz, and F.J. Frassica, Pigmented villonodular synovitis: keys to early diagnosis. Clin Orthop Relat Res, 2001(386): p. 197-202.

4.       Cotten, A., et al., Pigmented villonodular synovitis of the hip: review of radiographic features in 58 patients. Skeletal Radiol, 1995. 24(1): p. 1-6.

5.       Flandry, F., et al., Roentgenographic findings in pigmented villonodular synovitis of the knee. Clin Orthop Relat Res, 1989(247): p. 208-19.

6.       Dale, K., et al., Dynamic MR-imaging in the diagnosis of pigmented villonodular synovitis of the knee. Scand J Rheumatol, 2000. 29(5): p. 336-9.