Pigmented Villonodular Synovitis (PVNS) of the Ankle

Figures 1&2: Sagittal MR images in T1 (fig.1) and STIR (fig.2) show a heterogeneous para-articular mass (arrows) anterior to the ankle joint that demonstrates areas of internal low T1 and T2 signal intensity (arrowheads), consistent with hemosiderin deposits.

Facts: PVNS

• Inflammatory synovial lesion of unknown etiology
• Young to middle-aged adult, usually male
• Histology shows connective tissue hyperplasia, phagocytes and hemosiderin deposition
• Two types: localized and diffuse
• Common involvement: knee, hip, ankle/foot
• It is a "joint" disease that can produce mass and erode adjacent bones
• MRI is the imaging modality of choice for suspected case of PVNS

MR Imaging Features

• Heterogeneous para/intra-articular soft tissue mass with low T1 and T2 signal (due to hemosiderin deposition)
• Blooming of low T2 areas in gradient echo imaging
• Diffuse intense enhancement
• Variable amount of joint effusion
• Imaging mimics: rheumatoid arthritis, hemophiliac joint, amyloidosis

Reference:

Ofluoglu O. Pigmented villonodular synovitis. Orthop Clin N Am 2006;37:23-33.

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