MRI features of localized intra-articular form of pigmented villonodular synovitis / 中国医学影像技术

ABSTRACT

Objective To observe MRI features of the localized intra-articular form of pigmented villonodular synovitis (PVNS) within the knee joint. Methods Fifteen patients with pathologically proved localized intra-articular form of PVNS were retrospectively reviewed, and the MRI appearances were observed. Results Solitary nodule or mass within the knee joint was detected in all 15 patients. The lesion located in the infra-patellar fat pads in 11 patients. Most lesions were round or oval, with a well-defined margin. The maximum diameters ranged from 2.0 cm to 6.0 cm, with a mean value of 3.1 cm. The signal intensity of these lesions was characteristically heterogeneous on SE T1WI, TSE PDWI, and TSE T2WI, and the whole signal was similar to that of muscles on SE T1WI and TSE PDWI, but a little higher on TSE T2WI. Prominent low signal intensity on T2WI because of deposition of hemosiderin was found within 14 lesions, and 9 of 15 lesions showed characteristically low signal marginal rim. Conclusion MRI features of the localized intra-articular form of PVNS include a well-defined solitary nodule or mass locating in the infra-patellar fat pad, heterogeneous signal intensity, and prominent interior focal low signal or peripheral low signal rim on T2WI.