Age / Sex : 20 / M

Chief complaint : right hip pain (onset: 7 years ago, aggravated 1 month ago)

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy of Geun Young Lee, Chung-Ang University Hospital

Discussion

Answer: Pigmented villonodular synovitis (PVNS), right hip joint

Findings: Dark SI intra-articular mass on FS T2WI, with joint effusion. Tiny nodular lesion around ligamentum teres, also.

Differential Diagnosis: (1) lipoma aborescens (2) synovial osteochondromatosis (3) siderotic synovitis

Discussion: Pigmented villonodular synovitis (PVNS) is a rare synovial disease involving any joint, bursa or tendon sheath, which is divided into two forms- a localised form or nodular tenosynovitis, and diffuse-type (extra-articular) giant-cell tumor. The hip is less frequently affected (15%) than the knee (70%).Clinical manifestation of PVNS is non-specific. Pain is most common symptom. PVNS usually affects a single joint, rather than multiple joints. In general, there is no specific finding on plain radiography or CT, however, osteolytic lesion or erosion may be seen by synovial proliferation. MRI can show the lesion about its location/extent and characteristics, showing intermediate to low signal intensity on T2WI and strong enhancement, with blooming artifact on gradient echo image by hemosiderin deposition.

References: Sylvain Steinmetz, Anne-Laure Rougemont, Robin Peter. Pigmented villonodular synovitis of the hip. EFORT Open Rev. 2016 Jun; 1(6): 260–266.