Age / Sex : 58 / M

Chief complaint : left hip pain (duration: 5-6 months)

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 : Guen Young Lee, Chung-Ang University Hospital

Discussion

Answer:  synovial osteochondromalatosis

Findings: Increased opacity lesion anterior to left femoral head on plain radiography and CT scan, is correlated with low signal intensity on T1WI and increased signal intensity on T2WI, without enhancement and inner flow-void dark signal intensity portion.

On arthroscopy, moderate hypertrophied synovitis as well as discrete hyaline cartilage nodules were identified including about 6cm sized large nodule anterior to femur head, and synovial osteochondromatosis was confirmed.

Differential Diagnosis:

• juxtacortical chondroma


• BPOP (Bizarre parosteal osteochondromatous proliferation)

Discussion:

Synovial chondromatosis is a benign condition characterized by the formation of multiple intrasynovial cartilaginous or osteocartilaginous nodules arising from joint synovium, tendons or bursae. It usually affects the large synovial joints such as knee, elbow, or hip joints, and more frequently occurs in males with fifth decades of ages.

The loose bodies remain free floating, or conglomerate into a large mass, such as giant synovial chondroma. Soft tissue nodules with calcification are common finding on plain radiography or CT scan, sometimes associated with osteoarthritis. On MRI, the majority of intra-articular nodules show intermediate signal intensity on T1WI and increased signal intensity on T2WI with/without focal signal void, correlated with ossificiation.

References:

Mark J. Kransdorf, Mark D. Murphey-Imaging of Soft Tissue Tumors-Lippincott Williams & Wilkins (2006)