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Age / Sex : /
Age/Sex : 22/M
C.C.: Left shoulder pain
1) What is your impression?
Courtesy : Kyung Ah Chun, MD Department of Radiology, The Catholic university of Korea, Uijeongbu St. Mary’s Hospital
Diagnosis: lipoma arborescence
Discussion
Findings:
- Plain radiograph of the shoulder shows bone erosion along the superolateral aspect of the humeral head with soft tissue swelling.
- The T1-weighted MR images show frondlike regions of high signal in the joint space representing lipomatous proliferation of the synovium with bone erosion. Fat-suppressed T2-weighted image shows joint effusion with villous proliferation of low signal.
Discussion:
Lipoma arborescens is a rare intra-articular lesion consisting of lipomatous proliferation of the synovium. It occurs in the knee, especially the suprapatellar pouch. Most cases have similar presenting clinical characteristics including an insidious onset of knee swelling usually for many years, followed by progressive pain and debilitation. Exacerbation of clinical findings may be related to trapping of hypertrophied villi between the moving joint surfaces.
MR imaging findings include an intrasynovial frondlike mass paralleling fat in signal with an associated joint effusion. Accompanying joint effusions usually are not specific, although lipoma arborescens with hemarthrosis has been reported.
Lipoma arborescens should be differentiated from synovial lipoma. The former is characterized by diffuse subsynovial deposition of fat and a villous appearance. The differential diagnosis for villous lipomatous proliferation of the synovial membrane includes pigmented villonodular synovitis, synovial chondromatosis, synovial hemangioma and rheumatoid arthritis. With MR imaging, the signal characteristics of the lesion differentiates lipoma arborescens from these other disorders. Lipoma arborescens is almost always associated with other chronic pathology of the joint in the elderly, such as joint effusion, degenerative changes, meniscal tear, synovial cysts, or bone erosions.
References:
1. Ryu KN, Jaovisidha S, Schweitzer M, Motta AO, Resnick D. MR imaging of lipoma arborescens of the knee joint. AJR 1996;167:1229-1232
2. Vilanova JC, Barcelo J, Villaon M, Aldoma J, Delgado E, Zapater I. MR imaging of lipoma arborescens and the associated lesions. Skeletal radiology 2003;32:504-509
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