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Age / Sex : 44 / M
C.C.: Dull pain around the left hip joint for 5 months
1) What is your impression?
2) A first impression and three or less differential diagnoses are acceptable.
Courtesy: Seon-Kwan Juhng, MD., Wonkwang University School of Medicine Hospital
Diagnosis: intraoseous lipoma
Discussion
Findings:
1) AP and axial views of the left hip joint show an expansile osteolytic intramedullary lesion in the intertrochanteric region of the proximal femur having peripheral and central calcifications.
2) MR shows an elongated medullary cystic lesion with low signal intensity on T1WI, high signal intensity on T2WI, and peripheral rim enhancement on fat saturated contrast ehanced T1 weighted images. There is an amorphous dark signal intensity area centrally, consistent to the internal calcification on plain radiographs.
Differential Diagnosis:
- Intraosseous lipoma, Liposclerosing myxofibrous tumor, Infarction of bone, Enchondroma, Fibrous dysplasia, Chondromyxoid fibroma, Myxoma of bone
Diagnosis: Intraosseous lipoma
Discussion:
- Intraosseous lipoma may be a less rare lesion than has previously been suggested. Clinically, the lesion is often asymptomatic and is discovered incidentally. When they consist of live fat cells, lesions are quite radiolucent, demonstrate resorption of preexisting bone, and may be expainsile. In other cases, varying zones of fat necrosis are responsible for increased radiographic density due to fat calcification and reactive bone formation. Proximal femur or calcaneus is more common for the lipoma, but lesion has presented in all regions of the skeleton.
- The surgical features vary between solid fat, cystic lesions with fat necrosis, and differing amounts of very sclerotic bone and calcified fat. Because of the spontaneous occurrence of involutional changes with these lesions, which produce dramatic alterations of the radiologic and pathologic features, the intraossous lipoma can be staged into three separate clinical patterns: stage 1, in which there is no secondary necrosis; stage 2, in which there is partial secondary necrosis; and stage 3, in which there is complete or near-complete secondary necrosis.
- Diagnosis of intraosseous lipoma may be suggested by radiologic findings of unusual but very characteristic calcification and ossification occurring both in the central and peripheral portions of the lesions, like this case.
References:
1. Milgram JW. Intraosseous lipoma:radiologic and pathologic manifestations. Radiology 1988;167:155-160
2. Milgram JW. Intraosseous lipomas with reactive ossification in the proximal femur. Report of eight cases. Skeletal Radiol;7:1-13
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