Liposclerosing myxofibrous tumor
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Liposclerosing myxofibrous tumors (LSMFT), also known as polymorphic fibro-osseous lesions of bone, are rare benign fibro-osseous lesions that have a predilection for the intertrochanteric region of the femur.
It is slightly more common in males with mean age of 30-40 years. It can be discovered incidentally but most patients have vague longstanding pain. About 10% of patients present acutely with pathologic fracture.
The tumor comprises of the wide mixture of tissues of lipomatous, fibroxanthomatous, myxomatous, and myxofibromatous components inclusive.
Tends to have a striking predilection for the intertrochanteric region of the femur (80-90%) 1-3.
- geographic lucent lesion usually centered in intertrochanteric region of the proximal femur
- sclerotic margin
- mildly expansile
- matrix calcification in ~70% of cases
- fat density component
Despite its name, distinct fatty components are not seen
- T1: relatively homogeneous and isointense to skeletal muscle
- T2: moderately heterogeneous with areas of high signal due to myxoid component
Scintigraphy can show mild focal uptake with Tc-99m pertechnetate 1.
Treatment and prognosis
- incidentally detected asymptomatic lesions: no treatment or intervention 1
- symptomatic lesions: are commonly managed with bone curettage, bone grafting, and fixation 1
- pathological fracture: uncommon ~10%; proximal femoral lesions may require arthroplasty 1
- malignant transformation: rare but documented 10-15%; transformation into osteosarcoma is the most common
Due to this potential malignant transformation, lesions need follow-up imaging preferably by MRI. Symptomatic lesions or those with interval change require surgical resection 3.
On radiographs consider:
- fibrous dysplasia: it is challenging to differentiate between both by imaging. Fibrous dysplasia may show less sclerosis by radiography, more uptake by scintigraphy and intermediate or low signal intensity by fluid sensitive MRI sequences 1
- intraosseous lipoma: LSMFT does not usually show macroscopic fat on CT or MRI as lipomatous component is usually too small and mixed with other more prominent myxofibrous or fibro-osseous tissue
- aneurysmal bone cyst (ABC): usually more expansile
- 1. Murphey MD, Carroll JF, Flemming DJ et-al. From the archives of the AFIP: benign musculoskeletal lipomatous lesions. Radiographics. 24 (5): 1433-66. doi:10.1148/rg.245045120 - Pubmed citation
- 2. Propeck T, Bullard MA, Lin J et-al. Radiologic-pathologic correlation of intraosseous lipomas. AJR Am J Roentgenol. 2000;175 (3): 673-8. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Campbell K, Wodajo F. Case report: two-step malignant transformation of a liposclerosing myxofibrous tumor of bone. Clin. Orthop. Relat. Res. 2008;466 (11): 2873-7. doi:10.1007/s11999-008-0362-9 - Free text at pubmed - Pubmed citation