In view of the patient's age, history of left hip pain and one possible imaging differential diagnosis of low-grade malignancy, the patient underwent bone biopsy/curettage. Bone cement and dynamic hip screw placement were also done in the same sitting due to possible risk of pathological fracture in the future. Histopathology of the bone specimen revealed liposclerosing myxofibrous tumor. 

Liposclerosing Myxofibrous Tumor of Bone (LSMFT)

LSMFT is a benign fibro-osseous lesion, which is thought to be a variant of fibrous dysplasia, according to the current genetic data ^1,2. It has a complex histological picture; however, its radiological features and skeletal distribution are relatively classic ¹. In asymptomatic patients, it is often encountered as an incidental finding (41% of cases) whereas in symptomatic patients it may present with nonspecific pain (48% of cases) or pathological fracture (10% of cases) ^1,2. It has an outstanding propensity for the proximal femur, with approximately 85-90 % of lesions occurring in the intertrochanteric region ^1,2. Radiographs commonly show a geographic radiolucent lesion with well-defined, sclerotic margins, suggestive of a slow-growing benign process ².  Bone scan shows variable (mild to moderate) focal increased radiotracer accumulation, which is usually less than the typical intense uptake seen in fibrous dysplasia ¹. Despite the name, no fat component is typically seen on CT or MR images ¹. It has abundant myxoid tissue that is responsible for its low attenuation on CT scans and the increased signal intensity on T2-weighted or fluid-sensitive MR sequences ^{1, 2}.

The differential diagnosis of LSMFT is relatively limited and includes intraosseous lipoma and fibrous dysplasia (often monostotic).

Treatment is variable and depends on the clinical presentation.

These tumors need follow-up imaging due to associated increased risk (10-15%) of malignant transformation to malignant fibrous histiocytoma (MFH) or osteosarcoma when compared with other slow-growing benign fibro-osseous pathologies ^1,2.  Aggressive radiological features (e.g. cortical destruction and associated soft-tissue mass) are suggestive of malignant transformation ¹.