Liposclerosing myxofibrous tumor of the proximal femur: a case report

Abstract

Liposclerosing myxofibrous tumor (LSMFT) is a rare fibro-osseous lesion with a strong predilection for the proximal femur, rarely seen in clinical practice and often diagnostically challenging. A 29-year-old woman who presented with left hip pain after a fall is reported. Multimodal imaging — plain radiographs, computed tomography, and magnetic resonance imaging (MRI) — was performed, followed by intraoperative frozen section analysis and curettage. The residual cavity was filled with a synthetic bioactive-glass bone substitute, and the proximal femur was stabilised with a dynamic hip screw (DHS). Plain radiographs showed a geographic lytic lesion in the subtrochanteric femur with a thick sclerotic rim. Computed tomography confirmed well-defined medullary expansion with heterogeneous mineralisation. MRI demonstrated marked T2 hyperintensity consistent with myxoid stroma. Intraoperative frozen section showed a benign-appearing spindle-cell lesion; permanent histopathology on a 10×8×2 cm curettage specimen confirmed LSMFT, demonstrating the characteristic polymorphic combination of xanthomatous foci, mature adipocytes, fibrous stroma, and myxoid areas without malignant features. At the latest follow-up, 4 months postoperatively, the patient was pain-free (visual analogue scale 0) with a full, unrestricted hip range of motion and a Harris Hip Score of 99.8; full weight-bearing had been resumed by the second postoperative month. Follow-up radiographs demonstrated incorporation of the graft without evidence of local recurrence, and no complications were recorded. This case highlights the diagnostic challenges of LSMFT, the limitations of intraoperative frozen section in polymorphic fibro-osseous lesions, and the importance of structural fixation at the subtrochanteric level. Although the short-term outcome was excellent, lifelong surveillance is warranted given the reported risk of malignant transformation.