Liposclerosing myxofibrous tumour: A traumatized variant of fibrous dysplasia? Report of four cases and review of the literature

Aims: To describe the pathological and radiological features of four cases of liposclerosing myxofibrous tumour (LSMFT). LSMFT is a benign fibro-osseous lesion of bone with a marked predilection for the intertrochanteric region of the proximal femur. It is characterized by a complex mixture of histological elements including fibrous dysplasia-like bony trabeculae, myxofibrous tissue, lipomatous areas, xanthoma cells and pseudo-Paget's bone. This lesion is not a universally accepted pathological entity and often appears in the literature under variants of fibrous dysplasia or other benign lytic bone lesions. Methods and results: All lesions exhibited histological and/or radiological overlap with fibrous dysplasia. A relationship to trauma was noted in three of the cases. The hypothesis that these lesions represent a traumatized variant of fibrous dysplasia was explored. After reviewing the biomechanics of the proximal femur, a possible relationship between predilection of LSFMT for this anatomical region and increased susceptibility to fracture was noted. Conclusions: We hypothesize that when fibrous dysplasia involves the proximal femur, it makes the bone more susceptible to fatigue fracture, thereby altering its histological appearance. The wide variety of histological patterns in LSMFT could represent the end result of repeated reaction to fatigue stresses.