Final Diagnosis -- Liposclerosing Myxofibrous Tumor

FINAL DIAGNOSIS

Liposclerosing myxofibrous tumor

DISCUSSION

Described in 1986 by Ragsdale and Sweet (1), liposclerosing myxofibrous tumor (LSMFT) is a fibroosseous lesion with a wide range of histologic features that is commonly present in the intertrochanteric region of the femur. The lesion may affect male or females equally in their 4th decade, although younger and older patients can be affected (2). Aside from the femur, it can occur in the humerus, ilium, tibia and ribs (3). Imaging show a non-aggressive lytic or expansile lesion with a sclerotic rim, slow growth in follow up images and may show mineralization (3). Histologically, it shows a bland myxoid and fibrous stroma, adipose tissue, foamy histiocytes, mast cells, curved bony trabeculae and cementum-like ossicles. The differential diagnosis includes other benign entities such as fibrous dysplasia, intraosseous lipoma and non-ossifying fibroma (4). Nevertheless, age, location and the variety of histologic features present in LSMF, help distinguish this lesion from other common diagnoses. It is important to point out that a risk of malignant transformation of up to 10% has been reported in one study (3). GNAS mutations have also been found in some cases (5). Treatment may be in the form of observation for asymptomatic lesion and curettage or joint arthroplasty for symptomatic painful or fractured lesions (4).

REFERENCES

1. Ragsdale BD, Sweet DE. Bone. In: Henson DE, Albores-Saavedra J, eds. The Pathology of Incipient Neoplasia. Philadelphia, PA: Saunders, 1986:381-423.
2. Dattilo J, McCarthy E. Liposclerosing myxofibrous tumor (LSMFT), a study of 33 patients: should it be a distinct entity? Iowa Orthop J. 2012;32(1):35-39.
3. Kransdorf MJ, Murphey MD, Sweet DE. Liposclerosing myxofibrous tumor: a radiologic-pathologic-distinct fibro-osseous lesion of bone with a marked predilection for the intertrochanteric region of the femur. Radiology. 1999;212(3):693-698.
4. Deel C and Lewis H. Liposclerosing myxofibrous tumor. Arch pathol lab med. 2016;140:473-476.
5. Matsuba A, Ogose A, Tokunaga K, et al. Activating Gs alpha mutation at the Arg201 codon in liposclerosing myxofibrous tumor. Hum Pathol. 2003;34(11):1204-1209.

Contributed by Liurka V Lopez, MD and Uma N. M. Rao, MD