malignant fibrous histiocytoma:

Malignant fibrous histiocytoma (MFH) is a malignant tumor of soft parts observed at approximately 70% of cases situated at the level of the outsides.

Malignant fibrous histiocytoma (MFH) of bone is a distinct entity from fibrosarcoma and was first described in the 1970's.⁵ Like fibrosarcoma, MFH more commonly arises in soft tissue (soft tissue sarcoma). Histologically, these lesions are composed of a heterogeneous population of cells. MFH often contain areas of swirling (storiform) spindle-shaped cells and giant cells. This, too, can resemble fibroblastic osteosarcoma and it takes an experienced pathologist to distinguish between these lesions.

How Is Fibrosarcoma Similar Or Different From Other Bone Sarcomas?

As the name implies, fibrosarcoma results from abnormal fibroblast cell division. Osteosarcoma and chondrosarcoma are distinguished by the extracellular matrix (material) the malignant cells produce. Osteosarcoma is characterized by production of osteoid (the organic matrix of bone) whereas chondrosarcoma neoplasms make abundant cartilage. In contrast, fibrosarcomas produces neither bone nor cartilage. Collagen is the predominant product produced by the malignant cells in fibrosarcoma. The amount of collagen production is inversely proportional to the histological grade (grade to be reviewed later) (i.e., high grade tumors produce less collagen and vice versa). It is the rapidly dividing and spreading cells in sarcoma (not the matrix produced) that can threaten life and limb.

Distinguishing between different bone tumors can be challenging. The differential diagnosis for any given bone lesion often includes both benign and malignant processes. Lesions that may appear similar to fibrosarcoma on radiographs include malignant solitary fibrous tumor, leiomyosarcoma, myofibromatosis, myeloma, osteosarcoma, lymphoma, metastatic disease, malignant fibrous histiocytoma of bone, and desmoplastic fibroma.³