Benign fibrous histiocytoma of bone.

The cases of seven patients who had a lytic lesion that was histologically similar to a metaphyseal fibrous defect (non-ossifying fibroma) of bone were studied. The patients all were adults and had pain without a fracture. These features were considered distinctive for the lesion, which has the same histological appearance as benign fibrous histiocytoma of soft tissue. The lesion is a benign tumor with fibroblastic and histiocytic differentiation. This picture may be seen in foci in other lesions of bone (aneurysmal bone cyst, fibrous dysplasia, and giant-cell tumor). Ten cases of giant-cell tumor of bone that had a large component of the same foci were also reviewed. It should be emphasized that these areas are secondary reactive tissue rather than the true neoplastic tissue of benign fibrous histiocytoma.