Xanthomatous lesions of the mandible: osseous expression of non-X histiocytosis and benign fibrous histiocytoma.

Seven cases of xanthomatous lesions of the mandible, followed from 1 to 18 years, are documented. All lesions were benign and painless; radiographic appearances varied from single and well-demarcated to diffuse and multilocular. Microscopic examination showed sheets of histiocytes with xanthoma or foam cells, fibroblasts and fibrous tissue, and inflammatory cells as well as cells in transition, with characteristics of both histiocytes and fibroblasts. Immunohistochemical staining and electron microscopic observation provided further evidence of the biphasic nature of this cell population. Twelve similar cases were found in the literature under a variety of diagnostic or descriptive labels. Our findings show that these lesions are histiocytic in nature and that they range from small, innocuous lesions, which we regard as the osseous counterpart of non-X histiocytosis, to larger, more destructive lesions diagnosed as benign fibrous histiocytoma (fibrous xanthoma) of bone.