Malignant fibrous histiocytoma associated with hyperlipoproteinemia

A unique case of malignant fibrous histiocytoma arising within the thigh of a patient with Type II A (hypercholesterolemic) hyperlipoproteinemia is described. The tumor, which appeared grossly as a benign tuberous xanthoma, demonstrated pleomorphic spindled and multinucleated cells focally in the distinct storiform pattern of a malignant fibrous histiocytoma and areas composed of bland xanthoma cells associated with cholesterol deposits. Foci of xanthoma cells with mildly atypical nuclei admixed with highly pleomorphic cells were also noted. These unusual histologic features--as well as the uniform staining of all the tumor cells with anti-alpha-1-antichymotrypsin and the absence of anti-alpha-1-antitrypsin and of anti-lysozyme staining--support the conclusion that all elements of this malignant tumor were derived from a common mesenchymal precursor. The exaggerated histiocytic capability of the tumor cells in the form of xanthomatous change was probably in response to the hyperlipoproteinemic microenvironment.