Malignant fibrous histiocytoma of the frontal sinus.

The first case of malignant fibrous histiocytoma of the frontal sinus is reported. The aggressive nature of the tumor despite its relatively benign histologic pattern and value of electron microscopy are emphasized. Ultrastructural examination reveals a progression of several principal cell types, lending support to the multi-potent mesenchymal cell origin of these malignancies. These cells may have arisen from the supporting stroma of the ectodermally derived respiratory epithelium of the paranasal sinuses. Wide local excision is currently the primary mode of therapy. The value of radiation therapy or chemotherapy in this tumor in unproven.