Inflammatory fibrous histiocytoma (? anthogranuloma). Report of two cases with ultrastructural observations in one.

Two cases of inflammatory fibrous histiocytoma are presented, one occupying the pleural space, and the other the retroperitoneum. One of the cases was studied with the electron microscope and confirmed the histiocytic and xanthomatous nature of the lesion. It is suggested that the term xanthogranuloma be replaced by fibrous histiocytoma, and that when a considerable inflammatory component is present in the stroma, a guarded prognosis be entertained. Ultrastructurally there are no distinctive features for the inflammatory variant of the fibrous histiocytoma.