COLONIC HISTIOCYTIC NEOPLASM MIMICKING MALIGNANT HISTIOCYTOSIS AND PRESENTING AS INTUSSUSCEPTION

It is now apparent that distinction between the so-called malignant hi stiocytosis and lymphoma can be made using panels of established immun ohistochemical markers and/or genotypic analysis. Many, if not all, of the previously diagnosed cases of malignant histiocytosis have been s hown to be of lymphoid, rather than histiocytic, lineage. We report a rare case of colonic histiocytic neoplasm accompanied by a lymphoretic ular dissemination that mimicked that of malignant histiocytosis. In a ddition, barium studies and computed ;udal tomography confirmed an int ussusception that subsequently developed. The histiocytic nature of th e neoplastic cells was supported by immunohistochemical, ultrastructur al, and cytochemical studies. To our knowledge our case may represent the fifth documented case of a histiocytic malignancy reported in the literature. The relationship among the various cases will be discussed as web as the significance of the focal S-100 immunoreactivity observ ed in the present case. This is a US government work. There are no res trictions on its use.