Human bilharzial ureters: III. Fine structure of the egg granuloma.

The fine structure of egg granuloma forming cells is described in lower ureteral segments of patients chronically infected with Schistosoma haematobium. The infiltrates consisted of monocytes, macrophages, lymphocytes, plasma cells, neutrophils, eosinophils, fibroblasts, mast cells, and blood platelets. The abundant monocytes and macrophages were actively mobile and intensively phagocytic cells. Multinucleate giant macrophages were only seen within empty egg shells. In addition to normal looking lymphocytes and plasma cells, several lymphocyte-like Sezary cells characterized by strikingly convoluted "cerebriform" nuclei were observed. Mature neutrophils and eosinophils were detected in addition to abnormal looking neutrophils; these contained numerous filamentous bundles. Fibroblasts were associated with extracellular collagen fibers and an electron-dense material. The few mast cells seen in proximity to blood vessels have a feature consistent with the onset of degranulation. Few blood platelets with active phagocytic features were among the granuloma cells.