Gangliocytic paraganglioma of the duodenum: case report.

A case of gangliocytic paraganglioma of the duodenum, the 25th in world medical literature, is reported. The histologic appearance consists of epithelioid cell nests resembling "Zellballen" of carotid body tumors, together with gangliocyte-like elements. Ultramicroscopically, the cytoplasm of the cells contains round electron-dense granules or a large number of filaments. Occasional cells contain both granules and filaments.