Duodenal periampullary gangliocytic paraganglioma: Report of two cases with immunohistochemical and ultrastructural study

We report two cases of Gangliocytic Paraganglioma (GP) of the ampulla of Va ter occurring in a 63-year-old* and a 34-year-old** individual. The patient s were both admitted for a long history of intermittent gastrointestinal bl eeding and abdominal discomfort with no other symptoms. At endoscopy, the G P appeared as a polypoid, ulcerated mass in the ampullar region, measuring 2.5x1.8* and 2 cm**, respectively. Microscopically, the tumors showed simil ar features and were composed of epithelial cells (more than 50%), spindle cells, and ganglion-like cells. The epithelial cells showed clear cytoplasm and formed nests (zellballen or paraganglioma-like groups), and less frequ ently, cords (carcinoid-like), extending to mucosa and submucosa. Ganglion cells were sparse, constantly associated with the spindle cells. Both epith elial and ganglion cells were synaptophysin, chromogranin A, and anti-neuro filament immunoreactive. The spindle cells were all S-100 positive. Ultrast ructural studies revealed dark and light cells, rare elongated cellular pro cesses, secretory granules, and fine fibrils resembling neurofilaments. The histogenesis of GP is still a matter of debate, however its neoplastic nat ure is supported by the occasionally reported malignant evolution.