Gangliocytic paragangliomas of the duodenum

tions that may result in disfigurement and functional impairment. Other manifestations of the syndrome include neuroendocrine tumors of the duodenum (somatostationomas) and pheochromocytomas. Numerous mapping studies localized the NFl gene on the long arm of chromosome 17 near the centromere and led to cloning of the complete coding region (13). The NFl gene encodes an mRNA of 11-13 kb containing at least 59 exons. Four alternatively spliced NFl transcripts have been identified. NFl appears to be a tumorsuppressor gene. Its product, called neurofibromin, is a GTPase activating protein (GAP)-like polypeptide that appears to down-regulate the RAS oncogene. Over 80% of germllne mutations appear to predict severe truncation of neurofibromin. Somatostatinomas in neurofibromatosis patients are typically pure” tumors and exhibit psammoma bodies in approximately 66% of tumors. Metastatic disease is rare (27%) and mainly confined to lymph nodes (88%)