gangliocytic paragangliomas ( gps ) are rare and peculiar benign tumors , encountered mostly in the periampullary area of the duodenum   and much less frequently in the jejunum or third part of the duodenum . some studies have reported that approximately 90% of gps are found in the second part of the duodenum , from where the tumor can invade the ampulla of vater ( aov ) . gps of the duodenum may present as incidental endoscopic and radiologic findings or as gastrointestinal bleeding due to ulceration of the overlying mucosa . gastrointestinal bleeding is the most common clinical presentation , followed by abdominal pain and anemia . we present the case of a 41-year - old female with gp of the duodenum , along with the clinical data , histology , and immunohistochemical staining results that correlated well with previously reported characteristics of duodenal gps . a 41-year - old female was admitted due to a history of abdominal pain . on admission , contrast - enhanced computed tomography ( ct ) revealed a well - defined , enhancing , 2-cm , oval - shaped mass in the second portion of the duodenum , adjacent to the aov . magnetic resonance cholangiopancreatography showed a well - defined , 2-cm , oval - shaped subtle t2 hyperintense lesion in the second portion of the duodenum , adjacent to the aov , as well as a normal common bile duct . upper gastrointestinal endoscopy revealed a 2-cm subepithelial tumor in the ampullary portion of the duodenum ( fig . histopathology revealed spindle cells , ganglion - like cells , and epithelioid cells in the submucosal layer of the duodenum ( fig . this case showed characteristic histologic features of a tumor composed of three cell types ( epithelioid , spindle , and ganglion ) , which classified the tumor as a gp . 4 ) . histology showed a well - demarcated lesion in the submucosal layer of the duodenum ( fig . a follow - up upper gastrointestinal endoscopy performed 2 months later revealed scar formation in the resection site with convergence of the surrounding folds . various theories of the pathogenesis of duodenal gps have been proposed , but the histogenesis of these tumors is uncertain . a gp is known as a " 10% tumor , " based on the frequency of the inherited forms of the disease . approximately 30% of gps show 10 types of susceptibility gene ( " 10-gene tumor " ) . advances in the genetic studies of paragangliomas will have important consequences for the monitoring of patients , from genetic counseling to personalized clinical management . typical histologic patterns of gp include an admixture of ganglion - like cells , carcinoid tumor - like areas , and spindle cell proliferation . immunohistochemical staining of this tumor showed a strong positive reaction for the s-100 protein in the spindle cells , while the epithelioid and ganglion - like cells expressed synaptophysin ( fig . several authors have reported that the epithelioid and ganglion cells are positive for neuroendocrine peptides , such as somatostatin , pancreatic peptide , and serotonin . the incidence of gps is slightly higher in males than in females ( 1.8:1 ) , and the mean age of appearance is 54 years ( range , 17 to 83 ) . gps are considered benign even though they occasionally involve the regional lymph nodes and display distant metastasis or tumor recurrence , features suggestive of malignancy . the characteristic ulceration and bleeding of the overlying mucosa lead to the usual clinical manifestations of melena and sometimes massive hematemesis and unexplained anemia . approximately 50% of patients seek medical attention for gastrointestinal bleeding , but this case did not have a history of gastrointestinal bleeding episodes . duodenal gps are larger than 1.5 cm in at least one dimension and tend to be ulcerated and to bleed . obstructive jaundice is less common in ampullary gp , but obstructive jaundice due to paragangliomas has been reported . the majority of reported duodenal gp cases have been benign in nature , and simple excision of the tumor is deemed sufficient . the emr procedure is safe and easy to perform , because the tumor protrudes into the duodenum . when endoscopic resection is not possible , surgical resection is indicated , and when regional lymph nodes are positive for metastasis , pancreaticoduodenectomy followed by local radiotheraphy is recommended . because the possibilities of recurrence and metastasis can not be excluded completely , decisions on the treatment method to use must be made after careful preoperative staging of the disease prior to local treatment . furthermore , continuous follow up at the outpatient department for early detection of recurrence is necessary .