an intrapancreatic accessory spleen may be misdiagnosed as a nonsecreting neuroendocrine tumor of the pancreas . an accurate diagnosis is crucial since such an accessory spleen does not require surgical treatment . a 67-year - old woman in good general conditions with a family history positive for pancreatic cancer underwent a routine health check . physical examination was normal and laboratory tests revealed normal alpha fetoprotein and carcinoembryonic antigen but a slightly elevated tumor marker ca 19 - 9 ( 35 u / ml ; normal < 27.0 u / ml ) . additional laboratory tests such as chromogranin a , neuron - specific enolase , 5-hydroxyindoleacetic acid , pancreatic polypeptide and substance p were ordered and normal beside a slightly elevated pancreatic polypeptide level ( 437 pg / ml ; normal < 210 pg / ml ) . the patient also underwent a ct scan investigation which showed a 18  15  15 mm nodular lesion in the tail of the pancreas without any contrast enhancement ( fig . an additional octreotide scan was normal . because of the abnormal tumor markers ca 19 - 9 and pancreatic polypeptide , a neuroendocrine tumor was suspected , although the image appearances were not typical . due to this potentially malignant lesion intraoperatively , a dark red but soft tumor was found in the tail of the pancreas and the lesion was also confirmed by intraoperative sonography . postoperative histopathological examination revealed a completely intrapancreatic accessory spleen without any signs of a tumor ( fig . during the 5th week of gestation the spleen develops in the dorsal mesogastrium from mesenchymal cells that migrate between the leaves of the mesentery and coalesce . an accessory spleen may arise from isolated cells which rest separated from the main body of the spleen . in a large series of nonselected autopsy investigations an accessory spleen was found in 1030% [ 1 , 2 ] . in 1,000 consecutive patients undergoing contrast - enhanced abdominal ct scan an accessory spleen was present in 16% . in 80% the accessory spleen is located at or near the splenic hilum . differential diagnosis of a solid pancreas tumor includes pancreatic adenocarcinoma , pancreatic neuroendocrine tumor , solid and papillary epithelial neoplasms and metastasis . pancreatic endocrine tumors are rare ( < 10% ) and often localized in the head of the pancreas [ 4 , 5 ] . due to secretion of biologically active substances , 1553% of these tumors become symptomatic , all others remain initially silent . however 50% of these nonsecreting endocrine tumors only 11 cases of surgical resection of an intrapancreatic accessory spleen have been reported up to now . in most of these cases the intrapancreatic accessory spleen was misdiagnosed as a pancreatic tumor and patients underwent unnecessary surgery . most intrapancreatic accessory spleens are roundish and have a characteristic homogenous contrast - enhanced appearance on ct scan with well - defined margins . however , definitive diagnosis based on imaging can be difficult because ct scan , mri and ultrasound images of such intrapancreatic spleens are quite similar to those of hypervascular pancreatic tumors , as islet cell tumors and acinar cell carcinoma . using contrast - enhanced ultrasound , ota and ono   demonstrated in the hepatosplenic phase that contrast medium is trapped by hepatic and splenic tissue , which may allow to distinguish an intrapancreatic spleen from other lesions . somatostatin receptor scintigraphy ( octreotide scan ) has a high sensitivity in detection of gastrointestinal neuroendocrine tumors ( 7095% ) . the presence of somatostatin receptors on the surface of lymphocytes within the splenic tissue , which also bind octreotide with a high affinity , may therefore mimic a neuroendocrine tumor [ 10 , 11 ] . diagnosed in three of five patients an intrapancreatic accessory spleen based on the findings of standard gadolinium - enhanced mri . however , they were not able to exclude other diagnoses with this investigation , including pancreatic neuroendocrine tumors , pancreatic adenocarcinomas , solid and papillary epithelial neoplasms , and metastasis . the only possibility to differentiate an accessory spleen from a neuroendocrine tumor are nuclear scintigraphic investigations as 99 m tc - sulphur colloid or tc - tagged heat - damaged red blood cells scintigraphies . these are investigations which are noninvasive , sensitive and specific for detecting splenic tissue [ 13 , 14 ] . in asymptomatic homogenous and well - circumscribed tumors in the pancreatic tail an accessory spleen has to be excluded before surgery . nuclear scintigraphies such as 99 m tc - sulphur colloid or tc - tagged heat - damaged red blood cells scintigraphies should be definitely routinely used in the preoperative evaluation of nonsecreting pancreatic lesions , particularly those which are located in the body and tail of the pancreas . these imaging modalities may provide the definitive diagnosis of an intrapancreatic spleen and therefore prevent patients from undergoing unnecessary major surgery .
in a large series of nonselected autopsy investigations an accessory spleen was found in 1030% . 
 the second most common site is the pancreatic tail ( 17% ) . 
 we report a case of intrapancreatic accessory spleen misdiagnosed as a nonsecreting neuroendocrine tumor of the pancreas . 
 nuclear scintigraphy may provide the definitive diagnosis of an intrapancreatic spleen and therefore prevent patients from unnecessary major surgery .