Endoscopic ultrasound appearance of pancreatic serotonin-staining neuroendocrine neoplasms

Background/Objectives: The pancreatic localization of serotonin-staining neuroendocrine neoplasms is extremely rare. This is a retrospective study aimed at analyzing the endoscopic ultrasound appearance of pancreatic serotoninoma. Methods: Between 2010 and 2016, all consecutive patients with histologically proven pancreatic serotoninoma who had undergone endoscopic ultrasound were enrolled. Results: Eight patients (six F, median age 68.5 years) had a diagnosis of pancreatic serotoninoma and underwent endoscopic ultrasound examinations. Median diameter of the lesion was ten mm. The nodule echotexture was hypoechoic in seven out of eight cases. The most frequent localization was the pancreatic neck (four); in three cases, the tumor was located in the pancreatic head and in one in the body. In seven cases the tumor caused a main pancreatic duct dilation; in three cases also the secondary ducts were dilated. In one case a dilation of the common bile duct was observed. At contrast-enhanced endoscopic ultrasound no one showed the typical contrast-enhancement. Elastography (available in two patients) showed a rigid pattern of the lesion. Conclusions: From this case series a specific endoscopic ultrasound appearance resulted for pancreatic serotoninoma, different from other types of pancreatic neuroendocrine neoplasm, but it is difficult to differentiate it from a pancreatic adenocarcinoma or an intraductal papillary mucinous neoplasm.