BackgroundPancreatic neuroendocrine tumors (pNETs) and solid pseudopapillary tumors (SPTs) are two of the most common pancreatic neoplasms with different treatment procedures. However, the broad heterogeneity of pNETs and SPTs in clinical manifestations and radiological features often confuse the presurgical discrimination in clinical practice, and the clinical and molecular differentiation of the two tumors remains elusive to date. We presume that a large and comprehensive study into the multimodality features of pNETs and SPTs is necessary for precise clinical management.MethodsWe collected and analyzed the clinicopathological information and multimodality features of nonfunctional pNET and SPT patients, for a total of 631 cases from 2006 to 2021. Univariate analysis of imaging features, including contrast-enhanced computed tomography (CT), magnetic resonance imaging, endoscopic ultrasound (EUS) and nuclear medicine imaging, and clinical characteristics was performed, and CT features and clinical information were integrated to establish a nomogram model.ResultsWe recruited 354 nonfunctional pNET and 277 SPT patients in our cohort. Regarding demographic information, pNET patients had a lower female percentage (55.4% vs. 72.9%), smaller tumor size (2.8 vs. 4.8 cm), and older age (53.4 vs. 35.3 years). In CT imaging and EUS, pNETs tended to appear as solid and homogenous lesions with strong enhancement intensity. Multifocal lesions, duct dilation, and lymph node (LN) enlargement were more likely to be observed in pNETs, while calcification was more common in SPT lesions. On positron emission tomography (PET)/CT, pNETs exhibited significant sensitivity to somatostatin receptor scintigraphy (SRS), with positive rates of 81.4% and 95% on 99mTc-HYNIC-TOC and 68Ga-DOTATATE PET/CT, respectively, while SPTs were all negative on SRS. Multivariate analysis identifies tumor size, age, enhancement intensity, calcification, and LN enlargement as statistically significant variables.ConclusionsCompared to SPT patients, pNET patients exhibit an older age and smaller tumor size. CT manifestations of strong intensity, LN enlargement, and no calcification could indicate a higher possibility of pNET. Meanwhile, the similarity in the immunohistochemical profile indicates that the two tumors could potentially develop from the same origin.

ObjectivesSomatostatin receptors are commonly expressed in most pancreatic neuroendocrine tumors (pNETs), a rare type of pancreatic tumors with high heterogeneity. However, the role of somatostatin receptor 2 (SSTR2) has seldom been investigated separately in pNET. This retrospective study aims to evaluate the role of SSTR2 in the clinicopathological features and genomic background of nonfunctional and well-differentiated pNET.MethodsA total of 223 cases of nonfunctional well-differentiated pNET were included, and the correlation between SSTR2 status and clinicopathological outcome was evaluated. In addition, we performed whole exome sequencing in SSTR2-positive and SSTR2-negative pNETs and identified that the 2 lesions harbored different mutational landscapes.ResultsNegative SSTR2 immunochemistry staining was significantly related to an earlier onset of disease, larger tumor size, advanced stage of American Joint Committee on Cancer, and tumor metastasis in lymph nodes and liver. Under pathological assessment, positive peripheral aggression, vascular invasion, and perineural invasion were markedly increased in SSTR2-negative cases. Moreover, SSTR2-negative patients exhibited significantly worse progression-free survival than SSTR2-positive patients (hazard ratio, 0.23; 95% confidence interval, 0.10–0.53; P = 0.001).ConclusionsSomatostatin receptor 2–negative nonfunctional pNET might represent a subtype of pNET with poor outcomes and evolve from a different genomic background.