Differentiation between solid pseudopapillary neoplasm of the pancreas and hypovascular pancreatic neuroendocrine tumors by using computed tomography

Background Solid pseudopapillary neoplasm of the pancreas (SPNs) usually showed slight enhancement in contrast-enhanced computed tomography (CE-CT), which is similar to hypovascular pancreatic neuroendocrine tumors (hypo-PNETs). Purpose To show the values of CT imaging features in the differentiation between hypo-PNETs and SPNs. Material and Methods Forty-four patients with histologically confirmed SPNs and 24 patients with hypo-PNETs who underwent preoperative dynamic CE-CT were included. Two radiologists reviewed CT imaging findings and clinical features. Multivariate logistic regression analysis was performed to identify relevant features to differentiate SPNs and hypo-PNETs. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance. Results SPNs usually occurred in young women compared with hypo-PNETs (mean age = 34.5 years vs. 49.08 years, P < 0.01). SPNs usually showed an oval shape, “floating cloud” sign, calcification, and lower frequencies of metastases compared with hypo-PNETs ( P < 0.05 for all). The combined features (lower age, “floating cloud” sign, and calcification) showed acceptable diagnostic performance (area under the curve [AUC] = 0.865 with 100% sensitivity and 63.6% specificity) for differentiating SPNs from hypo-PNETs. Conclusion “Floating cloud” sign, lower age, and calcification have great potential in differentiating SPNs from hypo-PNETs.