Analysis of the CT and MRI findings for benign and malignant solid pseudopapillary pancreatic tumor

Objective: To analyze and summarize the characteristic diagnostic points of CT and MRI images for benign and malignant solid pseudopapillary pancreatic tumors. Results may have applications in improving the accuracy of these imaging modalities. Methods: A total of 38 cases of solid pseudopapillary tumors (SPT) and 10 cases of solid pseudopapillary carcinomas (SPC) confirmed through surgery and pathology were retrospectively analyzed. The characteristic and diagnostic points of CT and MRI images were analyzed and summarized. Results: Thirty-eight cases of SPT had complete capsules, which were characterized low signal on T1 and T2, and delayed enhancement after contrast injection. Nine cases of SPC had incomplete capsules. Eighteen cases of SPT and 6 cases of SPC showed punctate, nodular, or arcing calcification. A total of 11 cases of SPT hemorrhage and 6 cases of SPC hemorrhage were observed. CT scanning showed elevated T1 density and signals and attenuated T2 signals. Moreover, 7 cases of SPT and 5 cases of SPC showing duct, tubular, or beaded dilation; 4 cases of SPC with peripheral vessel invasion and unclear vascular walls; and 5 cases of SPC with surrounding tissue invasion were observed. Conclusions: Capsulation, calcification, intratumoral hemorrhage, pancreatic duct dilation, and vascular and surrounding tissue invasion are the characteristic diagnostic points of SPT and SPC on CT and MRI images. Capsulation, blood vessel characteristics, and surrounding tissue invasion may serve as key points for the differential diagnoses of benign and malignant SPT. (authors)