Imaging Characteristics And Pathologic Basis Of Solid Pseudopapillary Tumor Of Pancreas

ObjectiveThis study aimed to evaluate the Computed tomography (CT) and magnetic resonance imaging (MRI) features of solid pseudopapillary tumor of the pancreas (SPTP) with pathologic correlation.MethodsCT and MRI findings of SPTP in38adults proved by clinic and operation were analyzed retrospectively. Among them,35cases were female and the other3were male with the mean age range of31.3years old. All of the cases had taken CT and MRI plain and enhanced scan. We analyzed the relationship between the pathology findings and tumor’s cross-sectional imaging features including location, size, shape, capsule, density/signals and the way of strengthen. According to the tumor size, all cases were divided into group A (≤2.0cm,5cases), group B (2.0cm-5.0cm,18cases) and group C (≥5.0cm,15cases). We compared tumor’s cross-sectional imaging features to their pathologic findings by3groups of the size. ResultsConsistent with pathology,15cases were located in the pancreatic head,3cases were the neck,7cases were the body,4cases were the body and tail,9were the tail, and31cases were round/oval,7cases were lobulated/irregular.25cases with clear boundaries,24cases showed complete capsule and1case showed peripancreatic tissue invasion in pathology.13cases with unclear boundaries showed focal breakthrough capsule in pathology. Group A including5cases mostly showed homogeneous density/signal,1case with calcification on CT, and with homogeneously progressive enhancement. In relation to normal pancreatic parenchyma,5cases all appear hypodensity on dynamic contrast-enhanced CT images, and4cases appear iso/hyperintensity on dynamic contrast-enhanced MR images. Pathology showed the tumors were composed of a large amount of fibrous tissue. Group B including18cases mostly showed heterogeneous density/signal,6cases with calcification on CT,6cases with hemorrhage on MRI, and with solid part progressive enhancement. In relation to normal pancreatic parenchyma,18cases all appear hypodensity on dynamic contrast-enhanced CT images, and8cases appear iso/hyperintensity on dynamic contrast-enhanced MR images. Pathology showed tumor tissues were mainly mild bleeding, variable focal necrosis, with6cases of calcification. Group C including15cases showed more obvious heterogeneous density/signal, suggesting cystic change in different level,7cases with calcification on CT, and12cases with hemorrhage on MRI, and with solid part progressive enhancement. In relation to normal pancreatic parenchyma,15cases appear hypodensity on dynamic contrast-enhanced CT and MR images. Pathology showed variable focal splinter hemorrhage, necrosis with cystic change or with8cases of calcification. Conclusions①CT and MRI manifestations of SPTP have a close relation with pathology especially in the lesion size.②SPTP has its typical imaging features. Large SPTP is characterized by a well-encapsulated solid and cystic mass that demonstrates varying amounts of intratumoral hemorrhage and calcification with the solid part progressive enhancement. Small tumor has the features of homogeneous density/signal with progressive enhancement.③MRI is more powerful to identify the capsule, solid-cystic portions, hemorrhagic areas and progressive enhancement of SPTP, and CT is more powerful to identify calcification. Two imaging examination are supplement each other, and the characteristic imaging findings contribute to the diagnosis of the disease.