Multicenter Study on the Performance of Imaging Tests Compared to Endosonography-Guided Fine-Needle Aspiration in the Diagnosis of Solid Pseudopapillary Neoplasms of the Pancreas.

Introduction: Imaging diagnosis of pancreatic solid-pseudopapillary neoplasms (SPNs) is difficult. Preoperative diagnosis by endosonography-guided fine-needle aspiration (EUS-FNA) is possible and has been reported in the literature in pancreatic tumors. However, its usefulness is still controversial. The aim of this study was to determine the accuracy of the EUS-FNA in the diagnosis of patients with SPN and describe the findings in computerized tomography (CT), magnetic resonance cholangiopancreatography imaging (MRI/MRCP), and EUS therefore comparing the imaging methods alone to the findings of microhistology (McH) obtained by EUS-FNA. Materials and Methods: We retrospectively reviewed the medical records of patients undergoing EUS-FNA with suspected SPN in imaging studies in 5 Brazilian high-volume hospitals (two university hospitals and three private hospitals). The demographic data; findings in CT, MRI/MRCP, and EUS; and McH results obtained by EUS-FNA were noted prospectively. The final diagnosis was obtained after the anatomopathological examination of the surgical specimen in all patients (gold standard), and we compared the results of CT, MRI/MRCP, EUS, and the McH with the gold standard. Results: Fifty-four patients were included in the study, of which 49 (90.7%) were women with an average age of 33.4 (range 11-78) years. The most common symptom presented was abdominal pain, present in 35.2% patients. SPN was detected incidentally in 32 (59%) patients. The average size of the tumors was 3.8 cm (SD: 2.26). The most common finding at EUS was a solid, solid/cystic, and cystic lesion in 52.9%, 41.1%, and 7.8% patients, respectively. The final diagnosis was 51 patients with SPN and 3 with nonfunctioning pancreatic neuroendocrine tumors (NF-NET). The correct diagnosis was made by CT, MRI/MRCP, EUS isolated, and EUS-FNA in 21.9%, 28.88%, 64.71%, and 88.24%, respectively. EUS-FNA associated with CT and MRI increased diagnostic performance from 22.72% to 94.11% and from 29.16% to 94.11%, respectively. Conclusions: SPN are rare, incidentally identified in most cases, and affect young women. Differential diagnosis between SPN, NF-NET, and other types of tumors with imaging tests can be difficult. EUS-FNA increases preoperative diagnosis in case of diagnostic doubt and should be used whenever necessary to rule out NF-NET or other type of solid/cystic nodular lesion of the pancreas.