Endoscopic ultrasound-guided fine-needle aspiration for diagnosis of solid pseudopapillary tumors of the pancreas: A multicenter experience

Background and study aims: Solid pseudopapillary tumors of the pancreas are rare, low-grade, epithelial neoplasms that are usually discovered incidentally in young women. Distinguishing solid pseudopapillary tumors from other pancreatic tumors, especially pancreatic endocrine tumors, can be challenging. The role of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in this context remains unclear. The purpose of this study was to describe the endoscopic ultra-sound features of solid pseudopapillary tumors and the role of EUS-FNA in the preoperative diagnosis of these tumors. Patients and methods: Patients from five tertiary referral centers with surgically confirmed solid pseudopapillary tumors who had undergone preoperative EUS-FNA were included. The endoscopic ultrasound findings, cytologic descriptions, immunostaining results, operative records, surgical pathology, and results of the most recent clinical follow-up were reviewed. Results: A total of 28 patients were identified (four men [14%], 24 women [86%], mean age ± standard deviation [SD] 35±10 years). Solid pseudopapillary tumors had been found as incidental findings on cross-sectional imaging in 50% of cases. The mean tumor size±SD was 42 ± 19.5 mm and the majority were located in the pancreatic body and tail. The endoscopic ultrasound report described a well-defined, echo-poor mass in 86%; the tumors were solid in 14 patients (50%), mixed solid and cystic in 11 patients (39 %), and cystic in three patients (11 %). A preoperative diagnosis of solid pseudopapillary tumor was made in 21 patients (75 %) on the basis of EUS-FNA cytology. Surgical resection was performed in all cases. Laparoscopic resection was performed in eight of these patients (29 %). Conclusions: A solid pseudopapillary tumor should be included in the differential diagnosis of any well-demarcated, echo-poor, solid or mixed solid/cystic pancreatic lesion seen during endoscopic ultrasound, particularly in young women. The diagnostic accuracy of EUS-FNA for solid pseudopapillary tumors was 75% in this study. A definitive preoperative diagnosis can guide the surgical approach in selected cases.