Solid Pseudopapillary Tumors of the Pancreas: Specific Pathological Features Predict the Likelihood of Postoperative Recurrence

Background: Since their introduction in the WHO classification, the incidence of solid pseudopapillary tumors (SPTs) of the pancreas has progressively increased, mainly because of the widespread use of cross-sectional imaging. Few recent studies have analyzed the biological behavior of SPTs, but reliable data on long-term follow-up are needed. Methods: Retrospective analysis of two Institutions with high caseload, The Department of General Surgery-Pancreas Institute, University of Verona Hospital Trust and the Department of General Surgery, Massachusetts General Hospital, Harvard Medical School, was carried out. Data from 131 consecutive resections for SPT performed during the last three decades were collected and analyzed. Results: The majority of patients were female (86.3%) with a median age of 33 (7-68) years. The prevalent location was the pancreatic tail (33.5%). Applying the WHO criteria, 16 (12.2%) SPTs were considered malignant due to the presence of at least pancreatic parenchyma (9.9%), perineural (4.6%), and/or angiovascular invasion (2.3%). After a median of 62 months after surgery, only two patients had a recurrence (1.5%). Both of them fulfilled the WHO criteria for malignant SPT (vs. 10.7% of those who did not recur, P = 0.01), had an infiltrative growth pattern (vs. 10.8%, P = 0.01), pancreatic parenchyma invasion (vs. 9.7%, P = 0.01) and capsular invasion (vs. 4.9%, P = 0.004). Conclusion: Overall, SPTs are associated with excellent survival results after surgical resection. Disease recurrence is extremely rare, and might occur if the primary tumor presents with either pancreatic parenchyma or capsule invasion. (C) 2016 Wiley Periodicals, Inc.