Prediction of Recurrence Risk in Solid Pseudopapillary Neoplasm of the Pancreas: Single-Institution Experience

Background: Solid pseudopapillary neoplasm (SPN) of the pancreas is a low-grade malignant neoplasm with unpredictable behavior. Factors associated with recurrence were not conclusively identified. The aim of this study is to define the clinicopathological criteria for recurrence risk prediction in SPNs based on the most recent scientific evidence and to present our experience with SPNs. Methods: A retrospective review of patients with SPNs operated on in our institution from June 2012 to June 2018 was completed. Patient characteristics and clinical outcomes were analyzed. A detailed literature review was performed to evaluate the factors associated with the recurrence of SPNs. Results: The cohort consisted of 13 female patients with a median age of 24 years and a mean tumor size of 7.7 cm. Body and tail (53.8%) were the most common location, and distal pancreatectomy with splenectomy was the prevalent surgical procedure. One patient of SPN operated on for local recurrence after 11 years which had high-grade malignant histological features on the previously resected tumor. At a median follow-up of 42 months (range 36 to 108), all patients were disease free and alive. The proposed criteria for predicting recurrence in SPNs include tumor size >8 cm, synchronous metastasis, malignant SPN (according to 2000 or 2010 World Health Organization [WHO] criteria), lymphovascular invasion, pancreatic parenchymal invasion, and high Ki-67 index (>4%). All these are worse prognostic factors and should be considered as high-risk factors for postoperative relapse. Conclusion: The above-mentioned criteria can better predict SPN recurrence. Patients with high-risk features should undergo an extended follow-up.