Pancreatic Neuroendocrine Tumors Complicated by Sinistral Portal Hypertension: Insights into Pathogenesis.

Purpose: To investigate the association between pancreatic neuroendocrine tumors (panNETs) and sinistral portal hypertension (SPH) and provide insights into the pathogenesis. Methods: A retrospective review of panNETs was conducted from our institution for 12 years. Medical imaging findings were analyzed to determine any association with splenic vein thrombosis (SVT) at diagnosis. The cases were further selected based on the criteria for SPH, namely, (1) presence of SVT, (2) gastric varices, (3) patent portal vein, and (4) normal liver function tests. Results: There were 61 patients with panNETs and 8 (8/61) had SVT and gastric varices at diagnosis. Four (4/8) met the strict criteria for SPH while the other four had more conventional portal hypertension. The four with SPH had large tumors located in the tail with splenic vein invasion and three of four presented with bleeding gastric varices. All four patients underwent surgical resection. Mean follow-up was 8.5 years and the hematemesis never recurred. The other four patients (four of eight) with gastric varices had unresectable disease and all died after a mean survival of 29 months. Conclusion: PanNETs appear to be more commonly associated with SVT and SPH compared with other tumors. This could be related to their relatively indolent nature and their intrinsic vascularity. From a surgical viewpoint, the decision to operate depends on many factors including but not limited to the size/stage, grade, and functionality of the tumor and comorbidities. These considerations notwithstanding, the association between panNETs and SPH suggests that there is benefit in timely resection of panNETs located in the tail.