Background: Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous group of islet cell-derived neoplasms with a propensity toward hormone production. Among PNETs, proinsulin-secreting tumors (proinsulinomas) are exceedingly rare. The objective of this study is to collect and summarize the existing literature to provide a comprehensive evaluation of this uncommon disease.
Methods: A systematic review was performed to characterize the clinicopathologic features of proinsulinoma. Using the electronic biomedical databases PubMed, Ovid Medline, and Embase, 316 publications were screened for relevance of which 14 were selected. We also present two patients with proinsulinoma treated at Yale New Haven Hospital.
Results: Of the 16 patients included in the study, the mean age was 56.8 and there was a 2:1 female predominance. The majority of patients presented with symptomatic hypoglycemia with normal or low insulin levels. Median tumor diameter was 1.2 cm and 80% were located in the body and tail of the pancreas. Following resection, most patients had normalization of hormonal levels without recurrence (75%; 12/16).
Conclusion: Proinsulinomas are rare pancreatic neuroendocrine tumors that have the potential to cause hypoglycemia. While insulinomas and proinsulin-secreting tumors have many physiologic parallels, these cases illustrate several key distinctions in their diagnosis and management.
Keywords: Neuroendocrine tumor; Pancreas; Proinsulin.