Insulinoma Manifesting Early Postpartum: Case Report and Review of the Literature

ABSTRACT Objective: Insulinomas are insulin-producing neuroendocrine tumors. Insulinomas presenting during pregnancy and the early postpartum period are very rare. Methods: A 33-year-old woman with hypoglycemia early postpartum is described. Abdominal computed tomography and endoscopic ultrasound showed 2 lesions of the pancreas. An 11C-5-hydroxy-l-tryptophan (11CHTP) positron emission tomography-computed tomography (PET-CT) scan demonstrated additional uptake in lymph nodes and liver, suggesting malignant insulinoma. Six months after pylorus-preserving pancreatoduodenectomy and excision of liver and lymph node metastases, tumor progression was noted on repeated 11C-HTP PET-CT scans without recurrent hypoglycemia. She was enrolled in a clinical trial and was randomized for dual pan-class I phosphoinositide 3-kinase inhibitor and mammalian target of rapamycin inhibitor treatment, on which there was no tumor progression during 21 months follow-up. A systematic search of PubMed and Medline with the search strategy ‘insulinoma AND pregnancy’ OR ‘insulinoma AND postpartum’ was performed to identify English-, Dutch-, and German-language publications. All publications about (malignant) insulinoma during pregnancy and in the early postpartum period (≤3 months postpartum) were reviewed in addition to the described case report. Results: Insulinoma manifesting during pregnancy or early after delivery has been described in 31 cases, including only 3 cases of malignant insulinoma. Management of malignant insulinoma requires an individualized approach; optimal medical treatment is evolving. Conclusion: The usefulness of 11C-HTP PET-CT in the diagnosis of malignant insulinoma was demonstrated in the present case. Hypoglycemia may particularly become manifest in the postpartum period when insulin action increases consequent to decreased levels of placenta-derived counterregulatory hormones after delivery. Abbreviations: 11C-HTTP 11C-5-hydroxy-l-tryptophan CT computed tomography EUS endoscopic ultrasound MEN-1 multiple endocrine neoplasia type 1 mTOR mammalian target of rapamycin MRI magnetic resonance imaging PET-CT positron emission tomography-computed tomography SRS somatostatin-receptor scintigraphy