A Case of Nonislet Cell Tumor Hypoglycemia Due to Metastatic Salivary Myoepithelial Carcinoma

Abstract

Background/Objective: Nonislet cell tumor hypoglycemia (NICTH) is an uncommon cause of hypoglycemia due to a relative surplus of insulin-like growth factor 2 (IGF-2) or its precursor molecule. The diagnosis is confirmed by an elevated ratio of IGF-2 to insulin-like growth factor 1 (IGF-1). Myoepithelial carcinoma (MECA) is a rare and aggressive salivary gland cancer that has not been previously associated with NICTH. Case Report: A 63-year-old female with a past medical history of metastatic salivary MECA, type 2 diabetes mellitus previously on metformin, hypertension, and hypothyroidism presented to her oncologist for chemotherapy and was found to have a serum glucose of 30 mg/dL (reference: 65-99). She was admitted for further diagnostic work-up which revealed an insulin level of <1 μU/mL (reference: 3-25), C-peptide <0.5 ng/mL (reference: 1.1-4.3), IGF-1 of 15 ng/mL (reference: 41-279), and IGF-2 of 147 ng/mL (reference: 180-580) with an IGF-2:IGF-1 molar ratio of 10, consistent with NICTH. The patient’s hypoglycemia unfortunately was quite resistant to treatment, requiring a combination of corticosteroids, continuous dextrose infusion, and somatostatin injections. The patient died 3 weeks after presenting with hypoglycemia. Discussion: Salivary MRCAs commonly contain pleomorphic adenoma gene 1 oncogene rearrangements which are associated with increased IGF-2 production and may predispose patients to hypoglycemia. Conclusion: This case demonstrates that NICTH can be associated with metastatic salivary MECA. The hypoglycemia in this scenario is challenging to manage and is associated with poor prognosis.

Keywords

• nonislet cell tumor hypoglycemia
• insulin-like growth factor-2
• salivary myoepithelial carcinoma
• corticosteroids