Non-Islet Cell Tumor Hypoglycemia (NICTH) Associated with a Gastric Leiomyoma Presumably Producing Igf-2 in a Dog Documented by Continuous Glucose Monitoring

Abstract

Hypoglycemia in dogs is a clinically relevant metabolic disturbance that may be associated with endocrine disorders, systemic diseases, or neoplastic processes. Although pancreatic insulinoma represents the most frequent neoplastic cause, some extrapancreatic tumors may induce hypoglycemia through paraneoplastic mechanisms known as non-islet cell tumor hypoglycemia (NICTH). We describe the case of a geriatric Poodle bitch with recurrent episodes of weakness, collapse, incoordination, tremors, and transient visual disturbances. Persistent hypoglycemia was documented through serial biochemical analyses and continuous interstitial glucose monitoring, with multiple hypoglycemic episodes and nadir values close to 40 mg/dL. Abdominal imaging studies identified a mass located in the cranial abdomen, initially of uncertain anatomical origin. Because serum insulin concentrations were within normal to low ranges and imaging did not confirm a pancreatic origin, the possibility of an extrapancreatic tumor associated with NICTH was considered from the initial diagnostic approach. Given the limited availability of direct Big IGF-2 measurement in veterinary medicine, IGF-1 was assessed as an indirect marker of the GH–IGF axis, revealing a marked decrease. During exploratory laparotomy, a well-demarcated mass originating from the gastric antral region was identified, measuring approximately 8.5 cm in its largest axis and weighing an estimated 350 g, and was completely resected. Histopathological analysis confirmed the diagnosis of gastric leiomyoma. Following tumor resection, normalization of blood glucose concentrations and complete resolution of clinical signs were observed. Overall, clinical, endocrinological, imaging, surgical, and histopathological findings support a presumptive diagnosis of IGF-2–mediated NICTH. This case highlights the importance of considering extrapancreatic tumors in the differential diagnosis of persistent hypoglycemia in dogs and demonstrates the utility of continuous glucose monitoring to document the frequency and severity of hypoglycemic episodes.