Functional Insulinomas in a Rhesus Macaque (Macaca mulatta)

We report a rare case of functional insulinomas in a 16.7-year-old female Rhesus macaque (Macaca mulatta) that was presented with neuroglycopenic signs to the breeding colony hospital at the Tulane National Primate Research Center. At initial and follow-up examinations, the animal was consistently hypoglycaemic and was clinically maintained with additional fruits, other high-sugar food items and dextrose supplementation. Occasional episodes of seizure and collapse resolved quickly on administration of high-sugar food items. At nec-ropsy, the uncinate process of the pancreas had a 2.2 cm diameter, red, round, firm neoplastic mass, and another neoplasm was identified on histological examination of the head of pancreas. Histologically, neoplastic cells exhibited neuroendocrine packeting, resembled pancreatic islet cells and immunolabelled for chromogra-nin A, synaptophysin and insulin but not for somatostatin, gastrin or pancreatic polypeptide. A few cells im-munolabelled for glucagon. The clinical signs and gross and histological findings were consistent with functional insulinomas.(c) 2022 Elsevier Ltd. All rights reserved.