Pancreatic hamartoma presenting with sleep-related behavioral abnormalities due to neuroglycopenia: a case report.

Pancreatic hamartoma (PH) is an exceedingly rare benign non-neoplastic lesion of the pancreas. Owing to its nonspecific clinical and radiological features, it is prone to misdiagnosis. Among its various subtypes, functionally active pancreatic hamartomas with distinct endocrine activity have only been sporadically reported in the literature as individual cases. We report the case of a 58-year-old female patient whose initial presentation was characterized by paroxysmal behavioral abnormalities during nocturnal sleep, manifesting as sudden agitation, arm-flinging, and purposeless stereotyped movements after sleep onset. During these episodes, the patient exhibited a confusional state with subsequent complete amnesia for the events, a clinical phenotype highly suggestive of REM sleep behavior disorder (RBD) or frontal lobe epilepsy. In-hospital monitoring revealed refractory nocturnal hypoglycemia. Imaging studies identified a mass in the pancreatic tail, and the patient underwent laparoscopic distal pancreatectomy. Postoperative histopathological and immunohistochemical examination confirmed the diagnosis of pancreatic hamartoma, composed predominantly of islet cells (approximately 90%) with associated islet cell tumor-like hyperplasia. Following surgery, the patient's nocturnal hypoglycemia and sleep-related behavioral abnormalities resolved completely.