Insulinoma Masquerading as Transient Neurocognitive Impairment

      A 55-year-old man presented with 6 months of increasingly frequent episodes of confusion and abnormal behavior (Video 1). Neurologic examination and diagnostic work-up were unremarkable. He was evaluated for stroke, Huntington's disease, conversion disorder, and other neuropsychiatric conditions without a satisfactory diagnosis. Months later, he suffered another episode and was found to have a glucose of 33 mg/dL. This improved with glucose administration but rapidly dropped to 30 mg/dL. A 72-hour fast, which revealed a low serum glucose and elevated insulin, pro-insulin, and C-peptide levels, strongly suggested the diagnosis of insulinoma. Contrast computed tomography (CT) revealed a suspicious pancreatic mass (Figure 1), and endoscopic ultrasound-guided fine needle aspiration confirmed the diagnosis. The patient was cured of his symptoms following distal pancreatectomy (Figure 2).
      Fig 1
      Figure 1Contrast abdominal computed tomography scan with pancreas protocol demonstrating an arterial enhancing 1.6×1.2-cm mass in the pancreatic tail, consistent with insulinoma.
      Fig 2
      Figure 2Resection of 8 cm of the distal pancreatic tail, cut in cross-section to reveal a well-circumscribed 1.3×1.0-cm insulinoma.
      Fig 3
      Video 1Demonstration of the patient during an episode of hypoglycemia presenting with neuroglycopenic symptoms.
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