Insulinoma is a rare pancreatic neuroendocrine tumour that secretes insulin, causing hypoglycemia. Because of the nonspecific symptoms, the diagnosis could constitute a challenge. Early detection is important to prevent serious consequences.
A 31-year old woman was admitted for prolonged fasting test. She had no relevant past medical or surgical history till eight months before, when she had an episode of generalized tonic-clonic seizure with loss of consciousness. At this time, she was taken to emergency, with identification of a hypoglycaemia of 33 mg/dL. Unfortunately this was undervalued and she was discharged with an appointment on a neurologist. After evaluation, she did an EEG, which was normal, and blood tests that identified a fasting glycemia of 50 mg/dL. By recommendation of her general practitioner, she began to monitor her glycemia during the day, identifying multiple glycemia <50mg/dL – in fasting and post-prandial period. After the first generalized seizure, she had multiple seizures, always associated with hypoglycaemia. During the night she had to wake up every two hours to eat, in order to prevent hypoglycaemia. Moreover, in the last 6 months, she augmented 12 Kg. She also described two episodes of behavioural changes with confusion and speech alteration.
She wasn’t under any medication that could be associated with hypoglycemias. Previous records showed she had a fasting glycemia of 50 mg/dL two years ago. When she was admitted to our department, besides she had eat one hour before, she had glycemia <55 mg/dL. Blood tests showed glucose level=22 mg/dL, insulin=39 μU/mL (normal range 2.6-24.9 μU/mL), C-Pep=0.90 ng/mL (normal range 1.1-4-4 ng/mL). Plasma B-hydroxybutyrate was negative. After Glucagon EV, glucose level increase to 53 mg/dL (>25 mg/dL). We also evaluated cortisol and growth hormone that were normal. Abdominal computed tomography scan with contrast demonstrated a well-defined hypervascular lesion involving pancreas tail. Abdominal MRI was also performed showing a hypervascular lesion involving pancreas tail with 11x21mm. Laparoscopic surgery to enucleate the lesion was made. Pathological evaluation revealed a well-differentiated neuroendocrine tumour (positive staining for synaptophysin, cromogranin and insulin) measuring 0.3 cm. The diagnosis of pancreatic insulinoma was confirmed. After surgery, the glucose level increased to the normal range. The patient is currently in 6 months follow-up with a good evolution.
The diagnosis of insulinoma requires high suspicion. In this case, the patient didn’t have the typical insidious neurogenic symptoms. There is a need to value neuroglycopenic symptoms associated with hypoglycemia, otherwise serious consequences can occur.