Endocrine Abstracts

Introduction: Insulinoma is a rare pancreatic endocrine tumor derived from ß cells that secret insulin, which results in hypoglycemia. Most are benign and solitary. The median age at diagnosis is about 47 years. The age range for peak incidence is between 30 and 60 years and it is more prevalent in women. Diagnosis relies on clinical features along with laboratory tests and imaging. However, the nonspecific symptoms and small size of these tumors can lead to difficulties of diagnosis and localization.

Case report: An 84 years old man was admitted to the emergency department with seizures and severe hypoglycemia (44 mg/dl). The patient have had a previous history of fatigue, dizziness and tremors since the past two years, diagnosed as Parkinson’s disease. 72 hour fast test showed increased levels of insulin (7.1 mUI/ml), C-peptide (2.21 ng/ml) and pro-insulin (51.7 pmol/l). Screening for sulfonylurea, anti-insulin antibodies and anti-insulin receptor antibodies was negative.

MEN 1 syndrome was excluded. The abdominal CT scan revealed a 12 mm nodule in the uncinate process of the pancreas. Endoscopic ultrasonography was performed and biopsy was suggestive of a neuroendocrine tumor.

The patient was discharged in euglycemia, under diazoxide and poli-fractionated diet, pending surgical decision.

Surgical resection was performed and histopathology was consistent with the diagnosis of benign insulinoma. The clinical course was favourable, with regression of symptoms without diazoxide.

Conclusion: Insulinoma remains a diagnostic challenge since symptoms are nonspecific and may lead to incorrect diagnosis. As in this clinical case, a neurologic disease might be considered the culprit.

We discuss the importance of considering the diagnosis, since it is easily confirmed by standard endocrine tests and can be potentially curable through surgical resection. On the other hand severe and sustained hypoglycemia can lead to disability and death.