Introduction
Pancreatic neuroendocrine tumors are a subset of Neuroendocrine tumors
(NET) that mainly originate from the neuroendocrine system. They account
for less than 10% of total NETs and have a general incidence of 0.5 per
100,000 persons per year [1]. Only 10 to 30% of these tumors are
hormone-secreting, with the majority being insulinomas. The tumors are
often found incidentally in the pancreas or GI system on imaging.
Pathological specimens are generally positive for Chromogranin A and
Synaptophysin but can additionally be positive for other serum markers
such as Insulin, Gastrin, and VIP, depending on the subtype of NET
[2]. General management includes surgery for localized disease and
surgery/chemotherapy in combination for extensive disease. Prognosis is
poor for those with liver metastases, with an overall mortality rate
greater than > 80%. Functional tumors are generally
localized and rarely present as metastatic disease [3].
Among functional NETs, Insulinomas are the most common. Incidence is
around 1 to 3 cases per million and is usually present in the pancreas
over 99% of the time [4]. Diagnosis is established with symptomatic
hypoglycemia in the setting of elevated insulin and c-peptide levels
after a 72-hour fasting test. Blood glucose levels usually improve with
Glucagon or Dextrose administration. These lesions are amenable to
treatments such as alcohol ablation, radiofrequency ablation,
embolization, or surgical resection. Surgical resection is the preferred
option for isolated lesions as it is often curative [5]. Symptomatic
management of hypoglycemia involves dextrose administration and
Diazoxide. Diazoxide inhibits the release of insulin from insulinoma
cells and is often the only effective measure prior to surgery [6].
Somatostatin analogs such as octreotide are also used in combination
with diazoxide in more severe cases but can lead to episodes of
hypoglycemia [7]. Cases involving surgical management have a good
prognosis [6,7].
Malignant insulinomas only account for about 5% of all insulinomas at
presentation [8,9]. In patients with distant metastases, surgical
resection with lymph node dissection improves prognosis. However, the
overall difference is minimal, and the data is limited in these cases
[10]. Overall, these patients do quite poorly due to limited
treatment options. There are very few case reports that discuss the
conversion of non-functional metastatic NET into a malignant insulinoma.
This case report presents such a conversion in an elderly female
patient.