Presented 3 days after a 20 minute episode of dizziness, blurred vision and weakness. A non-fasting blood glucose level of 45 mg/dL was discovered.
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The three CT images were obtained pre-contrast, arterial phase and portal phase. The arterial phase shows a subtle enhancing mass in the tail of the pancreas measuring about 2 cm in diameter. The MRI T2-weighted fat suppressed images show the mass in the tail of the pancreas to be of increased signal compared to the remainder of the pancreas. An incidental accessory spleen is noted in the splenic hilum cephalad to the tail of the pancreas.
Calcium arterial stimulation with venous sampling was performed to confirm the localization of the insulinoma in the tail of the pancreas. A calcium solution was injected at different times into the splenic, hepatic and superior mesenteric arteries with sampling from the right hepatic vein for insulin levels several times over two minutes each.
At surgery a 2.2 x 1.7 x 1.3 cm diameter nodule was removed, which at pathology showed a pseudoencapsulated tumor composed of islet cells with a benign appearance.
Insulinomas are neuroendocrine tumors that arise from B-type islet cells in the pancreas and are rarely larger than 2 cm in diameter. Patients present with CNS and vasomotor symptoms resulting from spontaneous hypoglycemia. Insulinomas are hypervascular and so are dense on enhanced CT. On MRI they tend to be bright on T2-weighted sequences and low-density on T1- weighted sequences.
Other neuroendocrine tumors found in the pancreas include:
- 1. Druce MR, Muthuppalaniappan VM, O'Leary B et-al. Diagnosis and localisation of insulinoma: the value of modern magnetic resonance imaging in conjunction with calcium stimulation catheterisation. Eur. J. Endocrinol. 2010;162 (5): 971-8. Eur. J. Endocrinol. (full text) - doi:10.1530/EJE-10-0056 - Pubmed citation
- 2. ÖBerg K, Knigge U, Kwekkeboom D et-al. Neuroendocrine gastro-entero-pancreatic tumors: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann. Oncol. 2012;23 Suppl 7 (suppl 7): vii124-30. Ann. Oncol. (full text) - doi:10.1093/annonc/mds295 - Pubmed citation