Insulinoma

Ray Ballinger, MD, PhD

Straub Clinic and Hospital

rballinger at straub.net

Abstract

27 y/o woman

Keywords

CT MRI abdomen


Publication Date: 18 March 2004
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History and Images

27 y/o woman 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.

pre-contrast CTpost-contrast CTAxial T2-weighted MRCoronal T2-weighted MR
Catheter in R hepatic veinCatheter in splenic arteryCatheter in hepatic arteryCatheter in SMA

Findings

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 assessory 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 a different times into the splenic, hepatic and superior mesenteric artery with sampling from the right hepatic vein for insulin levels several times over two minutes each.

Diagnosis

Insulinoma

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.

Discussion

Insulinomas 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 imaging. On MRI they tend to be bright on T2-weighted sequences and low-density on T1- weighted sequences.