Abstract
Background and Study Aims: The correct localization of insulinomas using endoscopic ultrasonography (EUS) has
been reported to be as high as 80 % in multicenter patient cohorts.
Patients and Methods: Over 24 months, we prospectively investigated 14 patients (11 women, three men) with
a definite biochemical diagnosis of endogenous hyperinsulinism prior to surgical exploration
and removal of an insulinoma. The endoscopic invesigator was not aware of any other
imaging results if they had been performed in referring hospitals.
Results: The overall sensitivity of EUS in the detection of pancreatic insulinomas was 57 %
(eight of 14 tumors); the sensitivity for insulinomas in the head of the pancreas
was 83 % (five of six); and 37 % (three of eight) for tumors in the tail of the pancreas.
The actual median diameter of undetected tumors was 11 × 9.5 mm, the median volume
0.66 ml (range 0.13-2.6 ml). The median diameter of correctly detected tumors was
16 × 11 mm, the median volume 1.37 ml (range 0.7-6.3 ml), the differences not being
significantly different. In two patiens, false-positive results were caused by peripancreatic
lymph nodes.
Conclusions: The sensitivity of EUS in the detection of pancreatic insulinomas depends on the
location of the tumor, and possibly on the size of the tumors. Tumors not detected
by EUS were likely to be smaller than detected tumors, and were likely to be located
in the tail of the pancreas.
