Abstract
Objective Insulinoma is a rare tumor of the pancreas that can lead to
spontaneous hypoglycemia due to excessive insulin secretion. Seventy-two-hour
fast is the gold standard for finding the correct diagnosis. Endoscopic
ultrasound (EUS) is an established examination method to identify the
suspicious lesion. Previous studies correlate the measured size of insulinoma
and their endocrine behavior. This study was designed to find a relation between
these variables.
Methods We took the data of patients who had a histologically confirmed
insulinoma after receiving an endoscopic ultrasound in our department. Size and
echogenicity were correlated with the endpoint of the 72-hour fast and hormone
levels.
Results A total of 45 patients were identified. Most insulinomas were
small with a volume of<2 cm3 (median 1.15 cm3).
There was no correlation between the duration of fasting, hormone levels, and
the size of the insulinoma. In addition, in a subgroup analysis, no connection
could be established between the size of the insulinoma and the amount of
insulin released after oral glucose exposure. We found that homogeneous tumors
were significantly smaller and had a lower Ki-67 index. Furthermore, there was a
tendency towards a shorter duration for the 72-hour fast for the small
tumors.
Discussion This data suggests that the measured size of insulinoma by EUS
is not related to the time until termination of the 72-hour fast and measured
hormone levels. The echogenicity seems more important, showing that homogenous
tumors are an indicator of a higher differentiation, which can result in a
shorter duration of the fasting period. The differences in the secretion
behavior of the insulinomas could complicate the correlation of size and the
72-hour fast period.
Key words
insulinoma - insulin - endoscopic ultrasound - imaging - 72-hour fast - hypoglycemia - tumor size
