Introduction:
Insulinomas are rare functioning neuroendocrine (NEN) tumors with an
annual incidence of 1-4 cases per million. Up to 10% of insulinomas are
associated with multiple endocrine neoplasia 1 (MEN1). Most of the
tumors present with symptomatic hypoglycemia and the diagnosis is
established by demonstrating endogenous hyperinsulinemia in the presence
of hypoglycemia(1). Several non-invasive techniques are used to localize
the lesion and include an ultrasound (US) abdomen, CT scan, MRI, and
molecular imaging techniques like NM 18F-DOPA whole-body PET CT and
Ga-68 DOTATATE scan(2-4). Due to the low sensitivity of the non-invasive
methods, the localization of the tumor presents a diagnostic challenge,
and invasive techniques like endoscopic ultrasound (EUS) and angiography
and arterial stimulation venous sampling (ASVS) should be used if the
suspicion is high(5, 6). We present a case of insulinoma presenting with
seizure episodes. Laboratory testing revealed evidence of hyperglycemia,
but all the non-invasive testing, including molecular imaging, was
negative, and the diagnosis was established after localizing and
fine-needle aspiration (FNA) of the tumor with EUS