An insulinoma is an insulin-secreting neuroendocrine tumor (NET)
which may lead to symptomatic fasting hypoglycemia. These often small lesions
are primarily located in the pancreas. Endoscopic ultrasonography (EUS) has
been found to be the optimal diagnostic modality for NET identification.
Surgical resection of the tumor is the mainstay of therapy for an
insulinoma. However, for a small subset of patients, particularly those who are
elderly with comorbidity, pancreatic surgery can be associated with high
morbidity and mortality rates. It has been suggested that minimally invasive
EUS-guided ablative treatment may be an attractive alternative therapy for
these patients [1]
[2].
An 82-year-old woman with a history of heart failure presented with
symptomatic hypoglycemia (glucose 2.2 mmol/L) and elevated levels of
blood insulin (14 mIU/L) and C-peptide (1820 pmol/L). A computed
tomography (CT) scan of the pancreas revealed no lesion. Linear-array EUS
showed a round, well-demarcated, hypoechoic lesion of
9.5 × 8.0 mm in the pancreatic body, near the
confluence of the superior mesenteric and splenic veins ([Fig. 1]). The results of cytological investigation
using EUS-guided fine-needle aspiration (EUS-FNA) were compatible with a NET
([Fig. 2]).
Surgical resection was considered to be associated with a high risk
of complications. Instead, we decided to inject the lesion with 0.3 ml
of ethanol (96 %) under EUS guidance using a 25-gauge needle
(EchoTip Ultra; Cook, Limerick, Ireland) through a linear-array echoendoscope
(GF-UCT140-AL5; Olympus, Tokyo, Japan). The lesion became a whitish color
during ethanol injection ([Video 1]).
Directly after the ethanol injection, blood glucose
(6.4 mmol/L), insulin (6 mIU/L), and C-peptide
(910 pmol/L) levels all normalized. No abdominal pain occurred, and
serum amylase and lipase levels remained normal. After 2 months, EUS showed a
decrease in the diameter of the lesion
(7.0 × 5.5 mm). The lesion appeared somewhat more
hypoechoic than before, and the borders were less well demarcated ([Fig. 3]). Over a period of 6 months, the patient
remained without any symptoms of hypoglycemia.
Fig. 1 A round,
well-demarcated, hypoechoic lesion of 9.5 × 8.0 mm
in the pancreatic body, highly suggestive of a neuroendocrine tumor (NET).
Fig. 2 Cytology smear after
endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA), showing a
cellular specimen composed of a loosely arranged monotonous cell population of
plasmacytoid cells with eccentric nuclei (arrow) and formation of rosettes
(circle), consistent with a neuroendocrine tumor (NET).
Fig. 3 The pancreatic lesion, 2
months after ethanol (96 %) ablation therapy.
Video
1 The neuroendocrine tumor
(NET) was punctured with a 25-gauge endoscopic ultrasonography (EUS) needle
through a linear-array echoendoscope. A volume of 0.3 ml ethanol was
injected. During injection, a whitish blush was seen in the lesion.
Endoscopy_UCTN_Code_TTT_1AS_2AD
