A 56-year-old man was referred with asymptomatic elevation of
pancreatic hydrolase levels. Magnetic resonance imaging (MRI) delineated a
pancreatic lesion with a low T1 and high T2 signal ([Fig. 1]).
Fig. 1 Endoscopic ultrasound
shows an oval, well-defined, isoechogenic, homogeneous, 14-mm mass located in
the pancreatic tail. There is no cystic component or calcification (SA, splenic
artery; SV, splenic vein).
Endoscopic ultrasound (EUS) found an oval, well-defined,
isoechogenic, homogeneous mass in the pancreatic parenchyma, without any
vascular invasion and no locoregional lymph nodes ([Fig. 2]).
Fig. 2 Axial coregistration of
turbo spin echo (TSE) T2-weighted and diffusion-weighted sections shows a
well-defined and very bright nodule in the tail of the pancreas (arrow).
Fine-needle aspiration (FNA) showed small epithelioid cells.
Immunostaining was positive for antichromogranin, antisynaptophysin, and
anti-KI-67 (5 %), and a few cells were positive for anti-CD56.
This was consistent with a neuroendocrine tumor (NET).
Octreotide positron emission tomography combined with computed
tomography (PET-CT) showed a focal uptake into the pancreas without any other
nonphysiological uptake ([Fig. 3]).
Fig. 3 Octreotide positron
emission tomography combined with computed tomography (PET-CT) showing focal
uptake in the pancreatic tail (arrow) suggestive of neuroendocrine tumor.
CA19 – 9 and chromogranin levels were
normal.
Caudal pancreatectomy with spleen preservation was performed.
Histological examination found no proof of NET but did reveal an
intrapancreatic accessory spleen (IPAS) ([Fig. 4]). The postoperative period and follow-up were
satisfactory.
Fig. 4 Histological image
(hematoxylin and eosin [H&E] staining) of the intrapancreatic
splenic tissue.
Accessory spleens may be found in 15 % of the
population but are rarely located in the pancreatic tail (17 %)
[1]. Most IPASs have a homogeneous contrast-enhanced
appearance on CT and MRI, sharing features with hypervascular lesions (such as
NETs) [1].
Octreotide scans have a high sensitivity for detection of
gastrointestinal NET
(70 % – 95 %). The somatostatin
receptors on the surface of splenic lymphocytes may lead to false diagnosis of
NET [2]. Nuclear scintigraphic investigations such as
those with 99mTc sulfur colloid can help in identifying IPAS
[3].
EUS findings include regular margins and homogeneous echogenicity,
ranging from hypoechoic to hyperechoic [4].
FNA reveals small lymphocytes and a mixed inflammatory infiltrate
with the appearance of white pulp. Sampling of islet cell clusters from the
adjacent pancreatic parenchyma can lead to misdiagnosis. CD8 immunostaining of
splenic sinus endothelial cells can help in confirming the diagnosis, as done
retrospectively on FNA material in our patient [5].
Ultrasound endoscopists should be aware of this entity (IPAS) in
order to avoid unnecessary surgery, even when FNA shows cells with NET
characteristics.
Endoscopy_UCTN_Code_CCL_1AF_2AG_3AB
