PMC5700780_01
Magnetic resonance imaging without contrast, showing an advanced picture of hepatorenal polycystic disease.
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On suspicion of insulinoma, abdominal US was performed, which showed the known polycystic kidney and liver disease; however, no pancreatic mass was found, even on subsequent MRI (performed without contrast media, owing to CKD) which better characterized the hepatorenal polycystic disease (Figure 1).
(A) Endoscopic ultrasound image of a small isoechogenic nodule (arrow) in the pancreas head, adjacent to the gastro-duodenal artery (arrow head) deemed suspect for neuroendocrine tumor but not confirmed by histological evaluation. (B) Intraoperative ultrasonography showing a small hypoechogenic nodule (arrow) in the uncinate process of the pancreas; this proved to be an insulinoma on combined histologic and immunohistochemical evaluation.
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By contrast, EUS revealed a 1-cm isoechogenic nodule in the superior part of the pancreatic head and adjacent to the gastro-duodenal artery, which was deemed suspect for neuroendocrine tumor (NET) (Figure 2A). During surgery, continuous 5% glucose and somatostatin (to reduce insulin secretion) infusion was performed, and the nodule observed during EUS in the superior part of the pancreatic head was found, as was another nodule in the uncinate process (1.5 cm maximum diameter); this latter was hypoechogenic on IOUS (Figure 2B).
68Gallium DOTA-Tyr3-octreotide positron emission tomography/computed tomography revealed intense uptake (standardized uptake value max: 16) by a small region of the pancreatic head (arrow) where the insulinoma was subsequently located during surgery by means of intraoperative ultrasonography and removed.
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Fine-needle aspiration (FNA) of the suspect nodule was deemed too risky. 68Gallium DOTA-Tyr3-octreotide (DOTATOC) PET/CT showed an intense uptake (SUV max: 16) by a small region of the pancreatic head (Figure 3).
(A) The nodule removed from the uncinate process of the pancreas featured trabecular-insular architecture with cubic/polygonal cells, sparsely granulated cytoplasm, and round and slightly dysmetric nuclei (hematoxylin-eosin, x20). (B) Immunohistochemistry showed faint homogeneous cytoplasmatic positivity for insulin (3,3'-diaminobenzidine staining, x20). (C) Ki-67% labeling index of the tumor cells was low: 1% (arrow, x20). A final diagnosis of well-differentiated (G1) insulinoma was made.
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Final histology showed normal pancreatic tissue in the nodule from the pancreatic head, whereas the nodule in the uncinate process proved to be an insulinoma on combined histologic and immunohistochemical evaluation (Figure 4A to C).