Objective: gastroenteropancreatic (GEP) neuroendocrine tumors, suspected on clinical basis, are often difficult to localize. We report our experience with endoscopic ultrasonography (EUS) in the preoperative localization of pancreatic endocrine tumors (PETs), compared to other imaging modalities, and in staging and following up carcinoid tumors (CTs) of the gastrointestinal (GI) wall.
Methods: 50 patients (20 males; mean age 54 years), 39 with suspected PETs and 11 with GI CTs underwent EUS (Olympus GF-UM2 or GF-UM3). EUS data could be compared with resected specimens in 25 out of the 39 PETs and five out of the 11 CTs.
Results: in the PETs group 42 tumors (35<20 mm) were removed: 23 in the pancreas, eight in the duodenum, and 11 in the lymph nodes. EUS correctly localized 20 out of the 23 (87%) pancreatic tumors, included 11 out of the 12 (91.6%) insulinomas, three out of the eight (37.5%) duodenal gastrinomas, and ten out of the 11 (90.9%) metastatic lymph nodes. Furthermore EUS accurately evaluated the depth of parietal invasion of CTs in three out of four patients (75%) (two after and one prior to endoscopic resection). In three patients EUS was confirmed as normal on resected specimens (two pancreas and one stomach). In the PETs group, a correct localization was obtained by ultrasonography (US) only in 17.4% of cases, by computed tomography (CT) in 30.4%, by magnetic resonance imaging (MRI) in 25%, by angiography in 26.6%, and by somatostatin receptor scintigraphy in 15.4%.
Conclusion: EUS must be considered the first-intention method in localizing PETs and is helpful in decision making and management of GEP endocrine tumors.