title: Endosonography of insulin-secreting and clinically non-functioning neuroendocrine tumors of the pancreas: criteria for benignancy and malignancy.
abstract: OBJECTIVE
  Endosonography is a powerful tool in the diagnosis of gastroenteropancreatic neuroendocrine tumors. This study was performed in order to characterize endosonographic criteria of malignant and benign neuroendocrine pancreatic tumors focussing on those typically presented to endocrinologists, i.e. insulin-secreting tumors and clinically non-functioning tumors in MEN-1.
  
  
  METHODS
  We studied six benign insulinomas, four hormone inactive benign neuroendocrine adenomas in MEN-1, and three non-metastatic neuroendocrine carcinomas with clinically symptomatic insulin secretion.
  
  
  METHODS
  Endosonography was performed using Pentax FG 32 UA endosonoscope with a longitudinal 7.5 MHz sector array.
  
  
  RESULTS
  Tumor diameter was larger in malignant tumors (19 - 70 / 47.0 +/- 25.9 mm) than in benign lesions (2.3 - 19 / 9.7 +/- 5.8 mm). Hypoechoic echogeneity was more or less present in benign and in malignant tumors and could not be used as a criteria for differential diagnosis. Heterogeneous or multinodular structure on endosonographic imaging however, was an exclusive feature of malignant tumors. Echo-free areas representing cystic transformation or necrosis and vascular invasion were additional signs of malignancy.
  
  
  CONCLUSIONS
  Molecular genetic diagnosis of MEN-1 and new therapeutic developments such as endoscopic surgery make sufficient imaging procedures in the management of neuroendocrine pancreatic tumors mandatory. Besides valid detection and exact localization, endosonography provides criteria for benign and malignant tumors and thus may be helpful in planning therapeutic strategies.
authors.affiliation: Department of Internal Medicine, Endocrinology and Metabolic Diseases, Johannes Gutenberg University Hospital, D-55101 Mainz, Germany. pkann@mail.uni-mainz.de
authors.forename: P
authors.initials: P
authors.lastname: Kann
authors.forename: F
authors.initials: F
authors.lastname: Bittinger
authors.forename: M
authors.initials: M
authors.lastname: Engelbach
authors.forename: S
authors.initials: S
authors.lastname: Bohner
authors.forename: A
authors.initials: A
authors.lastname: Weis
authors.forename: J
authors.initials: J
authors.lastname: Beyer
mesh_terms: D018278:Carcinoma, Neuroendocrine / Q000000981:diagnostic imaging* / Q000378:metabolism; D003937:Diagnosis, Differential; D019160:Endosonography; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000000981:diagnostic imaging* / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism
chemical_list: D007328:Insulin