title: Differential diagnosis of benign versus malignant nonfunctioning islet cell tumors of the pancreas: the roles of EUS and ERCP.
abstract: BACKGROUND
  Differentiation between benign and malignant nonfunctioning islet cell tumors of the pancreas before surgery is often difficult. The roles of EUS and ERCP were evaluated in the differential diagnosis of these tumors.
  
  
  METHODS
  Seven patients with histologically confirmed nonfunctioning islet cell tumors (4 benign, 3 malignant) underwent EUS and ERCP.
  
  
  METHODS
  EUS demonstrated a homogeneous hypoechoic mass or a hypoechoic mass with a regular central echogenic area in the 4 cases of benign tumor, and a hypoechoic mass with an irregular central echogenic area in all 3 cases of malignant tumor. The irregular central echogenic area corresponded to severe hemorrhage, necrosis, or fibrosis with hyalinosis (hyaline degeneration) on pathologic examination. ERCP demonstrated displacement or complete obstruction (because of ductal invasion) of the main pancreatic duct in 2 patients with malignant tumors and no abnormalities in the other 5 cases.
  
  
  CONCLUSIONS
  In patients with nonfunctioning islet cell tumors, a hypoechoic mass with an irregular central echogenic area on EUS or complete obstruction of the main pancreatic duct on ERCP suggests malignancy.
authors.affiliation: First Department of Surgery, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Nobutsugu
authors.initials: N
authors.lastname: Abe
authors.forename: Yumi
authors.initials: Y
authors.lastname: Izumisato
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Taro
authors.initials: T
authors.lastname: Yamato
authors.forename: Makoto
authors.initials: M
authors.lastname: Tokuhara
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Masaki
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Mori
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Atomi
mesh_terms: D007516:Adenoma, Islet Cell / Q000175:diagnosis* / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D018273:Carcinoma, Islet Cell / Q000175:diagnosis* / Q000000981:diagnostic imaging; D002760:Cholangiopancreatography, Endoscopic Retrograde; D003937:Diagnosis, Differential; D019160:Endosonography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging