Evaluation of intraductal ultrasonography of the pancreas for intraductal papillary tumor

Intraductal ultrasonography of the pancreas was performed in 20 cases of Intraductal papillary tumor (IDT). Findings included multilocular cysts, increased wall thickness, mural nodules, mucus echos and mass with a mixed pattern of high and low echo. Mural nodules were observed only in cases of adenoma and adenocarcinoma. On the basis of the ultrasonographic findings and histopathological findings, the images of IDT were classified into four types : Type I lacked any nodule or wall thickening ; Type II had a nodule or wall thickness under 3 mm ; Type III had a nodule or wall thickness over 4 mm, or a cyst including tumor ; Type IV had a mass with a mixed pattern, or interruption of the pancreatic duct wall. Type I or II tumors were confirmed to be hyperplasia or adenoma. Taking types III and IV as index of malignant findings, sensitivity was 100%, specificity was 82% and the accuracy rate was 89%. IDUS was usefull for differential diagnosis of benign and malignant IDT.