Diagnosis of mucin-producing tumor of the pancreas with an intraductal ultrasonographic system.

The purpose of this study is to examine the usefulness of intraductal ultrasonography at a frequency of 20 or 30 MHz in the diagnosis of mucin-producing tumor. The subjects were 66 patients with mucin-producing tumor (10 with main pancreatic duct type tumor and 56 with branch type tumor) who had also undergone endoscopic ultrasonography. In main pancreatic duct type tumors, we could diagnose the extent of the tumor and evaluate the invasion of the tumor into the pancreatic parenchyma in all seven patients who had undergone resection (three invasive tumors, four noninvasive tumors). Sixteen of 32 resected branch type tumors showing mural nodules with intraductal sonography were carcinoma or adenoma. On comparing intraductal and endoscopic ultrasonography in the rate of detecting nodules, in five tumors (one carcinoma and four adenomas), nodules were detected only with intraductal ultrasonography. In conclusion, intraductal ultrasonography is very useful for the diagnosis in the main pancreatic duct type tumor and in the detection of mural nodules in the branch type tumor.