Diagnosis of mucin-producing tumor of the pancreas by balloon-catheter endoscopic retrograde pancreatography--compression study.

The procedure of choice for the treatment of mucin-producing pancreatic tumor (MPPT) remains controversial, since it includes not only malignant but also benign lesions. The purpose of the present study was to characterize 53 consecutive cases of MPPT and to elucidate the characteristics of benign or malignant MPPT according to the findings of an improved method of endoscopic retrograde pancreatography (ERP), namely balloon-catheter ERP-compression study (balloon ERP-CS), as well as endoscopic ultrasonography (EUS), in comparison with a histological examination. There were 37 male and 16 female cases with a median age of 63+/-11 (mean+/-SD). The balloon ERP-CS was performed in all cases, and the obtained pancreatograms were classified into two types: Main Duct type and Branch Duct type. The latter was further divided into subtypes A and B. The Branch Duct A type showed only cystic dilatation of the branch duct. If the main pancreatic duct downstream to a cyst showed more than a 5 mm dilatation, this was classified as a Branch Duct B type. Seventeen out of 19 Main duct types (89%) were histologically diagnosed as neoplasms including 13 lesions of cancer and 4 of adenoma. All the Branch Duct A type cases were diagnosed as hyperplasias. 23 Branch Duct B type cases contained 7 cancers, 8 adenomas, and 8 hyperplasias. In the Main Duct type, benign or malignant, the diagnostic ability of balloon ERP-CS was calculated as sensitivity 100%, specificity 40%, and accuracy 84%; in the Branch Duct type, sensitivity 73%, specificity 86%, and accuracy 82%. On EUS, it was found that the size of the tumor in the cyst, with respect to the maximum diameter as well as height, correlated well with the grade of malignancy. All tumors (n=35) greater than 20 mm in diameter were found to be cancerous. These findings indicate that the MPPT is highly suggestive of neoplasms when the dilatation of the main pancreatic duct is detected by balloon ERP-CS and when, in a case without dilatation of the main pancreatic duct, a nodular lesion greater than 10 mm in diameter is identified in the cyst by balloon ERP-CS as well as EUS. Our current patient management strategy for operations is as follows: Main Duct type patients and Branch Duct type patients with a nodular defect detected by balloon ERP-CS and with an elevation of more than 10 mm in EUS should have an operation. Other Branch Duct type patients without main pancreatic duct dilatation are followed up by balloon ERP-CS.