Intrahepatic Duct Dilatation Caused by Extrahepatic Billiary Obstruction' Morphologic Differentiation Between Benign and Malignant Disease on CT Scan

ABSTRACT

PURPOSE: Retrospective studies were carried out to evaluate the usufulness of CT in differentiating benign or malignant intrahepatic duct(IHD) dilatation due to extrahepatic duct(EHD) obstruction. MATERIALS AND METHODS: Among 75 cases of IHD dilatation, 35 cases(47%) which did not show causative lesion on CT were classified into central or peripheral type according to the extent of the dilatation and into pruned or beaded form according to its pattern. We considered central type or pruned form as a benign feature while peripheral type or beaded from as a malignant feature. Predictions of benignancy or malignancy were made according to the pattern and the extent of IHD dilatation. In all 75 cases, maximum caliber of IHD at portal vein bifurcation were examined. RESULTS: In regard to the classification of the extent, 80% (28 out of the 35 cases11 of 15 cases of benignancy and 17 of 20 cases of malignancy) of our prediction was correct. As to the classification of the pattern, similar results(82% correct prediction) were obtained(14 out of 17 cases)ln 15 cases of benignancy, we observed six cases of pruning and 1 case of beading. Among the 20 cases of malignancy, two cases of pruning and eight cases of beading of IHD dilatation were observed. Mean diameters of IHD at portal vein bifurcation were 10.1ram in benignancy and 15.1mm in malignancy.(Diameters less than 11mm was suggestive of benignancy(alpha =0.05). CONCLUSION: Evaluation of the extent, the pattern, and the degree of IHD dilatation is necessary in differential diagnosis of benignancy and malignancy of EHD obstruction. We conclude that CT is a useful tool for this purpose of differential diagnosis of the benignancy and the malignancy of extrahepatic biliary obstruction.