RE: Diffusion-weighted MRI in intrahepatic bile duct adenoma arising from the cirrhotic liver.

We have read with great interest the recent case report of An et al. (1) revealing an intrahepatic bile duct adenoma (BDA) arising from a cirrhotic liver that was studied using both diffusion-weighted imaging (DWI) and gadolinium-ethoxybenzyl-diethylene triamine pentaacetic acid-enhanced magnetic resonance imaging. They stated that the BDA showed an apparent diffusion coefficient (ADC) two-fold greater than that of the background liver parenchyma on DWI. In our opinion, some points about the report are not sufficiently clear.

They declared that the ADC values of the BDA may have been higher than the background liver parenchyma due to its histological features. Nevertheless, they report a patient with alcoholic liver cirrhosis, and ADC values of patients with cirrhosis are lower than those of patients with a healthy liver (2) and nonfibrotic liver lesion ADCs (3). This feature may have affected the difference in ADC values, which might not have been seen between the ADC values of the BDA and the background liver parenchyma.

Bile duct adenoma is histologically recognized as a benign lesion composed of noncystic ductules, and variable degrees of inflammation and fibrosis. This histological spectrum of the lesion could also alter the ADC values of different BDA lesions (4).

We hope that these comments will add to the value of the article by An et al. (1).