accurately distinguish them before the determination of therapy (i.e., liver transplantation). Our data show that the application of the American Association for the Study of Liver Diseases guidelines prevents a false-positive diagnosis of ICC in cirrhosis. Small ICC may display an early enhancement (partial or total) in the arterial phase. This is similar to the HCC pattern, but because we have not observed washout in delayed phases, this finding is confirmed to be specific for HCC 2,3 and critical for nodule diagnosis.
We focused our analysis on ICC arising within a cirrhotic liver; this constituted most of the cases detected in the setting of a surveillance program for early HCC diagnosis. The majority of the published series evaluating the computed tomography and magnetic resonance imaging features of ICC did not restrict the analysis to only patients with cirrhosis, and most of the cases were detected in the presence of symptoms, so the lesions usually were larger. We already acknowledged in the discussion that the number of patients recruited was limited, but even so, this is the largest cohort of ICC in cirrhosis. More importantly, more than two-thirds of the nodules were smaller than 3 cm, and the challenge of imaging characterization lies in small nodules.
Regarding the previously reported delayed washout in ICC, 4 we have to stress again that the reported "washout" of ICC cannot be confused with the typical washout of HCC in delayed phases. The former still enhances more than the hepatic parenchyma, whereas the latter typically has lower enhancement in delayed phases with respect to the liver.
In conclusion, our data show that small ICC may mimic the pattern of HCC in the arterial phases of magnetic resonance imaging, but this tumor does not show washout in the delayed venous phase. This is specific for HCC and may allow a noninvasive HCC diagnosis, but if it is not observed, diagnostic biopsy should be mandatory, as already recommended in the American Association for the Study of Liver Diseases guidelines.