AIM: To evaluate the relationship between hepatocellular carcinoma(HCC) vascularity and grade; to describe patterns and vascular/histopathological variations of post-transplantation recurrence.METHODS: This retrospective study included 165 patients(143 men, 22 women; median age 56.8 years, range 28-70.4 years) transplanted for HCC who had a follow-up period longer than 2 mo. Pre-transplantation dynamic computed tomography or magnetic resonance examinations were retrospectively reviewed, classifying HCC imaging enhancement pattern into hypervascular and hypovascular based on presence of wash-in during arterial phase. All pathologic reports of the explanted livers were reviewed, collecting data about HCC differentiation degree. The association between imaging vascular pattern and pathological grade was estimated using the Fisher exact test. All follow-up clinical and imaging data were reviewed for evidence of recurrence. Recurrence rate was calculated and imaging features of recurrent tumor were collected, classifying early and late recurrences based on timing(< or ≥ 2 years after transplantation) and intrahepatic, extrahepatic and both intrahepatic and extrahepatic recurrences based onlocation. All intrahepatic recurrences were classified as hypervascular or hypovascular and the differentiation degree was collected where available. The presence of variations in imaging enhancement pattern and pathological grade between the primary tumor and the intrahepatic recurrence was evaluated and the association between imaging and histopatholgical variations was estimated by using the χ2 test. RESULTS: Of the 163 patients with imaging evidence of viable tumor, 156(95.7%) had hypervascular and 7(4.3%) hypovascular HCC. Among the 125 patients with evidence of viable tumor in the explanted liver, 19(15.2%) had grade 1, 56(44.8%) grade 2, 40(32%) grade 3 and 4(3.2%) grade 4 HCC, while the differentiation degree was not assessable for 6 patients(4.8%). A significant association was found between imaging vascularity and pathological grade(P = 0.035). Post-transplantation recurrence rate was 14.55%(24/165). All recurrences occurred in patients who had a hypervascular primary tumor. Three patients(12.5%) experienced late recurrence; the location of the first recurrence was extrahepatic in 14 patients(58.3%), intrahepatic in 7 patients(29.2%) and both intrahepatic and extrahepatic in 3 patients(12.5%). Two patients had a variation in imaging characteristics between the primary HCC(hypervascular) and the intrahepatic recurrent HCC(hypovascular), while 1 patient had a variation of histopathological characteristics(from moderate to poor differentiation), however no association was found between imaging and histopathological variations.CONCLUSION: A correlation was found between HCC grade and vascularity; some degree of variability may exist between the primary and the recurrence imaging/histopathological characteristics, apparently not correlated. To evaluate the relationship between hepatocellular carcinoma (HCC) vascularity and grade; to describe patterns and vascular / histopathological variations of post-transplantation recurrence. METHODS: This retrospective study included 165 patients (143 men, 22 women; median age 56.8 years, range 28-70.4 years) transplanted for HCC who had a follow-up period longer than 2 mo. Pre-transplantation dynamic computed tomography or magnetic resonance examinations were retrospectively reviewed, classifying HCC imaging enhancement pattern into hypervascular and hypovascular based on presence of wash- All pathologic reports of the explanted livers were reviewed, collecting data about HCC differentiation degree. The association between imaging vascular pattern and pathological grade was estimated using the Fisher exact test. All follow-up clinical and imaging data were reviewed for evidence of recurrence. Recurrence rate was calculated and imaging features of recurrent tu mor were collected, classifying early and late recurrences based on timing (