Selected patients with hepatocellular carcinoma are candidates to receive potentially curative treatments, such as hepatic resection or liver transplantation, but nevertheless there is a high risk of tumor recurrence. Microvascular invasion is a histological feature of hepatocellular carcinoma related to aggressive biological behavior. We systematically reviewed 20 observational studies that addressed the prognostic impact of microvascular invasion, either after liver transplantation or resection. Outcomes were disease-free survival and overall survival. In liver transplantation, the presence of microvascular invasion shortened disease-free survival at 3 years (relative risk (RR)=3.41 [2.05-5.7]; five studies, n=651) and overall survival both at 3 years (RR=2.41 [1.72-3.37]; five studies, n=1,938) and 5 years (RR=2.29 [1.85-2.83]; six studies, n=2,003). After liver resection, microvascular invasion impacted disease-free survival at 3 and 5 years (RR=1.82 [1.61-2.07] and RR=1.51 [1.29-1.77]; four studies, n=1,501 for both comparisons). However inter/intraobserver variability in reporting and the lack of definition and grading of microvascular invasion has led to great heterogeneity in evaluating this histological feature in hepatocellular carcinoma. Thus, there is an urgent need to clarify this issue, because determining prognosis and response to therapy have become important in the current management of hepatocellular carcinoma. In this systematic review, we summarize the diagnostic and prognostic data concerning microvascular invasion in hepatocellular carcinoma and present a basis for consensus on its definition.

Liver transplant patients General population Severe COVID-19 Highlights The incidence of coronavirus disease 2019 (COVID-19) is higher in liver transplant patients. Mortality rates are lower than those observed in the matched general population. Immunosuppression withdrawal may not be justified. Mycophenolate may increase the risk of severe COVID-19 in a dosedependent manner.

After allotransplantation, cytomegalovirus (CMV) may be transmitted from the donor organ, giving rise to primary infection in a CMV negative recipient or reinfection in one who is CMV positive. In addition, latent CMV may reactivate in a CMV positive recipient. In this study, serial blood samples from 689 kidney or liver transplant recipients were tested for CMV DNA by quantitative PCR. CMV was managed using preemptive antiviral therapy and no patient received antiviral prophylaxis. Dynamic and quantitative measures of viremia and treatment were assessed. Median peak viral load, duration of viremia and duration of treatment were highest during primary infection, followed by reinfection then reactivation. In patients who experienced a second episode of viremia, the viral replication rate was significantly slower than in the first episode. Our data provide a clear demonstration of the immune control of CMV in immunosuppressed patients and emphasize the effectiveness of the preemptive approach for prevention of CMV syndrome and end organ disease. Overall, our findings provide quantitative biomarkers which can be used in pharmacodynamic assessments of the ability of novel CMV vaccines or antiviral drugs to reduce or even interrupt such transmission.