Pediatric Acute Liver Failure: A Clinicopathological Perspective

Could Herpesviridae be the cause of severe acute hepatitis of unknown origin in children?

INTRODUCTION

Severe acute hepatitis (SAH) is defined by a severe inflammation of hepatocytes in the liver parenchyma which can lead to an acute liver failure, a clinical condition with high mortality rate that can be triggered by several factors but is usually associated to hepatotropic viruses' infection. In 2022, cases of children with severe acute hepatitis of unknown origin hospitalized in Glasgow, Scotland, were reported. Possible causes of this condition include, but are not limited to, undiagnosed viral (and non-viral) infections, autoimmune hepatitis, drug and/or chemical toxicity, mitochondrial chain respiratory and metabolic disorders.

AREAS COVERED

Herpesviruses can cause severe acute hepatitis, but little is known about the role and the mechanisms of herpesviruses as a causative agent of this type of hepatitis. We review the role of herpesviruses as causative agent of SAH in children and other possible mechanisms involved in this disease.

EXPERT OPINION

Differential diagnosis for herpesvirus in SAH should be implemented in all settings. Alternative fluids, such as saliva and dried blood, could be used in the diagnosis to overwhelm the availability of biological specimens at sufficient volume. In the future, genetic studies could also be added to increase the knowledge about severe acute hepatitis in children.

Clinicopathologic Features of Severe Acute Hepatitis Associated With Adenovirus Infection in Children

A recent increase in reports of severe acute hepatitis of unknown etiology in children is under investigation. Although adenovirus has been frequently detected, its role remains unclear, and systematic histopathologic analysis is lacking. We conducted a retrospective study of 11 children hospitalized between October 2021 and May 2022 with unexplained acute hepatitis and concurrent adenovirus infection. Liver biopsies collected shortly after admission demonstrated moderately to severely active hepatitis in 8/11 (73%) cases, characterized by marked portal mixed inflammation, moderate-to-severe interface activity, and milder lobular inflammation. Clusters of plasma cells were present in 6/11 (55%) cases, mimicking autoimmune hepatitis. Semiquantitative scoring of 17 discrete histologic features found that greater degrees of portal inflammation, interface activity, bile duct injury, bile ductular reaction, lobular inflammation, Kupffer cell activation, and hepatocyte focal necrosis were significantly more common in these cases in comparison to the control group of unexplained acute severe hepatitis without adenovirus infection. Liver biopsy immunohistochemistry was negative for adenovirus in all cases. Polymerase chain reaction testing of liver tissue was positive for the enteric adenovirus serotypes 41 (species F) in 10/11 (91%) cases. An immunoprofile study of hepatic infiltrating lymphocytes in 1 patient revealed the presence of large numbers of CD3 + and CD4 + lymphocytes. Nine patients received supportive treatment without steroids and recovered without the need for liver transplantation. In summary, liver injury in children with severe acute hepatitis and adenovirus infection is characterized by a hepatitic pattern that resembles severe autoimmune hepatitis and may represent an immune-mediated process associated with viral infection.

Suspected Adenovirus Causing an Emerging HEPATITIS among Children below 10 Years: A Review

In October 2021, a case of acute hepatic failure without any known cause was identified in the United States of America. Upon further investigation, other children aged 1–6 years were reported to have the same liver failure, and some of them were positive for adenovirus 41 type F. On 21 April 2022, the Centers for Disease Control and Prevention (CDC) released an alert after 74 cases were identified in United Kingdom (UK) between 5 and 8 April in children below 10 years of age, some of whom were also found to be positive for SARS-CoV-2. All the patients showed symptoms such as vomiting, diarrhea, jaundice, and abdominal pain. The patients’ liver enzymes were remarkably increased. A total of 650 cases had been reported from 33 countries as of 27 May 2022, among which 222 cases were reported in the UK alone. No connection with SARS-CoV-2 or its vaccine has been found so far. However, the suspected cause is adenovirus, including its genomic variations, because its pathogenesis and laboratory investigations have been positively linked. Until further evidence emerges, hygiene precautions could be helpful to prevent its spread.