The eosinophilias, including the idiopathic hypereosinophilic syndrome.

INTRODUCTION

Recently, medical interest has been growing in SARS-CoV-2 infection and its multiorgan involvement, including the liver. Up until now, a few reports have described autoimmune hepatitis (AIH) triggered by SARS-CoV-2 infection, but no data are available about the specific liver inflammatory infiltrate and cluster of differentiation. We report a case of AIH triggered by SARS-CoV-2 infection, with a particular focus on its histological and mainly immunohistochemical features.

CASE DESCRIPTION: A 60-year-old man, with a history of paucisymptomatic SARS-CoV-2 infection that occurred one month earlier, was admitted for alterations of hepatocellular necrosis and cholestasis indexes. He completed vaccination for SARS-CoV-2 a year earlier. The serologies for hepatotropic viruses were negative. The anti- smooth muscle antibodies (ASMA) and antinuclear antibodies (ANA) results were positive. Anti-liver kidney microsome (anti-LKM) antibodies and antimitochondrial (AMA) were negative. By liver biopsy, haematoxylin-eosin staining highlighted severe portal inflammation with a rich CD38+ plasma cell component, while immunohistochemical staining showed low cell CD4+ count and prevalence of CD8+ and CD3+. After biopsy, the patient started an immunosuppressant regimen, with benefit.

DISCUSSION: We can conclude that the patient developed a type 1 AIH triggered by SARS-CoV-2 infection. The presence of CD8 T-cells at immunohistochemical examination suggests different mechanisms from classic AIH. Similar cases are described after AIH triggered by SARS-CoV-2 vaccination.

CONCLUSION

The AIH after SARS-CoV-2 infection developed by the patient showed a histological picture similar to a classic AIH for the abundant presence of plasma cells, and immunohistochemical features similar to those described after SARS-CoV-2-vaccination.

LEARNING POINTS: Recently, medical interest has been growing in SARS-CoV-2 infection and its multiorgan involvement, including the liver. Underlying mechanisms are not still clear, more likely consisting of an inflammatory and immune mediated process rather than a direct cytopathic damage.Our report describes a rare case of type 1 AIH triggered by SARS-CoV-2 infection, showing a peculiar histological pattern, different from classic AIH, conversely similar to AIH triggered by SARS-CoV-2 vaccination.The mechanisms underlying liver involvement in SARS-CoV-2 infection are still under investigation. Further studies should be encouraged to improve understanding on this focus and to support physicians in its management.