# Morphological and Immunohistochemical Characteristics of Liver Inflammation in Patients with a History of COVID-19

## TL;DR

This study examines liver inflammation in patients who had COVID-19, finding increased immune cell activity and tissue regeneration compared to controls.

## Contribution

The study provides new insights into liver pathology in post-COVID-19 patients, highlighting immune cell changes and regenerative processes.

## Key findings

- Post-COVID-19 patients showed higher CD3+ lymphocyte counts and lower CD68+ macrophage counts compared to controls.
- Regenerative changes in hepatocytes and biliary epithelium were more frequent and extensive in post-COVID-19 patients.
- No significant fibrosis or vascular changes were observed in post-COVID-19 patients.

## Abstract

The COVID-19 pandemic caused more than seven million deaths, mostly via acute respiratory distress syndrome with microvascular thrombosis. Compared to the amount of information about pulmonary pathology, information about COVID-19-induced liver lesions is scarce, especially with regard to the long-term consequences. The aim of our study was to evaluate inflammatory, vascular and fibrotic changes in hepatobiliary tissues of patients with a history of COVID-19 (post-COVID-19 patients). Based on the Knodell score, moderate portal inflammation was observed in 41.2% of post-COVID-19 patients, contrasting with 14.3% of control cases (p = 0.06). Moderate periportal inflammation was present in 26.5% and 7.1% of patients, respectively (p = 0.08). Post-COVID-19 patients showed higher counts of CD3+ lymphocytes (p = 0.02) and lower counts of CD68+ macrophages (p = 0.04), as well as more frequent and extensive regenerative changes in hepatocytes and the biliary epithelium (p = 0.0007). We did not find significant fibrosis or pathological changes in blood vessels, and only mild steatosis was observed in both groups.