The amount of liver tissue is essential for accurate histological staging in patients with autoimmune hepatitis.

Abstract

The gold standard for the evaluation of liver fibrosis is histology. However, the heterogenous distribution of fibrosis limits the sensitivity of histology. The collection of two samples with a 16G needle is therefore recommended to reduce the risk of sampling error. The aim of this study was to investigate whether this standard is also applicable to patients with autoimmune hepatitis (AIH). This retrospective study included patients with AIH, who underwent mini-laparoscopic biopsy at our center between 2011 and 2020 (n = 32). Diagnosis was verified by usage of the simplified AIH score (≥ 6). Patients were categorized into three groups, based on the number of portal fields (PF) in the collected liver tissue (< 10 PF, 10 - 19 PF, ≥ 20 PF). We correlated the histological staging for these groups with the mini-laparoscopic fibrosis score (MLFS). Furthermore, non-invasive methods for the assessment of fibrosis were correlated with the histological staging (acoustic radiation force impulse (ARFI) and FIB-4 score). MLFS correlated well with histological staging (r = 0.649, p = 0.0001). The correlation between MLFS and histology improved with higher numbers of histologically analyzed portal fields (< 10 PF: r = 0.400, p = 0.378; 10 - 19 PF: r = 0.5467, p = 0.023; ≥ 20 PF: r = 0.956, p = 0.0002). The probability of collecting at least 10 or 20 portal fields was dependent on the number and diameter of the samples. For all patients with at least two 16G biopsies, 10 or more PF were available. With three 16G biopsies, at least 20 PF were obtained for all patients. ARFI correlated with MLFS and histological staging only in patients with low/moderate-grade inflammation as defined by ALT < 10xULN (upper limit of normal) (MLFS: r = 0.723; p = 0.004; histology: r = 0.619, p = 0.018). FIB-4 did not correlate with histological staging. The amount of liver tissue obtained by liver biopsy is crucial to minimalize the risk of sampling error and thus underestimation of fibrosis. This study was the first to investigate the amount of liver tissue required for histological staging in AIH. Our data suggest that diagnostic accuracy is likely to be higher with 20 PF compared to the generally recommended 10 PF. We therefore recommend to perform three biopsies with a 16G needle in (suspected) AIH patients. ARFI correlated well with histological staging unless inflammatory activity is high.