Diagnosis of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis: Why liver biopsy is essential.

The pattern of non-alcoholic fatty liver disease is complex with an association of several lesions, each of them related to different pathophysiological mechanisms. Despite the progress in non-invasive tools, liver biopsy remains the only diagnostic procedure that can reliably assess these various patterns, their related severity and associations. The most important difficulties of liver biopsy can be avoided if this procedure is performed by an experienced hepatologist and read by a liver pathologist. However, for obvious reasons, biopsy should be restricted to selected patients, especially in the context of clinical trials. Indeed, liver biopsy is considered mandatory by regulatory authorities as a surrogate to assess drug efficacy in Phase 3 clinical trials. In addition to the clinical diagnosis, liver biopsy can be used to score the various histological patterns of disease (NASH-CRN, SAF scores) and accurately assess the extent of fibrosis, both of which are useful when follow-up biopsies are performed. When treatment becomes available in the near future, liver biopsy could remain useful for choosing the most suitable therapeutic option based on the main predominant histological features (activity, steatosis, fibrosis).