The pathology of drug-induced liver injury

The liver biopsy is frequently used as an adjunct diagnostic test in the evaluation of drug-induced liver injury (DILI). A biopsy may be performed to confirm the diagnosis, especially when there is a complex clinical differential diagnosis that includes DILI. A biopsy can also be used to stage the severity of hepatotoxicity so that a necessary agent may be continued. Alternatively, a drug or toxin may only be implicated after a biopsy is performed, particularly in the case of subacute or chronic liver injury. The pathologist should approach the biopsy systematically by first classifying the disease and then working with the clinician to include or exclude etiologies in the pathological differential diagnosis. This article outlines a practical approach to the diagnosis of DILI on liver biopsy, including the common patterns of injury observed in drug- and toxin-induced liver pathology and prognostic pathological features that may be associated with the outcome of patients with DILI.