The histopathological evaluation of drug-induced liver injury.

Drug-induced liver injury (DILI) presents unique challenges to the pathologist. It is not only an uncommon reason for liver biopsy, but the pathology of DILI is spread across the entire spectrum of hepatic injury patterns. It is important for the pathologist to suspect DILI when the histological changes are unusual or out of synchronicity with the patient's history. A systematic evaluation approach will yield the most information. It begins with the characterization of the general pattern of injury which, for most cases, will be found in a handful of necroinflammatory and cholestatic patterns. A careful assessment of the severity of injury across the various anatomic compartments will provide information on the probable natural history of the injury. Correlation of liver injury with the patient's medication history and clinical findings will help to narrow the differential diagnosis, particularly when it is recognized that most drugs have a limited range of histological findings and vary in their propensity to cause injury. This review provides an overview of the assessment of the liver biopsy and its use to confirm or exclude particular drugs as contributing to the patient's liver injury.