Many drugs are known to affect the liver. The clinician must have a patient's complete drug history which should include prescription, nonprescription, and food items that may be toxic in order to make a determination of a drug reaction. The pathologist may not always have immediate access to the patient's drug history, so they must be aware of the characteristic histologic patterns of drug induced liver disease (hepatitis).
Several factors may contribute to drug induced liver disease in patients such as allergic reaction, lack of genetic enzymes necessary for drug metabolism, hypersensitivity, and autoimmune reaction. Each factor is attributed to unique histologic characteristics, including the location of liver damage. Liver damage may be seen in the hepatocytes or the biliary system and can be either diffuse or zonal. Unique histologic characteristics may include the presence of eosinophils, fatty changes, necrosis, vascular changes, and cellular inflammation.