Severe azathioprine-induced liver injury 22 months after initiation of treatment

Drug-induced liver injury (DILI) is the leading cause of acute liver failure in high-income countries. Acute cholestasis is one of the most common forms of hepatotoxicity induced by azathioprine. It usually begins during the first year of treatment, with most cases reported during the first month. We describe an uncommon case of DILI that occurred after 22 months of drug administration. A woman in her 50s was hospitalised because of jaundice and asthenia. She had been treated with azathioprine for myasthenia gravis during the last 2 years. Acute cholestatic injury was diagnosed. After ruling out most common causes of cholestasis, azathioprine was withdrawn and subsequent histological findings in liver biopsy were consistent with drug-induced cholestatic liver damage. After discontinuation of azathioprine, biochemical parameters progressively normalised and remarkable clinical improvement was achieved. With this report, we suggest that azathioprine should be considered among the causes of liver injury, despite long treatment duration.