Letrozole-induced hepatitis with autoimmune features: a rare adverse drug reaction with review of the relevant literature

While aromatase inhibitors (AIs) have been known to cause minor elevations in liver enzymes, severe hepatotoxicity is rare. To the best of our knowledge, this is the first reported case of Letrozole-induced hepatitis with autoimmune features. A 70-year-old female with estrogen positive, invasive ductal carcinoma of the breast, presented with jaundice 3 months after starting letrozole. Hepatic transaminases were markedly elevated and her ANA and anti-smooth muscle antibody was positive. Liver biopsy featured drug-induced hepatitis. After stopping letrozole, liver tests trended back to normal within 3 weeks. She scored 9 for Roussel-Uclaf Causality Assessment Method (RUCAM). Over the last 10 years, there have been reported cases of drug-induced hepatitis secondary to AIs. We anticipate that there will be more widespread use of AIs based on recommendations from the TEXT, SOFT and extended AI trials. Therefore, physicians must be aware of this rare but life-threatening complication.