Clinicopathological characteristics of autoimmune‑like hepatitis after drug‑induced liver injury.

Autoimmune hepatitis (AIH) can be induced by drugs, but the underlying mechanisms remain unclear. The present study attempted to elucidate the clinicopathological characteristics of autoimmune-like hepatitis following drug-induced liver injury (DILI-ALH). The medical records of 57 patients diagnosed with AIH at Mie General Medical Center (Yokkaichi, Japan) were retrospectively reviewed, paying particular attention to the history of drug administration. Patients were classified into three groups: De novo AIH, drug-induced ALH (DI-ALH) and DILI-ALH. DILI-ALH was newly defined as cases in which the patient had a history of DILI and where the liver injury initially improved after drug discontinuation, but later worsened and was diagnosed as AIH. Of the 57 patients diagnosed with AIH, 42 patients were included in this study. De novo AIH was diagnosed in 29 patients, DI-ALH in 10 patients and DILI-ALH in 3 patients. Suspected causative drugs for drug-related pathologies were variable, including statins, health foods and supplements. No significant differences in sex or mean age were observed for DI-ALH and DILI-ALH compared with those for AIH. Distinguishing DI-ALH or DILI-ALH from AIH serologically and pathologically is difficult. No significant differences in the number of steroids used or the recurrence rate were observed between any groups. These findings suggest that drugs may present a more diverse cause of ALH than generally predicted. In particular, some AIH cases clearly present with DILI-ALH. Clarifying the involvement of drugs in the pathogenesis of AIH and establishing guidelines for diagnosis and treatment represent important issues for the future.