Atypical autoimmune hepatitis presenting as acute hepatitis with prominent cholestatic features: a case report.

Autoimmune hepatitis (AIH) poses distinct diagnostic challenges due to its heterogeneous clinical presentation and lack of disease-specific features. This is further complicated by drug-induced liver injury (DILI), which can present with laboratory and histological findings indistinguishable from those of AIH. Here, we report the case of an elderly man who presented with elevated liver enzymes of unclear etiology. Initial laboratory tests showed negative antinuclear antibody (ANA) and normal serum immunoglobulin G (IgG) levels. Based on his history of consuming herbal supplements and a liver biopsy showing acute cholestatic hepatitis with cholangitis lenta, a diagnosis of DILI was initially considered. During a 1-year follow-up, two recurrent episodes of elevated liver enzymes and urine discoloration were observed. Concurrent laboratory tests revealed seroconversion to ANA positivity and an IgG level exceeding 1.2 times the upper limit of normal (ULN). A follow-up liver biopsy demonstrated typical histopathological features of AIH. In summary, repeated evaluations-including two liver biopsies and a year-long clinical follow-up-confirmed the diagnosis of AIH. This case underscores the importance of considering AIH in patients who initially present with acute hepatitis with prominent cholestatic features, even when the early clinical picture is atypical.