Clinicopathological Study of Autoimmune Hepatitis Cases That Were Difficult to Differentiate from Drug-Induced Liver Injury

Aim: Acute-onset autoimmune hepatitis (AIH) histopathologically presents with features of acute hepatitis and lacks a specific diagnostic method. Also, AIH is often difficult to differentiate from drug-induced liver injury (DILI). We aimed to investigate the final clinical diagnosis of these cases, and compare the clinical, biochemical, and histological characteristics of AIH vs. DILI. Methods: We examined the Digestive Disease Week Japan 2004 (DDW-J) scale scores, AIH scores, clinical data, and pathological findings in 20 patients in whom it was difficult to differentiate autoimmune liver disease from DILI. Results: In cases with a DDW-J scale score of ≥5, there was a good correlation between the final diagnosis and DDW-J scale assessments, but in cases with a DDW-J scale score of ≦4 they did not correlate well. The scores for pathological findings, such as cobblestone hepatocellular change (p = 0.015), interface hepatitis (p = 0.012), and prominent plasma cells in portal areas (p = 0.011), were higher in the AIH group than in the DILI group. Conclusion: This study showed that DDW-J scale was useful for differentiating AIH from DILI in cases with a DDW-J scale score of ≧5. The histologic features of AIH were characterized by cobblestone hepatocellular change, interface hepatitis, and plasma cell infiltration of the portal region.