Immunotherapy-Induced Hepatitis Mimicking Sclerosing Cholangitis in a Patient With Metastatic Triple-Negative Breast Cancer.

Immune checkpoint inhibitors (ICIs) have emerged as a promising treatment for metastatic triple-negative breast cancer (TNBC), particularly in programmed death-ligand 1 (PD-L1)-positive tumors. However, their use is associated with immune-related adverse events (irAEs), including hepatotoxicity, which, although rare, can be severe and challenging to diagnose. We present the case of a 59-year-old woman with metastatic TNBC who developed immune-related liver toxicity following 14 cycles of atezolizumab in combination with nab-paclitaxel. The patient presented with jaundice, pruritus, and transaminitis. Liver biopsy revealed nonspecific findings, including interface hepatitis and early fibrosis, without features definitive for sclerosing cholangitis. A comprehensive workup excluded viral, autoimmune, and other drug-induced causes. Based on clinical timing, exclusion of alternative etiologies, and histopathologic correlation, a diagnosis of ICI-induced hepatitis was made. The patient responded well to corticosteroid therapy with budesonide, showing gradual improvement in liver enzyme levels. This case underscores the importance of maintaining a high index of suspicion for immune-related hepatotoxicity in patients receiving ICIs, especially those with underlying liver conditions, and highlights the need for timely diagnosis and individualized immunosuppressive treatment.