Antimitochondrial Antibody-Negative Primary Biliary Cholangitis in a Patient with a History of Colon Cancer and Chemotherapy: A Case Report.

Background: Primary biliary cholangitis (PBC) is a chronic, immune-mediated liver disease with progressive destruction of bile ducts, cirrhosis, and liver failure. Diagnosis is usually based on detecting antimitochondrial antibodies (AMA), found in 95% of patients with PBC. However, some patients test negative for AMA and other antibodies, which complicates the diagnosis process. Case Presentation: We report a case of a 57-year-old Syrian woman who presented with fatigue, jaundice, pruritus, and abdominal pain, and her medical history included colon cancer and chemotherapy. Laboratory tests showed liver fibrosis but were negative for AMA, antinuclear antibodies, and anti-smooth muscle antibodies, further complicating the diagnosis. A liver biopsy was performed and showed mixed fibrosis, cholangitis, and cholestasis, which led to the diagnosis of AMA-negative PBC. Conclusions: This case confirms the importance of liver biopsy in unclear cases of primary cholangitis. This case also highlights the patient's history of colon cancer and chemotherapy as a notable clinical observation, generating a hypothesis for a potential association that warrants further systematic investigation. A better understanding of such variants in PBC can enable early diagnosis and improve management strategies for affected patients.