Antimitochondrial Antibody-Negative Primary Biliary Cholangitis: A Retrospective Diagnosis

Primary biliary cholangitis (PBC) is an inflammatory cholestatic disease that tends to worsen, leading to hepatic cirrhosis and portal hypertension. We present a case of a middle-aged female who presented with progressively worsening generalized itch; the examination was significant only for urticarial rash and facial swelling. Investigation revealed direct hyperbilirubinemia, mildly elevated transaminase, and significant elevation of alkaline phosphatase. A differential was performed with labs including antimitochondrial antibodies (AMA) for PBC, hepatitis panel, anti-smooth muscle antibodies for autoimmune hepatitis, and tissue transglutaminase IgA for celiac disease, all of which were unremarkable. The patient was empirically treated with ursodeoxycholic acid (UDCA). Given the excellent clinical response at the three-week follow-up to treatment despite negative AMA, further testing with anti-sp100 and anti-gp210 was pursued, which returned positive for anti-sp100, confirming the diagnosis of PBC.