P41 PBC-AIH overlap syndrome: clinical features and outcomes from a Moroccan cohort

<h3>Introduction</h3> The overlap syndrome between primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) is a rare and often underrecognized form of autoimmune liver disease. It presents clinical, immunological, and histological features of both conditions. Timely diagnosis is essential due to its prognostic and therapeutic implications. This study aimed to describe the clinical, biological, immunological, histological characteristics and therapeutic outcomes of patients with PBC-AIH overlap syndrome in a Moroccan cohort. <h3>Methods</h3> A retrospective descriptive study was conducted on 19 patients diagnosed with PBC-AIH overlap syndrome among 106 patients followed for PBC between 2012 and 2025. Diagnosis was based on the Paris criteria, which require at least two diagnostic features of both PBC and AIH (clinical, biological, immunological, or histological). All patients were treated with a combination of ursodeoxycholic acid (UDCA) and immunosuppressive therapy (corticosteroids with or without azathioprine). Treatment response was assessed after 6 months using the Paris II criteria for PBC and standard response criteria for AIH (normalization of transaminases, IgG levels, and histological improvement). <h3>Results</h3> The mean age was 51.5 years, with a strong female predominance (84%; 16 women, 3 men). Common presenting symptoms included jaundice (58%), fatigue (47.3%), and pruritus (37%). Associated autoimmune diseases were noted in 31.6% of patients, including autoimmune thyroiditis (10.5%), pernicious anemia (10.5%), Sjögren’s syndrome (5.3%), and systemic sclerosis (5.3%). Biological tests revealed elevated alkaline phosphatase in 78.9% and GGT in 89.5%. Significant hepatocellular injury (elevated transaminases) was observed in 26.3%. Immunologically, anti-mitochondrial M2 antibodies were positive in 47%, with SP100 and Gp210 positivity in 2 and 1 cases, respectively. Liver biopsy revealed interface hepatitis in 79% of cases. Fibrosis staging showed advanced disease: F3 in 58%, F2 in 21%, F4 in 11% and only 11% had F1 fibrosis. Hepatic decompensation occurred in 42.1%: neurologic (10.5%), ascitic (10.5%), hemorrhagic (5.3%) or mixed forms (5.3%). Using the Paris II score, 53% were non-responders to UDCA, and only 26% achieved a good biochemical response. Regarding immunosuppressive therapy, transaminase normalization occurred in just 21%, with the majority showing persistent inflammatory activity. Two patients died, and two were listed for liver transplantation. <h3>Conclusion</h3> PBC-AIH overlap syndrome is an uncommon but clinically aggressive and histologically advanced condition. Our findings highlight the diagnostic complexity, frequent association with other autoimmune diseases, and the suboptimal therapeutic response, especially to immunosuppressants. These results reinforce the need for early recognition, personalized therapeutic strategies, and specialized follow-up, particularly in resource-limited settings, to improve patient outcomes.