Overlap syndromes in autoimmune liver disease: a review

Self-directed immune-mediated injury to hepatocytes and cholangiocytes results in autoimmune liver disease (AILD). AILD comprises three distinct entities: autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC) and each of these autoimmune conditions has distinct phenotypic, serological, radiologic and laboratory findings. AIH is characterized by injury to the hepatocytes while PBC and PSC occur due to injury to bile ducts. Although, these are considered rare diseases, it is important to note that some patients can present with features characteristic of more than one AILD, and these conditions are described as overlap syndromes (OS). Currently, there is lack of data regarding the epidemiology of OS. Majority of the data regarding the epidemiology of OS comes from single-center and small studies. The clinical features of OS are similar to the underlying AILD. There is also no consensus on how to manage patients with OS and the management is dependent on treating the underlying AILDs. Management of PBC involves use of ursodeoxycholic acid (UDCA), while management of AIH involves the use of steroids and immunosuppressants. In this article, we will review the current literature on various OS and their respective diagnostic criteria. This article will also discuss epidemiology, clinical features, prognosis as well as outcomes among patients with various OS.