Autoimmune hepatitis type 2 associated with an unexpected and transient presence of primary biliary cirrhosis-specific antimitochondrial antibodies: a case study and review of the literature
1 Center for Autoimmune Liver Diseases, Humanitas Clinical and Research Center, Via Manzoni 56, 20089, Rozzano(MI), Italy
2 Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis, Davis, CA, USA
3 Clinical Laboratory, Ospedali Riuniti, Bergamo, Italy
4 Institute of Liver Studies, King’s College London School of Medicine at King’s College Hospital, Denmark Hill Campus, London, UK
5 Department of Medicine and Transplantation, Ospedali Riuniti, Bergamo, Italy
6 Department of Surgical and Gastroenterological Sciences, University of Padova, Padova, Italy
7 Center for Liver Research (CeLiveR), Ospedali Riuniti, Bergamo, Italy
8 Division of Pediatrics, Ospedali Riuniti, Bergamo, Italy
9 Department of Pediatrics, Federico II University, Naples, Italy
BMC Gastroenterology 2012, 12:92 doi:10.1186/1471-230X-12-92Published: 20 July 2012
Unlike other autoimmune liver diseases, primary biliary cirrhosis (PBC) has never been reported in early childhood, while type 2 autoimmune hepatitis (AIH) is eminently a paediatric disease.
We describe a case of type 2 AIH with serological positivity for PBC-specific anti-mitochondrial antibodies (AMA) in a 3-year old girl. We found this observation intriguing as AMA and indeed an overlap with PBC are virtually absent in Type 2 AIH, a pediatric form of AIH which is distinct precisely because it is characterized by pathognomonic anti-liver kidney microsomal type 1 (LKM-1) showing a remarkable antigen-specificity directed against cytochrome P4502D6. We also review the literature in relation to AMA positivity in paediatric age and adolescence. In our case, the presence of AIH-2-specific anti-LKM-1 and PBC-specific AMA was confirmed by indirect immunofluorescence (IIF), and immunoblotting and ELISA based on recombinant mitochondrial antigens. The clinical, laboratory and histological features of the child are given in detail. Interestingly the mother was AMA positive without other features of PBC. The child was successfully treated with immunosuppression and five years after the original diagnosis is on a low dose of prednisolone and azathioprine, with no signs of relapse. Anti-LKM-1 antibodies are still present in low titres. AMA were detectable for the first 4 years after the diagnosis and disappeared later.
This is the first case report in the literature of AIH type 2 with an unexpected PBC-specific AMA positivity in a young child. Response to immunosuppressive treatment was satisfactory and similar to that described in AIH. A review of published reports on AMA positivity in paediatric age shows that the antibody may arise in the context of immunodeficiency and is variably associated with liver damage.