Un cas de cirrhose néonatale sans surcharge en fer : hépatite alloimmune congénitale

Abstract

Background. Fetal liver disease is a rare antenatal disorder for which etiology is frequently unknown. Recently, congenital alloimmune hepatitis emerged as a major cause of antenatal liver disease. Its typical presentation can be as a severe neonatal liver failure with hepatic and extrahepatic iron overload, a clinical state called neonatal hemochromatosis. Methods. A pregnant woman was investigated for heterogeneous fetal hepatomegaly. Pregnancy was also complicated by fetal alloimmune thrombocytopenia. The newborn presented at birth with liver cirrhosis and mild liver dysfunction. Follow-up until 36 months showed progressive normalization of all liver parameters. All metabolic and infectious analyses were negative. Liver biopsy showed severe hepatitis with post-necrotic fibrosis and regenerative nodules. There was no iron overload. To search for immune injury, paraffine sections of the liver biopsy were stained with an antibody against the membrane attack complex (MAC, anti human c5b-9, Peter Whitington’s Lab, Children’s Memorial Hospital, Chicago, IL), the terminal complement cascade neoantigen occurring specifically in complement activation by the IgG-mediated classical pathway, and which is responsible for cell death. Results. Strong immunostaining against MAC-antigen was found in the liver of the patient, with 90% of target hepatocytes whereas in a control group of patients with other neonatal liver diseases, it was 10.8±12.5%. Because IgG in neonates originate only from the mother, it signs the alloimmune nature of the disease. Conclusion. For a long time, pathophysiology of neonatal hemochromatosis remained unsolved. Recently, it was elucidated as congenital alloimmune hepatitis. With this case, we expend the recognized clinical spectrum by showing that congenital alloimmune hepatitis can present as milder cases, without iron overload. It should be considered as a cause of unexplained neonatal liver disease, even in the absence of siderosis. Such diagnosis is of great importance regarding the necessity of immunotherapy in further pregnancies in order to avoid recurrence of alloimmune injur