Nouveaux concepts dans l’hémochromatose périnatale

Relevance of C5b9 immunostaining in the diagnosis of neonatal hemochromatosis

BACKGROUND

Neonatal hemochromatosis caused by a gestational alloimmune mechanism or gestational alloimmune liver disease (GALD) is a rare perinatal disorder characterized by intra- and extrahepatic iron overload. It is believed to result from complement-mediated liver injury, in which the classical complement pathway is activated by maternal antibody/fetal antigen complexes, leading to hepatocyte lysis by the membrane attack complex C5b9. According to some authors, C5b9 expression in more than 75% of liver parenchyma is specific for GALD.

METHODS

We conducted a retrospective multicentric immunohistochemical study with anti-C5b9 in GALD cases (n = 25) and non-GALD cases with iron overload (n = 36) and without iron overload (n = 18).

RESULTS

C5b9 was expressed in 100% of GALD cases but involved more than 75% of the liver parenchyma in only 26% of the cases. C5b9 was detected in 26.75% of the non-GALD cases with more than 75% of positive parenchyma in maternal erythrocytic alloimmunization, herpes and enterovirus hepatitis, bile acid synthetic defect, DGUOK mutation, Gaucher disease, cystic fibrosis, and giant-cell hepatitis with autoimmune hemolytic anemia.

CONCLUSION

Diagnosis and therapeutic management of GALD cannot only be based on C5b9 expression in liver samples as it is not specific of this disease.

Transient neonatal liver disease after maternal antenatal intravenous Ig infusions in gestational alloimmune liver disease associated with neonatal haemochromatosis

OBJECTIVES

Neonatal haemochromatosis is a rare gestational disease that results in severe foetal liver disease with extrahepatic iron overload, sparing the reticuloendothelial system. Recurrence can be prevented with intravenous immunoglobulin (IVIG) infusions during pregnancy, supporting an alloimmune aetiology. The aim of the study was to assess the effect of antenatal treatment with IVIG infusion on the outcome of pregnancies in women with a history of documented neonatal haemochromatosis likely owing to gestational alloimmune disease and to analyse IVIG tolerance.

METHODS

From 2004 to 2012, 8 pregnant women were treated with IVIG at 1 g/kg body weight weekly from 18 weeks' gestation until birth in a prospective multicentre study.

RESULTS

All 8 neonates born to the treated women survived. Five developed mild neonatal liver disease with hepatomegaly (n = 1), hyperechogenic liver (n = 2), abnormal liver function tests (n = 1), raised serum ferritin (n = 3) and α-fetoprotein (n = 5) levels, or mild iron overload on liver magnetic resonance imaging (n = 1). Ferritin and α-fetoprotein levels normalised before 14 days and 2 months, respectively. A per-mother-basis analysis comparing outcomes of treated (n = 8) and untreated (n = 9) gestations showed a significant improvement in the survival of neonates with gestational IVIG therapy (survival 8/8 vs 0/9, P < 0.001). Adverse effects of IVIG infusion occurred in 5 mothers leading to discontinuation of treatment in 1 case. Preterm neonates born before 37 weeks' gestation had a decreased risk of neonatal liver disease (P = 0.04).

CONCLUSIONS

Antenatal treatment with IVIG infusion in women at risk for gestational alloimmune disease recurrence improves the outcome of pregnancies despite mild signs of transient neonatal liver disease.

French retrospective multicentric study of neonatal hemochromatosis: importance of autopsy and autoimmune maternal manifestations

Neonatal hemochromatosis is a rare disease that causes fetal loss and neonatal death in the 1st weeks of life and is one of the most common causes of liver failure in the neonate. The diagnosis is mostly made retrospectively, based on histopathologic features of severe liver fibrosis associated with hepatic and extrahepatic siderosis. Several etiologies may underlie this phenotype, including a recently hypothesized gestational alloimmune disease. Fifty-one cases of liver failure with intrahepatic siderosis in fetuses and neonates were analyzed retrospectively. Maternal and infant data were collected from hospitalization and autopsy reports. All available slides were reviewed independently by 3 pathologists. Immunologic studies were performed on maternal sera collected immediately after delivery. The diagnosis of neonatal haemochromatosis was retained in 33 cases, including 1 case with Down syndrome and 1 case with myofibromas. Liver siderosis was inversely proportional to fibrosis progression. In fetuses, iron storage was more frequent in the thyroid than in the pancreas. Perls staining in labial salivary glands was positive in 1 of 5 cases. Abnormal low signal intensity by magnetic resonance imaging was detected in the pancreas in 2 of 7 cases. Renal tubular dysgenesis was observed in 7 of 23 autopsy cases. Chronic villitis was seen in 7 of 15 placentas. Half of the mothers presented with an autoimmune background and/or autoantibodies in their sera. Our work highlights the importance of autopsy in cases of neonatal hemochromatosis and marshals additional data in support of the hypothesis that neonatal hemochromatosis could reflect maternal immune system dysregulation.