Liver involvement in childhood histiocytic syndromes.

The histiocytic syndromes of childhood are disorders of the reticuloendothelial system with variable clinical manifestations. Included among them are Langerhans cell histiocytosis and hemophagocytic lymphohistiocytosis. This discussion will be restricted to these two disorders. Liver disease in these conditions is common. Langerhans cell histiocytosis is characterized by the abnormal clonal proliferation of the macrophage-derived Langerhans cell. Liver involvement at diagnosis has management and prognostic significance. In a subgroup of patients, sclerosing cholangitis develops, which may lead to end-stage liver disease requiring liver transplantation. Hemophagocytic lymphohistiocytosis is a disease of abnormally activated macrophages that can involve multiple organ systems, including the liver. Differentiation between this disorder and other causes of pediatric liver disease is critical, because treatment strategies include chemotherapy, immunosuppression, and frequently bone marrow transplantation.