An unusual histiocytoid proliferation in infancy

A 2 1/2-month-old female infant was admitted to the Hôpital Ste-Justine for investigation of marked hepatosplenomegaly. The pregnancy and neonatal period were uneventful and the child had exhibited normal growth. There were no skin or osseous lesions. Investigations revealed a coagulopathy with hypoproteinemia, but normal liver enzymes. An open liver biopsy revealed widespread infiltration of portal veins and hepatic sinusoids by large histiocyte-like cells, exhibiting protein S-100 and Ia antigen, but negative for OKT6, peanut agglutinin, and T and B cell and macrophage markers. Ultrastructural examination failed to reveal Birbeck granules. After a 4-month course of chemotherapy, liver and spleen size decreased, the biochemical profile returned to baseline levels, and the child has remained well. A repeat liver biopsy, performed at the end of the therapeutic trial, was normal. This patient presents an unusual pattern of infiltration of liver and spleen not readily classifiable within the present scheme of histiocytic disorders.