Histopathology of the liver in histiocytosis syndromes.

Liver biopsies were studied in 47 cases representing various histiocytosis syndromes. These included 32 cases of hemophagocytic syndrome, 11 cases of Langerhans cell histiocysis (LCH), and 4 cases of other histiocytic disorders. All cases of hemophagocytic syndrome, except one with cytomegalovirus infection, displayed portal lymphohistiocytic infiltrates dominated by T lymphocytes. Activation of the hepatic mononuclear phagocytic system (MPS), evidenced by enlarged von Kupffer cells, some of which were hemophagocytic, was seen in 28 cases of hemophagocytic syndrome. Endothelial enlargement, minor degrees of hepatocellular degeneration, and steatosis were also noted. Ten of the 11 cases of LCH also showed activation of the MPS. It was the only lesion in two biopsies. Seven cases demonstrated nonspecific "triaditis." In three this was associated with cholangiocentric and random acinar histiocytic lesions. Evidence of activation of the MPS was also observed in both cases of Rosai-Dorfman disease and was accompanied by acinar histiocytic lesions in one and triaditis in the other. Likewise, both cases of juvenile xanthogranuloma showed activation of the MPS and focal granulomatous lesions. It is concluded that activation of the MPS is a common feature of liver disease in histiocytosis syndromes and that hepatic enlargement may be the result of this process instead of, or in addition to, the liver lesions known to be featured in these disorders. Hepatic lesions of the various histiocytosis syndromes resemble typical lesions in other sites and, in some instances, are accompanied by nonspecific changes. These nonspecific changes may occur in the absence of lesions that are diagnostic or typical of the particular histiocytosis syndrome. The location and character of hepatic lesions are important factors in the significance of liver involvement.