Clinicopathological study of liver involvement in cytomegalovirus infection in infant autopsy cases

To clarify the pathogenesis of hepatic cytomegalovirus (CMV) infection, we clinicopathologically investigated 18 infants and 10 adults with cytomegalic inclusion bodies (CIB) in the liver among a total of 75 autopsy cases with CIB in any organ of the body. CMV infection was confirmed by immunohistochemistry and in situ hybridization. When CIB were present in the liver, CMV infection also tended to be systemic. All the adults were immunocompromised patients, but diseases inducing immunodeficiency were present in only two of the infants. The severe and systemic CMV infections we found in infants might have been associated with congenital CMV infection. Histotogically, hepatocyte necrosis, cholestasis, extramedullary hematopoiesis and fatty degeneration were more frequent and prominent in infants than in adults. However, inflammatory cell infiltration was only slight. In addition, the frequent association with premature birth and hypoplasia of the thymus suggested that insufficient development of immunity may result in hepatic CMV involvement in infants. CIB were most frequently observed in hepatocytes in both infants and adults, but in infants they were also frequently seen in the bile duct epithelium. These histopathological findings and the high incidence of jaundice in infant patients suggest that the bile duct is also an important site of CMV proliferation in infants, and that CMV infection may be one cause of infantile jaundice.