The association of pulmonary CMV infection with interstitial pneumonia after bone marrow transplantation. Histopathological and immunohistochemical findings in 104 autopsies.

Lung tissue of 104 necropsies was studied by routine (HE) histology, by immunohistochemistry and partly by in situ hybridization in order to explore the association of pulmonary cytomegalovirus (CMV) infection and interstitial pneumonia (IP) after allogeneic bone marrow transplantation. IP was detected in 59 of 104 patients (56%). 12 of these (20% of the IP cases) presented as CMV-IP. No evidence of a CMV infection was obtained in the remaining 47 IP. Immunohistochemistry did not improve the CMV detection essentially over the results of routine (HE) analysis of viral inclusions. In situ hybridization performed on frozen sections of 21 cases turned out to be more sensitive than routine histology and immunohistochemistry, detecting active as well as latent CMV infections. However, the clinical relevance of latent infections, as disclosed by positive hybridization results in the absence of nuclear inclusions as well as immunohistochemical positivities, seems to be low, because latent infections typically were not found to be associated with IP.