Undetected viral infection in diffuse alveolar damage associated with bone marrow transplantation

To investigate the presence of nondiagnosed viral lung infections in patients who developed acute respiratory failure and diffuse pulmonary infiltrates after bone marrow transplantation (BMT), we studied necropsy-obtained lung specimens with features of diffuse alveolar damage (DAD) where no other specific histological diagnosis could be established, by using in situ hybridization and immunohistochemistry. Lung tissue samples obtained at necropsy from 19 patients (12 males and 7 females; 31 +/- 11 yrs mean +/- SD age) who died 56 +/- 36 days after BMT (12 allogeneic and 7 autologous), were studied retrospectively using specific deoxyribonucleic acid (DNA) probes to detect cytomegalovirus (CMV), herpes simplex virus (HSV), Epstein-Barr virus (EBV), and adenovirus genomes. Tissue samples were additionally processed with antibodies to CMV and HSV antigens. Cells infected by CMV were detected by in situ hybridization in five cases, and by immunohistochemistry in four cases. Combining the results of both procedures, a previously undiagnosed CMV infection was found in six patients. All of them had received an allogeneic BMT and had developed graft-versus-host disease (GVHD). No evidence of cells infected by HSV, EBV, or adenovirus was found in any case. No viral infection was detected either in recipients of autologous marrow or in recipients of allogeneic BMT without GVHD. These results indicate that pulmonary cytomegalovirus infection not detected by conventional histological examinations may be present in patients with diffuse alveolar damage associated with bone marrow transplantation, especially in recipients of allogeneic marrow who develop graft-versus-host disease. Furthermore, the use of in situ hybridization and/or immunohistochemistry on pulmonary histology might improve the diagnosis of viral lung infections in patients receiving bone marrow transplantation.