[Histopathological findings of pulmonary complications in 16 patients who received allogeneic hematopoietic stem cell transplants].

Pulmonary complications are frequent and sometimes lethal in allogeneic hematopoietic stem cell transplantation recipients. In our hospital, 16 transplanted patients had pulmonary complications at post-mortem examination. We review the patients' clinical courses and histopathological findings of their lungs, and discuss the factors related to the onset of the pulmonary complications. In 16 patients, 10 had infectious lung diseases and the other 6 were non-infectious. Five of the patients with infectious diseases had fungal infections: 2 aspergillosis, 2 candidiasis and 1 mucormycosis. In the other 5, 2 had cytomegalovirus pneumonia, 1 had herpes simplex virus pneumonia and 2 had bacterial pneumonia. These ten patients were highly immunocompromised because of steroid therapy or neutropenia. The histopathological diagnosis of all 6 patients with non-infectious disease was diffuse alveolar damage (DAD). Most of the DAD patients were also complicated with other organ damage due to regimen-related toxicity (RRT), and their respiratory symptoms had appeared during the rapid tapering off of their immunosuppressant drugs. These results revealed that prevention of fungal infection was still important for highly immunocompromised patients. Efforts to reduce RRT such as using a reduced intensity regimen and careful tapering off of immunosupressants are expected to lead to a decrease in non-infectious pulmonary complications.