Pulmonary cytolytic thrombi: unusual complication of hematopoietic stem cell transplantation.

Pulmonary complications of hematopoietic stem cell transplantation (HSCT), including peripheral blood stem cell transplantation (PBSCT) and bone marrow transplantation, are frequent and often life-threatening. Differentiating acute infectious from noninfectious pulmonary complications is difficult but critical for proper treatment. The authors describe an 11-year-old boy who developed a sudden fever and cough associated with a normal chest radiograph 2 months after successful haploidentical PBSCT for severe aplastic anemia. High-resolution chest computed tomography revealed numerous tiny peripheral pulmonary nodules. Lung biopsy demonstrated an unusual occlusive thrombotic vascular lesion associated with hemorrhagic infarction without evidence of infection. The thrombi were composed of intensely basophilic granular material recently described as "cytolytic" thrombi. Symptoms and chest computed tomography improved rapidly following intravenous corticosteroids and cyclosporin. However, the patient subsequently died of rapidly progressive pulmonary hypertension. Our patient illustrates the importance of considering this noninfectious complication in the acute pulmonary disorders associated with HSCT as this condition may represent a pulmonary manifestation of acute graft-versus-host disease.