Pathogenesis of massive pulmonary hemorrhage in acute leukemia.

Massive pulmonary hemorrhage is an uncommon complication of leukemia and is generally attributed to thrombocytopenia. However, a platelet deficiency cannot be the entire explanation, since most patients with thrombocytopenia never experience this complication. To better define the reason for intra-alveolar bleeding, we studied the clinical and pathologic findings in three patients with leukemia who died of massive pulmonary hemorrhage. Although the major finding at autopsy in all three cases were widespread intra=-alveolar hemorrhage, evidence of diffuse alveolar damage was also found. In one patient, a lung biopsy specimen (obtained five days before death) showed extensive intra-alveolar hemorrhage by light microscopy, while severe destruction of alveolar walls was detected by electron microscopy. The findings suggest that diffuse alveolar damage plus thrombocytopenia are necessary for massive pulmonary hemorrhage to occur in leukemia.