Pulmonary leukostasis mimicking pulmonary embolism.

We report a case of a 32-year-old woman who presented with shortness of breath and pleuritic chest pain, and mismatched perfusion defects on a ventilation-perfusion scan suspicious for pulmonary embolism. However, subsequent data revealed the diagnosis of acute myelogenous leukemia with hyperleukocytosis and associated pulmonary leukostasis. Unfortunately, the patient died despite urgent leukopheresis. Autopsy examination revealed extensive infiltration of leukemic cells in all major organs with no evidence of pulmonary embolism. This case highlights the clinical, radiographic and histologic features of pulmonary leukostasis, and reminds the clinician that not all ventilation-perfusion mismatching is due to thromboembolic disease.