Granulocyte colony-stimulating factor-producing lung cancer and acute respiratory distress syndrome.

Granulocyte colony-stimulating factor (G-CSF)-producing lung cancers are known to cause extreme leukocytosis. However, acute respiratory distress syndrome (ARDS) caused by G-CSF-producing lung cancer is extremely rare. We present a case of G-CSF-producing lung cancer with marked leukocytosis, which rapidly led to severe ARDS after the patient developed pneumonia. The present case suggests that extreme leukocytosis may easily lead to ARDS, triggered by infection. Thus, G-CSF-producing lung cancer with marked leukocytosis should be carefully monitored before surgery and during treatment.