Syndrome associated with high numbers of immature leukocytes in the peripheral circulation.
Symptoms non-specific and include shortness of breath, headache, confusion, impaired sensorium and focal neurological deficits.
Death can occur within hours and mortality rates may be as high as 40%.
Usually associated with a high and rapidly increasing blast count of greater than 100,000/mL.
Symptoms can occur with white blood cell counts a low as 50,000 mL.