Monocytic leukemoid reaction, glucocorticoid therapy, and myelodysplastic syndrome.

A leukemoid reaction is a complex and poorly understood response by the bone marrow to a variety of stresses; although any peripheral blood cell line may be involved, it is rarely a purely monocytic event. A case is reported of a true monocytic leukemoid reaction in a patient with myelodysplastic syndrome related to the effect of corticosteroids on the underlying marrow disorder.