Trilineage response to granulocyte colony-stimulating factor administration in a patient with myelodysplastic syndrome.

We report a 72-year-old man with refractory anemia with excess of blasts who presented severe pancytopenia and pneumonia and received granulocyte colony-stimulating factor (G-CSF) treatment over a 6-week period. In addition to a dramatic increase in mature neutrophils, platelet count and hemoglobin level, the patient achieved a hematological remission which continued for more than 5 months despite discontinuation of the treatment. This observation confirms that in some cases during G-CSF treatment erythropoiesis and thrombopoiesis may improve in addition to the expected effect on neutrophils. While the patient remained in hematological remission, bone marrow examination revealed trilineage dysplasia. This finding suggests that the hematological remission in this patient may not have resulted from a recovery of non-clonal hematopoiesis of a normal clone, but may have derived instead from the monoclonal hematopoiesis of a neoplastic clone.