Glioblastoma causing granulocytosis by secretion of granulocyte-colony-stimulating factor

We describe a patient with a glioblastoma multiforme with excessive granulo cytosis in the peripheral blood. Shown at both protein and mRNA levels, the tumor produced very high levels of granulocyte-colony-stimulating factor ( G-CSF). G-CSF is a growth factor that induces the recruitment of granulocyt es. The paraneoplastic phenomenon described here partly mimicked a brain ab scess. Production of G-CSF by (brain) tumor cells might be related to the g ranulocytosis common in malignant disease.