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

We describe a patient with a glioblastoma multiforme with excessive granulocytosis 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 granulocytes. The paraneoplastic phenomenon described here partly mimicked a brain abscess. Production of G-CSF by (brain) tumor cells might be related to the granulocytosis common in malignant disease.