Paraneoplastic granulocyte colony-stimulating factor secretion in soft tissue sarcoma mimicking myeloproliferative neoplasia: a case report

Background While paraneoplastic leukocytosis is a common phenomenon in solid tumors, extreme elevations of white blood counts (WBC) in the range of more than 100,000/μl are uncommon in patients with non-hematologic malignancies. Leukocytosis with mature neutrophils due to a granulocyte colony-stimulating factor (G-CSF) producing tumor is only seen on rare occasions.