CSF3 and neoplasm: The diagnostic criteria for GPT are: (i) severe leukocytosis mainly due to mature granulocytes in the peripheral blood; (ii) elevation of serum G-CSF levels; (iii) normalization of leukocytosis and serum G-CSF after tumor resection or treatment; and (iv) histological evidence of a G-CSF-producing tumor by immunohistochemistry.