Leukemoid reaction resulting from granulocyte colony-stimulating factor producing urothelial carcinoma of the renal pelvis.

Leukemoid reaction is defined as a reactive leukocytosis in response to infection, inflammation, or therapeutic agents such as growth factors and malignancy. We report a case of leukemoid reaction resulting from granulocyte colony-stimulating factor producing urothelial carcinoma of the renal pelvis as evidenced on immunohistochemical analysis.