Leiomyosarcoma in the humerus with leukocytosis and elevation of serum G-CSF

Leukocytosis associated with secretion of granulocyte colony-stimulating factor (G-CSF) has been reported in various tumors, primarily poorly differentiated epithelial tumors, but is extremely rare in bone tumors. An 84-year-old woman experienced swelling and pain in the shoulder for 1 month. Leukocytosis and elevated serum G-CSF were observed, but resolved following tumor resection. A diagnosis of leiomyosarcoma of the bone with expression of G-CSF was confirmed immunohistochemically. Histological diagnosis of leiomyosarcoma showed it to be differentiated, which is unusual for G-CSF-secreting tumors.