[A Case of Granulocyte-Colony Stimulating Factor-Producing Undifferentiated Sarcoma of the Transverse Colon].

We report a case of granulocyte-colony stimulating factor(G-CSF)-producing undifferentiated sarcoma of the transverse colon. A 80-year-old woman was referred to our hematology department after visiting her primary physician with chief complaints of decreased appetite and fatigue. An elevated white blood cell count was observed during examination. Further laboratory tests at our hospital revealed an elevated white blood cell count of 95,800/μL and a plasma G-CSF level of 895 pg/mL. The patient was referred to our department after a tumor lesion was found in the transverse colon during computed tomography, and a G-CSF-producing tumor was suspected. Right hemicolectomy was performed for diagnosis and treatment. Pathological examination revealed an undifferentiated sarcoma, and immunostaining results were positive for G-CSF, leading to a diagnosis of a G-CSF-producing undifferentiated sarcoma of the transverse colon.