RESUMEN
An 80-year-old man presented with abdominal fullness and vomiting. Laboratory data revealed severe anemia, an inflammatory response, and elevated white blood cell counts. Abdominal computed tomography indicated ileus caused by a jejunal tumor measuring 8cm in diameter. Although small-bowel endoscopy enabled visualization of the tumor, adequate biopsy specimens could not be obtained for accurate diagnosis. The patient's condition rapidly deteriorated, because of which surgical treatment could not be initiated. The patient died approximately 3 weeks after admission. High serum granulocyte colony-stimulating factor (G-CSF) levels were detected at autopsy. Immunohistochemical staining of the autopsy specimen indicated positive G-CSF levels in the jejunal tumor. On the basis of these findings, a final diagnosis of undifferentiated carcinoma of the jejunum producing G-CSF was made.