Carcinosarcoma of the gallbladder producing α-fetoprotein and manifesting as leukocytosis with elevated serum granulocyte colony-stimulating factor: Report of a case

A 69-year-old man was referred to our hospital for investigation of leukocytosis and a persistent fever of 38°C, but we could find no evidence of a specific infection. The leukocyte count was 18 000/mm 3 , and the serum granulocyte colony-stimulating factor (G-CSF) and α-fetoprotein (AFP) levels were both elevated, at 66.3 pg/ml and 1,495 ng/ml, respectively. Computed tomography (CT) showed a gallbladder tumor and we performed extended cholecystectomy. Postoperatively, the fever subsided and the leukocyte count, serum G-CSF and AFP level normalized. Histologically, the tumor was a carcinosarcoma of the gallbladder. Immunohistochemical staining of the tumor cells was positive for AFP, but negative for G-CSF. This is the first report of a carcinosarcoma of the gallbladder producing AFP. The laboratory findings and clinical course strongly suggested that the tumor produced not only AFP, but also G-CSF.