Granulocyte colony stimulating factor-producing diffuse malignant mesothelioma of pleura

We report the rare case of a 61-year-old man with a diffuse malignant mesothelioma of mixed subtype which produced granulocyte colony-stimulating factor (G-CSF). The white blood cell (WBC) was elevated to 85,100/mm3 without any evidence of infection, and the G-CSF level in the pleural effusion was also increased at 13,200 pg/ml. The lobes of the lung were encased in a tumor. Histopathologically, the tumor cells were of a polymorphous morphology with an epithelial and sarcomatoid mixed pattern. Immunohistochemistry showed that the tumor cells were positive for vimentin, cytokeratin, epithelial membrane antigen, thrombomodulin, and G-CSF, and negative for carcinoembryonic antigen (CEA), CD34, and surfactant apoprotein-A.