Malignant pleural mesothelioma presenting as acute empyema with severe leukocytosis.

Five months after the treatment for acute empyema, a 75-year-old woman was referred to our hospital because of marked elevation of the white blood cell (WBC) count and C-reactive protein (CRP) level, and a right pleural mass detected by chest computed tomography. At this time, the WBC count and CRP level had increased to 60400/microl and 18.2 mg/dl, respectively. We performed biopsy and the tumor was diagnosed as sarcomatoid malignant pleural mesothelioma. Malignant pleural mesothelioma occasionally presents the symptoms and findings like an acute empyema. We demonstrated the case of malignant pleural mesothelioma which had presented the symptoms and laboratory findings very similar to acute empyema and had treated as acute empyema.