Thrombocytosis in patients with malignant pleural mesothelioma.

Thrombocytosis above 40.0 X 10(4)/mm3 occurred in five of six (83%) patients with malignant mesothelioma. In contrast, the incidence of thrombocytosis was 7.5% in patients with lung adenocarcinoma, 12.5% in squamous cell carcinoma, 5.1% in small cell carcinoma, and 41.7% in large cell carcinoma, respectively. The platelet count in large cell carcinoma was significantly higher than that in other cell types of lung cancer; however, the platelet count in malignant mesothelioma was much higher than that in large cell carcinoma. These results show that the incidence of thrombocytosis seems to be high in malignant mesothelioma, although the mechanism is thus far unknown.