small cell mesotheliomaspindle cell mesotheliomamesothelioma small cell lung cancermalignant mesothelial cellsepithelial mesotheliomaepithelioid mesotheliomapleural mesotheliomamesothelial cells in peritoneal fluidmesothelioma pleural effusionmalignant pleural mesotheliomapleural mesothelioma stagespleural mesothelioma life expectancy