Pors J, et al. - Experts investigated expression of cyclin D1 nuclear staining in two tissue microarrays comprising reactive epithelial mesothelial proliferations (n = 52), reactive spindle cell mesothelial proliferations (n = 51), epithelial mesotheliomas (n = 54), and sarcomatous/desmoplastic mesotheliomas (n = 22). It was discovered that for epithelial mesothelial proliferations, the finding of > 50% of tumor cells staining encourages a diagnosis of epithelial mesothelioma with 100% specificity however only with moderate sensitivity (57%).