In this context, proper diagnosis should take advantage of immunohistochemical panels with several markers in order to exclude serous histotype as well as mesothelial tumors such as malignant mesothelioma and papillary mesothelioma which are usually positive for Calretinin, WT1, and keratin 5/6, contrary to what is observed in CCC. This evidence concerns the gene KRT5 and malignant mesothelioma.