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. The gene discussed is CALB2; the disease is mesothelial neoplasm.