Occludin positivity was most seen in adenocarcinomas (37.5-100%) and in neuroendocrine neoplasms (67.9-100%), slightly less frequently in squamous cell carcinomas (23.8-93%) and in malignant mesotheliomas (up to 48.1%) and only rarely in non-Hodgkin’s lymphomas (1-2%) and in most mesenchymal tumors. The gene discussed is OCLN; the disease is malignant mesothelioma.