Differentiation between Pleural Mesothelioma versus Pseudo-Mesothelioma Demonstrated in Eight Autopsy Cases

The pleural lobes are the origin of different pathologies, including malignant tumors, e.g., pleural mesothelioma. In some cases, clinical and macroscopic presentation point strongly to the diagnosis but often enough the patient has another underlying disease; malignant neoplasms of the lung as well as other organs (skin, pancreas, prostate or kidney) can mimic pleural mesothelioma and if so, are defined as ‘pseudo-mesothelioma’. We present eight cases that are clinically and macroscopically highly suspicious for pleural mesothelioma. All patients were autopsied due to medico-legal issues and work-related diseases. Six out of eight patients underwent autopsy to exclude possibility of asbestos-related malignancy and two out of eight due to exclusion of silicosis. From the eight cases, only three were real pleural mesotheliomas. Another three were adenocarcinomas of the lung mimicking pleural mesotheliomas. One had squamous cell carcinoma of the lung. Lastly, one patient had an extraordinary case of papillary renal cell carcinoma metastasizing universally in both pleura lobes. Due to striking morphological similarities, the exact final diagnosis was only possible after extended immunohistochemical analysis of the tissues. In summary, not only is it difficult to distinguish between real or pseudo pleural mesothelioma in patients having had contact with asbestos. Even patients with no evidence of asbestos contact can have clinical and pathological events strongly suggesting asbestosis and mesothelioma, without having it.