1. Diagnostic Specialties Laboratory, Bremerton, Washington 98310, USA.
Background: We report a series of 196 cases of pseudomesotheliomatous neoplasms identified in one of our laboratories between 1983 and 2015. We also performed an extensive review of the literature. Most "pseudomesotheliomas" arise in the pleural tissue of the chest cavity and resemble pleural mesotheliomas, macroscopically and histologically, although some metastasize to the pleura from another site or can metastasize to other parts of the body.
Methods: The criteria for inclusion as a pseudomesotheliomatous neoplasm were: 1) presentation of the tumor as a diffuse pleural neoplasm confirmed radiographically, by video-assisted thoracoscopy, by thoracotomy, or at autopsy; 2) lack of a tumor outside of the lung/chest cavity; and 3) the microscopic, histologic, histochemical, immunohistochemical, and/or ultrastructural features of the neoplasm other than a mesothelioma, or a neoplasm other than a mesothelioma that showed histologic, histochemical, immunohistochemical features of a specific neoplasm.
Results: Of the 196 patients in our series, 183 were primary in the lung, 2 were primary in the peritoneum, and 11 were metastatic from another site. One hundred thirty-four (68.3%) had a known history of exposure to asbestos (130 occupational and 4 bystander/paraoccupational). Six (6) had no history of exposure to asbestos; and in 56 cases, the exposure history was unknown. Of the 196 cases, 109 (55%) had a history of cigarette smoking, 23 were nonsmokers, and in 64 cases the smoking history was unknown. Of the 196 cases of pseudomesotheliomatous neoplasms arising in the lung/pleura and peritoneum, 134 (68.3%) had historical exposure to asbestos in the workplace or as a result of paraoccupational and/or bystander exposure; 100 (51%) had radiographic and/or pathologic evidence of pleural plaques or pathologically definable asbestosis; and 56 of 59 cases evaluated for ferruginous bodies and/or asbestos fibers had above background levels in digested lung tissues.
Conclusions: We conclude there is a relationship between the development of pseudomesotheliomatous lung cancer and asbestos exposure based on radiological/pathological findings (including tissue burden of ferruginous bodies and/or uncoated asbestos fibers) as correlated with a background history in many individuals within this study.
Keywords: Pseudomesotheliomatous lung cancer, asbestos, cigarette smoke, asbestosis, fiber analysis