RT Journal Article SR Electronic T1 Malignant mesothelioma: incidence, asbestos exposure, and reclassification of histopathology. JF British Journal of Industrial Medicine JO Br J Ind Med FD BMJ Publishing Group Ltd SP 39 OP 45 DO 10.1136/oem.41.1.39 VO 41 IS 1 A1 W E Wright A1 R P Sherwin A1 E A Dickson A1 L Bernstein A1 J B Fromm A1 B E Henderson YR 1984 UL http://oem.bmj.com/content/41/1/39.abstract AB The Los Angeles County Cancer Surveillance Program abstracts records on almost all cases of cancer occurring in the county. In a study of those cases of pleural and peritoneal malignant mesothelioma (MM) that occurred from 1972 to 1979 occupational histories were obtained during interviews, and histopathology of the tumours was reviewed and classified by a member of a mesothelioma reference panel who was unaware of the exposure histories. About half the cases reviewed had likely exposure to asbestos at work. The greatest proportion of cases designated as MM by the pathologist occurred among individuals likely to have had the heaviest exposure of asbestos (42%). No upward trend of incidence over time was apparent among cases designated as MM. The age adjusted incidence rates for designated MM were lower than in other studies. The well recognised interobserver variability in diagnosing MM apparently produces raised estimates of incidence and an overestimate of trends of incidence. The interobserver variability may result from different awareness of MM occurrence, a lack of precise histopathological criteria for the diagnosis, or the influence of a history of exposure to asbestos on the interpretation. A history of exposure to asbestos may bias interpretation of histopathology and should not be used to make the histological diagnosis.