Morphologically, mesotheliomas may be composed of epithelial and/or sarcomatous elements with various patterns, such as tubular, papillary, tubulopapillary, and diffuse epithelial or mixtures of these. Two cases are described in which, in addition to typical mesothelioma, there was cartilage with foci of calcification and ossification, and fibrochondrosarcomatous tissue. These foci were intimately associated with the mesothelioma, which suggested that they formed an integral part of the tumour. One of the cases also showed a cuff of cartilage and bone round blood vessels and bronchioles in the lung parenchyma. The pathogenesis could be explained if the mesothelial cell is considered to be totipotent and able to give rise to epithelial and connective tissue elements. Other theories that must be considered are: that there are two separate neoplasms; that there is a circulating substance, perhaps induced by the mesothelioma, which stimulated the cartilage and bone formation; and that the cartilage and bone were due to a previous or associated infection such as tuberculosis. Calcification is also common in asbestotic pleural plaques. Case 1A 35-year-old black woman was admitted to hospital with generalised slight oedema and lumps under the skin of the left chest. These were attached deeply but were not adherent to skin. Grossly distended superficial neck veins were present. The patient had lived in the Kuruman area of 37' the NW Cape Province but no history of asbestos exposure could be elicited. She died soon after admission. At necropsy both parietal and visceral pleural layers of the left lung were grossly thickened and infiltrated by neoplasm that had also invaded the pericardium and left leaf of the diaphragm. In parts the growth was "boney" in consistency. Over the right lung there were a few adhesions but no other significant changes were noted. The liver was grossly enlarged and had a nutmeg appearance.The hilar glands were slightly enlarged and slightly pigmented but not fibrosed. The bronchi and pulmonary vessels showed no gross changes. The left lung was encased in neoplasm up to about 2 cm thick, and calcification was present in this tissue (fig 1). A few metastatic neoplastic deposits were present in the right lung, which also! contained a focus of encapsulated necrosis 3 mm in diameter. The epicardium contained a few metastatic neoplastic deposits.On microscopy, sections of the encapsulated necrosis showed the features of active fibrocaseous tuberculosis. The lung tissue showed no evidence of asbestosis, and ferruginous bodies were not on 11 May 2018 by guest. Protected by copyright.

A computerized system for recording the results of structured, numerically coded autopsy reports on various types of mine workers has been in operation at the National Centre for Occupational Health in Johannesburg since 1975. Historical developments, particularly those associated with compensation for occupational disease, have resulted in very high autopsy rates, especially among whites. Since its inception, the pathology automation (PATHAUT) system has accumulated the results of more than 33,000 autopsies. The data set is described in the hope of stimulating interest in the possible uses of the data and encouraging collaborative research. Some characteristics of the database with potential research implications are discussed. These include differing age and work patterns for blacks and whites and geographic factors with potential influence on whether a body or only the cardiorespiratory organs are sent for examination.

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Ten out of 12 South African baboons (Papio ursinus) survived exposure to amosite asbestos dust for periods ranging from 242 days to 898 days at an aerosol level ranging between 1,100 and 1,200 fibers per milliliter. After exposure, they were kept under observation until they died; the total residence time of amosite varied from 1.2-10.2 years. All underwent detailed postmortem necropsy examinations. All baboons had asbestosis. Five of the baboons developed malignant diffuse mesothelioma; three peritoneal, and two pleural with peritoneal invasion. These results indicate that amosite is highly carcinogenic. Since it is difficult to accomplish follow-up of persons exposed to amosite asbestos because of the geographic location of the amosite mines and mills in South Africa (a majority of the workers being migrant laborers from countries bordering on the Transvaal), it is therefore probable that cases of peritoneal mesothelioma have been missed. If human beings are likely to react to amosite as do baboons, epidemiological follow-up should include identification of abdominal as well as thoracic neoplasms.