Document r6m69wRQOLjkNdQ19kywZXOpG

! U ' .1. ;> 32 S.A. Medical Journal 14 January 1961 14 Jenuari special INVESTIGATIONS Radiological Features The X-ray findings roughly parallel the clinical progress. The initial radiographs may show few changes. In about a third of the cases, radiological 'signs of asbesiosis were present. Asbestosis. in' individuals with a proved and ade quate record of exposure, is characterized by evidence of diffuse interstitial fibrosis of varying degree. In a wellestablished case the appearance will conform to the wellknown classical pattern of pulmonary asbestosis. This may be either a generalized homogenous clouding of the lung fields, particularly the lower zones, or a fine striate and fibrillary change in the lung structure, with progressive loss of pulmonary radiolucency (Fig. 3). In the majority of cases of asbesiosis, nld-standing pleuritic changes are also seen. Thus a combination of both pleural and pulmonary parenchymal pathology fre quently occurs. The pleural changes take the form of bi lateral pleural thickening, pleural adhesions and rather characteristic dense calcific plaques (Frost et al.u). While pleural thickening per ee in asbestosis is non-specific in character, sclerotic pleurisy, with plaque formation, con stitutes a readily recognizable and rather typical entity (Fig. 4). The pattern of calcification patently differs from mica (Smith1*), The plaques may be few or widespread. They are usually bilateral, and disposed in irregular patches, chiefly in the middle and lower zones. Seen endon they appear as linear plaques in. the periphery, along the diaphragmatic contours, and adjacent to the media stinum. A lateral view of the thorax will also very often show extensive linear plaque formation, involving the diaphragm and the anterior aspect directly behind the sternum. Such pleural calcification was encountered in several of our cases of mesothelioma (Hurwitz*'-"). However, in the majority of cases, no evidence of pre ceding pleural or pulmonary asbestosis was found. These cases, on investigation, invariably showed unilateral pleurBl involvement in the form of diffuse thickening or effusion. The appearance may be massive from the beginning, but usually a localized scalloping, or solitary mass in the periphery, raises the first suspicion of pleural neoplasm. As the disease advances,- more extensive nodular or `lumpy' pleural thickening develops (Fig. J). This pattern Pig. 6. h involvem- is still p Fig. 4. Extensive bilateral pleural plaque formalion. Typi cal involvement of paramediastinal and diaphragmatic pleura is also demonstrated. pleural calcification due to other causes. This patient was recognized frequently during the recent investigations of miners and millers. Even the chance finding of such typical calcification is now accepted as being highly sig nificant, so that previous' exposure to asbestos may be predicted with reasonable confidence. The dense- plaques, however, do simulate those described in. workers exposed to other silicate dusts such as tremollte talc, calcimine- and of unilateral pleural pathology is a highly significant find- . ing in a patient from the asbestos areas, but of course, a similar appearance may be produced by secondary-malig nant involvement of the pleura. Very often a large pleural effusion will obliterate the picture and, only after removal of the fluid, will it become apparent that the pleura is ` grossly thickened and nodular. Both the parietal and - ' visceral pleura are affected and an induced pneumothorax, : particularly, will clearly demonstrate the rather character- ' istic pattern of marginal massive nodularity. along the : parietal chest wall, over the surface of the collapsed lung, / and at the base (Fig. fi). In the I cavity may may remai lung may ' by a thick astinal pie come infill logically. 1 extension, progressivi a change also occui may be pi Stout a ponderanc ported by present at had righttouis proc of the pat Thoraeon The ini appoinlin; thelioma lated. Wb walls of t no archie the tecbn of area I obtain a usual din