Ref:Textbook of pathology (Harsh mohan) 6th edition,page no.492 Overexposure to asbestos is associated with 3 types of lesions: asbestosis, pleural disease and ceain tumours. A. ASBESTOSIS. The gross pulmonary fibrosis caused by asbestos exposure and histologic demonstration of asbestos bodies on asbestos fibres is termed asbestosis. Grossly, the affected lungs are small and firm with cailage-like thickening of the pleura. The sectioned surface shows variable degree of pulmonary fibrosis, especially in the subpleural areas and in the bases of lungs . The advanced cases may show cystic changes. Histologically, the following changes are observed: 1. There is non-specific interstitial fibrosis. 2. There is presence of characteristic asbestos bodies in the involved areas . These are asbestos fibres coated with glycoprotein and haemosiderin and appear beaded or dumbbell-shaped. The coating stains positively for Prussian blue reaction. 3. There may be changes of emphysema in the pulmonary parenchyma between the areas of interstitial fibrosis. 4. The involvement of hilar lymph nodes in asbestosis is not as significant as in silicosis. B. PLEURAL DISEASE. Pleural disease in asbestos exposure may produce one of the following 3 types of lesions: 1. Pleural effusion. It develops in about 5% of asbestos workers and is usually serious type. Pleural effusion is generally accompanied by subpleural asbestosis. 2. Visceral pleural fibrosis. Quite often, asbestosis is associated with dense fibrous thickening of the visceral pleura encasing the lung. 3. Pleural plaques. Fibrocalcific pleural plaques are the most common lesions associated with asbestos exposure. Grossly, the lesions appear as circumscribed, flat, small (upto 1 cm in diameter), firm or hard, bilateral nodules. They are seen more often on the posterolateral pa of parietal pleura and on the pleural surface of the diaphragm. Microscopically, they consist of hyalinised collagenous tissue which may be calcified so that they are visible on chest X-ray. Asbestos bodies are generally not found within the plaques. C. TUMOURS. Asbestos exposure predisposes to a number of cancers, most impoantly bronchogenic carcinoma and malignant mesothelioma . A few others are: carcinomas of oesophagus, stomach, colon, kidneys and larynx and various lymphoid malignancies. 1. Bronchogenic carcinoma is the most common malignancy in asbestos workers. Its incidence is 5 times higher in non-smoker asbestos workers than the nonsmoker general population and 10 times higher in smoker asbestos workers than the other smokers. 2. Malignant mesothelioma is an uncommon tumour but association with asbestos exposure is present in 30 to 80% of cases with mesothelioma. The exposure need not be heavy because mesothelioma is known to develop in people living near asbestos plants or in wives of asbestos workers.