Asbestosis
ASBESTOS RELATED DISEASES
INTRODUCTION
- Asbestos is a family of proinflammatory crystalline hydrated silicates that are associated with pulmonary fibrosis, carcinoma, mesothelioma, and other cancers.
- There are two distinct geometric forms of asbestos:
- Serpentine chrysolite – most of the asbestos used in industry
- Amphibole (crocidolite)
- Both serpentine and amphibole can cause all asbestos related diseases except for mesothelioma, which is usually associated with amphibole (crocidolite).
- Aspect (length-to-diameter) ratio decides carcinogenicity. Amosite & crocidolite are relatively malignant, whereas anthophyllite, chrysotile and tremolite are benign
- Asbestos exposure may occur in asbestos industry, ship building & textile .
ASBESTOS RELATED DISEASES CONSIST OF :
- Lower lobe fibrosis
- Localized fibrous plaques which may be calcified.
- Diffuse pleural fibrosis.
- Pleural effusion.
- Pseudotumor(Round Atelactasis)
- Parenchymal interstitial fibrosis (asbestosis).
- Lung carcinoma → Most common neoplasm associated with asbestos exposure.
- Asbestosis and smoking act synergistically to cause lung cancer
- Mesothelioma of pleura and peritoneum → most specific neoplasm associated with asbestos exposure.
- Predilection for Lower Zone
- (Whole lung may be involved with predominant lower zone involvement)
- Ascites.
- Laryngeal and other extrapulmonary neoplasms including colon cancer
INVESTIGATIONS IN A CASE OF ASBESTOS RELATED DISEASES
- Chest x-ray often reveals hyperinflation of the normal parenchyma leading to “honeycombing.”
- Asbetosis may present with thickening or calcification along the parietal pleura, particularly along the lower lung fields, the diaphragm, and the cardiac border(Shaggy heart) on x ray.
- HRCT (investigation of choice) shows subpleural pulmonary arcade, pleural based nodular irragularities, parenchymal bands & septal lines.
- Round atelectasis occurs mostly in peripheral, lower, dorsal (posterior) lobes adjacent to visceral pleura and presents with Comet taiVVaccum cleaner/ Crow’s feet sign and Swiss cheese air bronchogram.
- Histology:
- Ferruginous bodies represent foreign inorganic or organic fibers coated by complexes of iron and glycoproteins.
- While ferruginous bodies are most commonly seen in asbestosis they are not diagnostic because it may be seen in other type ofpneunoconiosis.
- When asbestos fiber is coated by iron and glycoprotein, this ferruginous body is called asbestos body-characteristic of asbestosis.
- Ferruginous bodies are best seen in section that have stained for iron with prussion blue.
- Microscopically ferruginous bodies give a Shikh Kebab appearance.
- Asbestos bodies seen in sputum.
CHARACTERISTICS OF ASBESTOS RELATED DISEASES
- The disease does not usually appear until 5-10 years of exposure.
- Once established, the disease is progressive even after removal of the worker from contact.
- It is a notifiable disease under Factory’s act 1948 and Indian Mines act 1952 in India along with silicosis, byssinosis etc
Exam Question
- Asbestosis is asssociated with lung cancer and Ascites.
- Asbestosis is associated with extensive pleural thickening and calcification especially involving the diaphragmatic pleura.
- Ferruginous bodies are commonly seen in Asbestosis.
- Asbestosis is associated with the following pulmonary manifestations: Mesotheliomas ,Pneumoconiosis,Calcified pleural plaques , Diffuse pulmonary interstitial fibrosis,Progression of lesion even after stopping exposure to asbestos ,Honeycombing,Basal peribronchial fibrosis, Asbestos bodies in sputum,Nodular lesions involving lower lobe.
- There are six types of asbestos; one is serpentine (chrysotile) and five are fibrous amphiboles (amosite, crocidolite, anthophyllite, tremolite, and actinolite).
- The most likely diagnosis in a 35 year old roofer presenting with complain of dyspnea and chronic dry cough and Chest x-ray revealing pulmonary hyperinflation with “honeycombing” and calcified parietal pleural plaques is Asbestosis.
- The probable diagnosis in a 48 years old man, resident near a textile mill presenting with respiratory symptoms, X Ray chest showing – fine reticular & nodular pattern in lower zone with loss of clarity of diaphragm & cardiac shadows and the presence of small pleural effusion is Asbestosis.
- Asbestosis does not usually appear until 5-10 years of exposure.
- Asbestosis may be associated with peritoneal Mesothelioma.
- Asbestosis and smoking act synergistically to cause lung cancer.
- Asbestosis is a notifiable disease under Factory’s act 1948 in India.
- Asbestosis causes shaggy heart borders.
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