The Common Pneumoconioses

Silicosis

Exposure to silica from mining of coal, graphite, iron, tin, uranium, gold, silver, copper

After silica particles are ingested by alveolar macrophages, breakdown of macrophage releases enzymes which produce fibrogenic response
Silicosis has a progressive nature despite cessation of dust exposure
X-ray picture is of multiple small rounded opacities

Eggshell calcification of hilar nodes in 5%
Caplan’s syndrome consists of large necrobiotic nodules superimposed on silicosis
Silicosis predisposes to TB

Coal Workers’ Pneumoconiosis (CWP)

Originally silica was erroneously thought to be the cause of CWP
Actually mostly due to the inhalation of pure carbon
Still referred to as anthrasilicosis or anthracosis although most coal in USA is bituminous
Coal dust is deposited in the alveolar macrophages which migrate to, and leave, coal dust deposits around the respiratory bronchiole

Complicated CWP occurs as large masses in either the upper lobes or the superior segments of the lower lobes

Unlike silicosis, the large upper lobe lesions of CWP are single (rather than conglomerate) black masses with a liquid core, not a fibrous tissue core
The masses may undergo cavitation either from TB or ischemia
The rounded opacities of CWP, found predominantly in the upper lobes
Do not progress in the absence of more coal dust

Classification is by the International Labor Organization’s 1980 classification (p,q,r, etc.)
There is a direct correlation between the amount of coal dust contained in the lungs and the profusion category

Asbestosis

Salts of salicic acid
90% of asbestos in the USA is white asbestos (chrysotile) occurs in automotive workers, shipfitters, construction workers
Asbestos particles invoke a hemorrhagic response in the lung

Fibers are then coated with a ferritin-like material resulting in ferruginous bodies
Does its damage in respiratory bronchioles and alveoli

Affects lower lobes first
Opacities are small and irregularly shaped
Cardiac silhouette may become shaggy
Almost all patients have some pleural involvement-pleural plaque, diffuse pleural thickening, calcification or effusion
Pleural involvement without parenchymal disease is common
Parietal pleural plaques in the mid lung are the most common asbestos-related disorder and are usually bilateral
Pleural calcification occurs in about 50% with asbestos-related disease, especially diaphragmatic pleura
Diffuse pleural thickening involves diaphragmatic pleura, blunting of costophrenic sulci and lateral chest wall thickening
Effusion alone may occur early in the disease (first 20 years) in about 3% of cases
Asbestos-related lung cancer is either squamous cell or adenocarcinoma
Bronchogenic ca is almost always associated with cigarette smoking
Mesotheliomas most often due to crocidolite particles
Mesotheliomas are not related to cigarette smoking
In contrast to silicosis, hilar lymph nodes are rarely affected

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