Learning Radiology xray montage
 
 
 
 
 

Common Pneumoconioses
Silicosis, Coal Worker's Pneumoconiosis, Asbestosis

Silicosis

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

    • Also iron and steel foundry workers, sand blasters

  • 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

  • Imaging picture is of multiple small rounded opacities

    • Usually in the upper lobes

    • May occasionally calcify (20%)

    • Lymph node enlargement is common

    • Large opacities are conglomerations of small opacities

  • Progressive Massive Fibrosis (PMF)

  • Cavitate from tuberculosis or ischemic necrosis

  • 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 anthrosilicosis 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

    • Here a very small fibrous reaction occurs

  • 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

    Asbestosis

Asbestosis. There are multiple pleural plaques, some calcified, some not (white arrows). There are also small, irregularly-shaped desnities in the lung parenchyma (red circles)

  • 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