Asbestosis Guidelines

Updated: Mar 05, 2020
  • Author: Christopher D Jackson, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Guidelines Summary

In 2014, an update to the 1997 consensus Helsinki guidelines for the diagnosis of asbestos-related disorders was published. The guidelines define asbestosis as diffuse interstitial fibrosis of the lung as a consequence of exposure to asbestos dust. The following criteria should be used to identify asbestos exposure [1] :

  • Over 0.1 million amphibole fibers (>5 μm) per gram of dry lung tissue, or

  • Over 1 million amphibole fibers (>1 μm) per gram of dry tissue, as measured by electron microscopy in a qualified laboratory, or

  • Over 1,000 asbestos bodies per gram of dry tissue (100 asbestos bodies per gram of wet tissue), or

  • Over 1 asbestos body per milliliter of bronchoalveolar lavage fluid, as measured by light microscopy in a qualified laboratory.

The guidelines recommend the use of computed tomography (CT) imaging in the diagnosis of asbestos-related diseases under the following circumstances:

  • A borderline finding of lung fibrosis (International Labor Office [ILO] 0/1-1/0) is detected;

  • There is a discrepancy between a lung function finding of restriction and radiographs interpreted as normal;

  • Widespread pleural changes severely hamper the radiographic visibility of the lung parenchyma.

The criteria for diagnosis of asbestosis on CT scans include:

  • Sum grade of ≥2–3 bilateral irregular opacities in the lower zones according to the reference film, or

  • Bilateral honeycombing (sum grade ≥2) would be sufficient to represent fibrosis, according to the ICOERD system (International Classification of high-resolution CT [HRCT] for Occupational and Environmental Respiratory diseases classification).

The guidelines further note that in histopathology, bronchiolar wall fibrosis has been associated with asbestos exposure and other exposures including smoking. Subpleural curvilinear lines or dots in HRCT are findings of bronchiolar fibrosis. [1]