Criteria
Asbestosis is a type of pneumoconiosis that presents as diffuse interstitial fibrosis of the lung following exposure to asbestos fibres.[1][2]
Chest x-rays are classified and scored according to the International Classification of Radiographs of Pneumoconioses developed by the International Labour Organization (ILO).[3] In the US, the assessing physician must have passed a test on classifying radiographs, which is administered by the National Institute for Occupational Safety and Health (NIOSH), and must be retested every 5 years.[24]
Technical quality of radiographs
Good
Acceptable, with no technical defect likely to impair classification
Acceptable, with some technical defects but still adequate for classification
Unacceptable for classification
Assessment of parenchymal abnormalities
Small parenchymal abnormalities (longest dimension ≤10 mm) are described by profusion, affected zones of the lung, shape (rounded or irregular) and size.
Profusion:
Refers to the concentration of small opacities in affected lung zones
Categories: 0, 1, 2, and 3
Always appear with a subcategory as 0/-, 0/0, 0/1; 1/0, 1/1, 1/2; 2/1, 2/2, 2/3; 3/2, 3/3, or 3/+
Affected zones:
Each lung field is divided into three zones (upper, middle, lower).
If there is a marked difference in profusion between zones, only those showing the greatest degree of profusion are used to classify overall profusion.
Shape and size:
Rounded small opacities (diameter):
p: up to 1.5 mm
q: 1.5 to 3.0 mm
r: 3.0 to 10.0 mm
Irregular small opacities (width):
s: up to 1.5 mm
t: 1.5 to 3.0 mm
u: 3.0 to 10.0 mm
Large parenchymal opacities (longest dimension >10 mm) are described as one of three categories:
Category A: One large opacity with longest dimension up to 50 mm, or several large opacities with the sum of their longest dimensions up to 50 mm.
Category B: One large opacity with longest dimension >50 mm, but not exceeding the equivalent area of the right upper zone; or several large opacities with the sum of their longest dimensions >50 mm, but not exceeding the equivalent area of the right upper zone.
Category C: One large opacity with the longest dimension exceeding the equivalent area of the right upper zone, or several large opacities that when combined exceed the equivalent area of the right upper zone.
Assessment of pleural abnormalities
Pleural plaques (localised pleural thickening)
Recorded as absent or present.
Site, calcification, and extent of pleural plaques are recorded for all sites, and separately for the right and left lungs.
Costophrenic angle obliteration
Recorded as absent or present, separately for the right and left lungs.
Obliteration may occur without diffuse pleural thickening.
Diffuse pleural thickening
Recorded as absent or present along the chest wall.
In-profile or face-on, and extent recorded separately for the right and left lungs.
Pleural thickening at the apex of the lung only is not generally recorded as pleural thickening.
Pleural abnormalities, typical of asbestos fiber inhalation, include plaques that may or may not be calcified, diffuse pleural thickening, benign pleural effusions, or rounded atelectasis. These may occur with or without parenchymal fibrosis.[1]
Criteria for diagnosis of non-malignant disease related to asbestosis[1]
Evidence of structural change via x-ray imaging of lungs or histology from lung biopsy
Evidence of plausible causation via an occupational or environmental history of significant exposure with the appropriate latency, or of a marker of exposure such as pleural thickening or increased asbestos mineral fibre in lung or bronchial lavage fluid; and
Exclusion of alternative diagnoses.
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