Asbestosis other diagnostic studies


 * Associate Editor(s)-In-Chief: Kim-Son H. Nguyen, M.D., M.P.A., Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA,

Pulmonary function test
Pulmonary function tests are not diagnostic, but provide a measure of pulmonary function.


 * Most patients demonstrate a restrictive pattern with reduced lung volumes, particularly with reduced vital capacity and reduced total lung capacity, and reduced pulmonary compliance.


 * Reductions in diffusing capacity are common.


 * Some patients may show obstructive patterns, but rarely without associated tobacco exposure. Airflow limitation in these patients may be due to inflammation of large airways, resulting from asbestos deposition along the respiratory bronchioles.


 * Exudative pleural effusions may develop. These usually occur within 15 years of exposure.  These may resolve spontaneously, and may leave visceral pleural thickening and blunting of the costophrenic angle, and can even impair pulmonary function in some cases.


 * Hyaline plaques may form on the parietal pleura, and may calcify. These may develop after less exposure than required for asbestosis, and are therefore more common, occurring in up to 50% of patients with asbestos exposure.

Biopsy
Bronchoalveolar lavage or biopsy may be necessary for diagnosis in some cases.
 * Path shows coated or uncoated asbestos fibers in association with pulmonary fibrosis
 * Asbestos bodies are asbestos fibers surrounded by a coating of iron and protein. Other fibers such as talc, glass, carbon, etc, may also be coated in such a manner, producing “ferruginous bodies”.  Electron, but not light, microscopy can differentiate the central fiber.
 * Quantity of asbestos fibers correlates with the degree of fibrosis.