How is asbestos lung disease diagnosed?

There must be a history of substantial exposure to friable asbestos AND a lung condition that could be related to asbestos exposure AND no evidence for another cause. For example, a positive exposure history plus interstitial lung disease on chest x-ray plus the absence of any other cause, would be a presumptive diagnosis of asbestosis. However, note that:

* A history of asbestos exposure, without a documented lung condition related to asbestos exposure = no diagnosis of asbestos-related disease. Example: A 65-year-old man with a history of asbestos exposure and a previously clear chest x-ray suddenly develops pulmonary edema (water in the lungs); his pulmonary condition is not one related to asbestos exposure.

* No history of asbestos exposure, with a condition that could otherwise be due to inhaled asbestos = no diagnosis of asbestos-related disease. Example: A 45-year-old woman with no history of asbestos exposure develops malignant mesothelioma. This pulmonary condition is commonly linked to asbestos exposure, but absent such history the cause in her case remains unknown.

The vast majority of asbestos lung diseases occur from remote exposure at the workplace. Given a documented history of asbestos exposure, there are three ways to diagnose asbestos lung disease:

* A chest x-ray or chest CT scan (more detailed than a regular chest x-ray) diagnostic of or consistent with an asbestos-related condition.
* A lung biopsy diagnostic of an asbestos-related condition.
* An autopsy diagnostic of an asbestos-related condition.

Well over 95% of cases can be diagnosed with just the history of friable asbestos exposure and an abnormal chest x-ray or chest CT scan. It is rare to make the diagnosis using lung tissue or autopsy, because these exams are rarely obtained.

Obtaining a portion of lung tissue usually requires surgery. While tiny pieces of lung tissue can be obtained without surgery (through an instrument called a bronchoscope), they are usually too small to diagnose asbestos-related diseases. When lung tissue is available the pathologist will look for ferruginous bodies (see What are ferruginous bodies?) as well as other signs of asbestos-related pathology. Surgical removal of lung tissue obviously presents some risk to the patient, and won't be attempted unless there is perceived benefit. For example, since asbestosis is not treatable, physicians won't recommend an operation if they strongly suspect only this condition. On the other hand, a patient may have surgery to remove a lung cancer, and then there will be sufficient lung tissue to also look for asbestosis.

Autopsy is even rarer than operation for lung tissue, because most diagnoses are made while the patient is living. Also, the vast majority of deaths are no longer autopsied in this country. In fact, most families of asbestos-exposed workers refuse permission, even though an autopsy, because it allows for complete examination of both lungs, would definitively make the diagnosis if the disease is present.