An Overview of Interstitial Lung Disease

Lisa H. Lancaster, MD: Interstitial lung disease is a rare but not uncommon disease of scaring or inflammation that occurs in a space, or potential space, between the Avella and the capillaries or blood vessels. So this is a unique area that’s very important for gas exchange to occur, and especially oxygenation.

Interstitial lung disease is becoming more prevalent with time. We’re probably diagnosing it more often as we have better imaging modalities that are picking out more subtle interstitial changes in patients. There are over 200 different interstitial lung diseases that are out there. So as we’re trying to evaluate and diagnose the patient with particular interstitial lung disease, we’re trying to be detectives and getting clues from the history, physical, and laboratory and imaging assessment along with clues from the family and the patient and their family histories and trying to put the pieces together to be able to formulate a diagnosis as best we can.

Alicia M. Hinze, MD: Progressive fibrosing-insterstitial lung disease is describing an interstitial lung disease that, as the name would suggest, has progressive features of fibrosis over time. So the classic progressive fibrosing- interstitial lung disease would be the idiopathic pulmonary fibrosis. This is kind of the classic one that is associated with progressive fibrosis. However, there are other subsets of interstitial lung disease that also share some similar characteristics in that they will go on to have progressive fibrosis. So, in patients with autoimmune disease, for example, and I’ll use scleroderma as that’s probably one of the most frequent autoimmune diseases that we do see interstitial lung disease in the context of, there will be a subset of patients that have interstitial lung disease that may not progress. But then there’s also the subset of patients with interstitial lung disease that will progress. So the ones that are developing progressive fibrosis by high resolution CT, as well as increasing restrictive lung disease by pulmonary function testing, these are sort of the category of patients that can be defined or thought about in the sense that they have progressive fibrosing lung disease.

Idiopathic pulmonary fibrosis, that is a lung disease in which, has a progressive fibrosing phenotype, but it’s not associated or driven by perhaps an autoimmune process or any other exposure such as environmental exposures or precipitated by any other really features. It’s occurring as it would suggest, idiopathically. So there’s not an underlying driver for the lung disease that can be identified by history. And so it kind of is this group of lung diseases, again that shows as progressive fibrosis. And we don’t have necessarily an underlying cause for it.

Systemic sclerosis with interstitial lung disease can be somewhat, it can change by definition. So, if we’re looking strictly at whether there’s interstitial lung disease by high resolution CT, we can actually see that there may be some bibasilar interstitial changes on high res CT in about 65 to 90 percent of patients, depending on the subset of patients that we’re looking at. However, not all interstitial lung disease is going to progress to causing physiologic changes. So there are patients that we can see a little bit of bibasilar interstitial fibrosis, but we may not see any changes on pulmonary function testing. So, on pulmonary function testing, this is really helping us understand what physiologic lung changes are being caused by the actual fibrosis itself.

Lisa H. Lancaster, MD: Pulmonologists are key and central figures in the management and diagnosis of interstitial lung disease. Other key players in the diagnosis and ultimate team players in the management are primary care physicians because they may be the first ones to actually pick up the diagnosis, find the interstitial lung disease, and coordinate the care with the local pulmonologists, or interstitial lung disease center.

Alicia M. Hinze, MD: In patients with interstitial lung disease that are coming for, perhaps this is their initial evaluation, rheumatologists will see these patients often in the context of either 1) a question of whether they might have an autoimmune disease underlying the interstitial lung disease. Sometimes they will come in in the setting of having some positive autoantibodies and the rheumatologist is again asked to determine whether there may be an underlying autoimmune disease that may be driving some of the interstitial lung disease process. This is particularly important as there are some patients that may have a pattern of disease that we call nonspecific interstitial pneumonitis. And these patients, if it’s in the context of an autoimmune disease, may respond to immunosuppressant therapies.