Question: I have a patient who for unrelated reasons underwent a CAT scan of the chest. The radiologist's report mentions some "subpleural scarring which is probably chronic." My question is, how do I know this is not a condition like IPF and what do I do with this information?

Answer: This is not an uncommon scenario. As more CAT scans of the chest are obtained, unsuspected findings crop up. Radiologists are very attentive to nodules that might herald an underlying carcinoma, and usually recommend appropriate follow-up in their reports. Unfortunately, similar vigilance is often not applied to changes consistent with scarring which are often assumed to be benign. Some of these cases may be early IPF, which has a prognosis similar to that of lung cancer. In this particular case, without seeing the CAT scan, there is no way to know if the changes are consistent with early IPF or not. Indeed, data on what "early IPF" looks like on CAT scan are lacking. Most of our studies and hence definition of a "typical" CAT scan for IPF are based on populations that have included patients with some degree of honeycombing in the lungs. However, radiographic honeycombing usually correlates pathologically with advanced fibrosis and may not be observed earlier in the disease course. It is also important to consider the whole clinical picture, including age, functional status and the presence or absence of any comorbidities.