What does biapical or bibasilar lung scarring mean on a CT or X-ray?

Usually not. In a 2024 study of 780 adults who had a chest CT at outpatient centers, radiologists found scarring at the top of the lungs on 65% of them. In more than half of those it was mild, under 5 millimeters thick, and it was usually even on both sides. In that group it wasn't linked to lung cancer.

Chest X-rays show it getting more common with age. In a study of 28,727 people having routine health checks, a thickened lining of the lung, mostly at the top, was the most common abnormal finding. It showed up in 1.8% of teenagers, 4.1% of people in their 40s and 9.8% of people 60 and older. People who were tall and thin, and people who smoked or used to, had it more often.

So 'mild biapical scarring' on its own describes something a great many adults have. What makes it worth a closer look is what comes with it: breathlessness or a cough that won't go away, a scar that's grown since the last scan, or the fibrosis words in the table above.

Often no single cause is ever found. Radiopaedia, a reference radiologists use, says these caps become more common with age, and that the top of the lung getting less blood flow over the years is the favored explanation for most of them.

Other causes it lists are an old infection at the top of the lung, with tuberculosis the classic one, and radiation treatment to the chest. If you had TB, a bad pneumonia as a child, or radiation for breast cancer or lymphoma, mention it. It helps the doctor read the scar as old.

One version is worth a call rather than a wait. Scarring at the top of just one lung, with new shoulder or arm pain on that side, is something your doctor will want to look at more closely, because a rare tumor at the lung's top can cause exactly that pain.

'Bibasilar' means at both lung bases, the bottom of each lung just above the diaphragm. 'Bibasilar scarring' means the radiologist sees healed scar tissue there, usually as thin lines. 'Linear' or 'band-like' describes that shape.

Reports often say 'atelectasis or scarring' at the bases, because the two can look the same on one picture. Atelectasis is lung that didn't fully inflate and can open again. A scar stays. Radiopaedia notes that small linear scars tend not to clear on later scans, so an older scan usually settles it. Our guide to bibasilar atelectasis covers that side.

The bases are also where fibrosis often starts, which is why the words next to 'scarring' matter more here than at the top. The Fleischner Society, a society of chest radiologists, doesn't count a mild finding in one spot, or on one side only, as an early fibrosis sign. A few thin lines that match your last scan are the ordinary kind.

Radiologists now have a name for early signs of fibrosis found by chance: interstitial lung abnormalities. In the Fleischner Society's 2020 position paper, that means changes in someone not suspected of having lung disease that cover more than 5% of at least one zone of the lung. They show up in 4% to 9% of older smokers and 2% to 7% of older non-smokers.

The words that point that way are 'reticulation' or 'reticular opacities' (a fine net of lines), 'traction bronchiectasis' (airways pulled wider by the scar around them), 'honeycombing' (small clustered air spaces) and 'subpleural' (just under the lung's outer edge), especially in the lower lobes. The paper calls the kind with distorted lung plus pulled airways or honeycombing 'fibrotic', and says those are the changes most likely to spread over time.

Even then, it's a reason for tests, not a verdict. The paper advises sending people with symptoms, abnormal breathing tests or changes in three or more zones to a lung specialist. If your report uses these words, ask whether you need lung function tests, and whether you should see a doctor who treats interstitial lung disease, the group of illnesses that scar lung tissue.

For decades, doctors have described lung cancers found next to a scar. But a 2020 study of 917 people with lung cancer in the African Journal of Thoracic and Critical Care Medicine points out that most cancers can make scar tissue of their own, so it's hard to prove the scar came first.

For the most common kind, the study of 780 chest CTs in step 1 found no link between this scarring and lung cancer.

What lowers the worry most is the same check as everywhere else on this page: a scar that hasn't changed since an older scan. A new spot, a growing one, or a nodule named separately in the report is a different finding, and it gets its own follow-up.