Honeycombing on a CT report: lung scarring, and how doctors find its cause

The words next to it

Words you may see beside honeycombing on a report, and what each one changes.

Fibrotic interstitial lung disease (ILD)

The umbrella name for conditions that scar the tissue around the lung's tiny air sacs. It names a group of diseases, not one.

Probable UIP

The same outer-edge, lower-lung scarring, with reticulation and traction bronchiectasis but no honeycombing.

Indeterminate for UIP

Fine scar lines and ground-glass haze, with no honeycombing and no traction bronchiectasis.

Alternative diagnosis

The radiologist reads the scan as looking more like a different kind of lung disease than UIP.

New or increased honeycombing

On a repeat scan, one of the signs doctors use to judge that the scarring is progressing.

How a lung team works out the cause

A UIP pattern is the hallmark of IPF, scarring with no cause found. But the same pattern turns up with fibrotic hypersensitivity pneumonitis, connective tissue disease and lung disease from exposures, and on CT they often look the same. So before anyone says IPF, the lung specialist (pulmonologist) rules out other causes, using other tests and sometimes other specialists.

Breathing tests (lung function tests) measure how much the scarring is affecting the lungs now. Repeated over time, they show whether it's stable or worsening, and an absolute drop in forced vital capacity (FVC, how much air you can blow out) of 5% predicted or more within a year is one sign of progression.

The case may also go to a multidisciplinary discussion, where lung doctors and radiologists review the scan and history together. Guidelines let that team diagnose IPF from a probable UIP pattern without a lung biopsy, when the rest of the picture fits.

How serious honeycombing is, and what treatment does

In a large study across several scarring lung diseases, people whose CT showed honeycombing had a higher death rate than people without it, and honeycombing marked a disease that tends to progress, much like IPF.

If the diagnosis is already IPF, that same study found honeycombing added no extra risk. IPF tends to progress with or without it.

"There is currently no cure for IPF", and treatment aims to slow the lung damage and help quality of life. Two medicines, nintedanib and pirfenidone, can help the lungs work better. When scarring from another disease keeps progressing despite the usual treatment, guidelines suggest nintedanib.

Questions to ask the doctor

• Is this a UIP pattern or a probable UIP pattern, and does that change what happens next?
• Radiologists only moderately agree on spotting honeycombing. Has a chest radiologist or a lung disease team looked at my CT?
• What could be causing the scarring in my case, and what will you check to rule things out?
• When are my breathing tests, and how often will we repeat them?
• Is there an older CT to compare this one with, to see whether the honeycombing is new?

Often on the same report

• Pulmonary fibrosis

  The tissue deep in the lungs has become scarred, thick, and stiff, which makes it harder to breathe and get oxygen. Causes include pollutants, some medicines, and connective tissue diseases. In most cases no cause is found, which is called idiopathic pulmonary fibrosis.

• Interstitial lung disease

  A group of conditions where the tissue around the lungs' tiny air sacs becomes inflamed, stiff, or scarred, so the sacs can't expand as well. Causes include autoimmune diseases, certain medicines, chest radiation, and workplace dusts, and sometimes no cause is found.

• Reticular opacities

  A pattern of lines in the lung on the X-ray or CT. It has many causes, from fluid or a recent infection to longer-term scarring from old infection, dust exposure, autoimmune disease, or certain medicines.

• Bronchiectasis

  Some of the larger airways in the lungs have been damaged and are permanently wider than normal. It's often caused by airway inflammation or infection that keeps coming back, and sometimes it starts after a severe lung infection in childhood.

• Lung scarring

  Old scar tissue in the lung or its lining. At the very top of the lungs, sometimes called an apical cap, it becomes more common with age and usually comes from scarring of the lining or lung tissue, sometimes after an old infection like TB.

• Ground-glass opacity

  A hazy area on the CT where the lung looks cloudier than normal, but the airways and blood vessels can still be seen through it. Many things can cause it, including infection, fluid, inflammation, scarring, and sometimes cancer.

Questions people ask

Why does honeycombing occur in the lungs?

As scarring takes hold, the thin walls between the lung's tiny air sacs collapse into scar, and the smallest airways stretch open into small cysts. Honeycombing is the CT name for those cysts clustered together.

Which diseases cause honeycombing?

Several scarring lung diseases, not only IPF. In one large study, honeycombing showed up on CT in 42% of people with chronic hypersensitivity pneumonitis, 42% with lung disease tied to connective tissue disease, 38% with IPF and 29% with unclassifiable or other types.

Is honeycombing the same as lung scarring?

Yes, it's a form of it. Radiologists treat honeycombing and traction bronchiectasis as the two signs that confirm fibrosis (lung scarring) is really there. Our lung scarring guide covers the other forms scarring takes on a report.

What's the difference between honeycombing and bronchiectasis?

Honeycombing is a cluster of small cysts, about 3 to 10 mm across with thick walls, usually right at the outer edge of the lung. Bronchiectasis means airways that are wider than normal. When a report says traction bronchiectasis, scar tissue is pulling those airways open, and it often appears beside honeycombing.

Other phrases explained: Pulmonary nodule · Ground-glass opacity · Aortic atherosclerosis · Schmorl's node · Bone marrow edema · Mucus plugging · Fibroadenoma