pulmonary nodule

A pulmonary nodule is a small, roundish spot of denser tissue inside the lung — typically up to about three centimetres across — surrounded by normal air-filled lung. Think of a single small marble seen against a sponge. They are extremely common, often turning up by chance when the chest is imaged for some other reason, and the great majority are harmless.

The key clinical task is sorting the harmless from the worrying. Many nodules are old healed infections, scars, small benign growths or clusters of inflammation. A minority, however, are early lung cancers, and a nodule may be the first and only sign of a tumour small enough to cure. Because most nodules are too small to safely biopsy at first, the response is usually careful assessment rather than immediate action.

Doctors weigh features that shift the odds: larger size, irregular or spiky edges, growth over time, and a person's age and smoking history all raise concern, whereas tiny, smooth, fat- or calcium-containing nodules are reassuring. Depending on this risk, the plan may be interval CT scans to watch for growth, a PET-CT to assess metabolic activity, or a biopsy. A nodule that stays unchanged over a couple of years is very likely benign.