Pulmonary nodules: causes and diagnosis

Written by: Top Doctors®
Edited by: Top Doctors®

A pulmonary nodule, otherwise known as a lung nodule, is a rounded or elliptical growth on the lung. If seen in two dimensions, it looks circular whereas in three dimensions it takes an elliptical form. It is usually detected with a chest x-ray or scan. Modern scanners can detect pulmonary nodules of very small dimensions of between three millimetres and 20 millimetres for example, which previously would have gone undetected by a chest x-ray.

The detection of a lung nodule always generates concern in the patient as generally is interpreted as being synonymous with a non-benign disease. Fortunately most of the time lung nodules are detected by chance and not because of any abnormal symptoms, the cause is benign or harmless but it is also true that a lung nodule may go undetected by both patient and doctor.


What are the causes of lung nodules?

The list of causes of a pulmonary nodule is very long, perhaps numbering even more than 100, what interests the doctor and especially the patient is whether it is a benign or non-benign lesion.

Causes of benign lesions include infections, which could be current ones or old ones. In some cases there is lack of diagnosis. And if they are tumours, when it comes to tumours in the lungs, although there are benign tumours, such as amecomas or calcinoid tumours, they must be thought of as if they were not benign tumours.


How can lung nodules be diagnosed?

Usually the radiological characteristics of the lung nodule can guide diagnosis: if it is fatty, it could be a hamartoma if there is calcification, it might be an old lesion, but many times a diagnosis cannot be made at the first attempt.

Then the decision needs to be made as to whether to put the patient through more complicated, more invasive tests, or wait. If the dimensions are small, it is possible that the only thing to do is wait for, 3, 6, or 12 months to see if the growth develops as a benign or non-benign lesion. If the lesion is already at a size of around 10 millimetres more immediate tests are usual, which can be either Tac-Pet, bronchoscopy, or direct puncture. If there is suspicion that it is a non-benign lesion, then it is preferable to perform surgery to obtain firm diagnosis.  


What are the risk factors for lung nodules to be cancer?

The risk factors of lung nodules are very well defined. The main pulmonary nodule cause is tobacco and the factors of how much and for how long the patient smokes or did smoke. Other risk factors include emphysema, which is also detected by TAC, and bronchial obstruction.  For a patient between 55 and 60 years old who is a current smoker, and has emphysema and/or a bronchial obstruction, the probability that they will develop a cancer during the next 10 years is 10%. 


By Topdoctors
Pulmonology & respiratory medicine

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