Pulmonary Nodule
Information about the causes, symptoms, and treatment of localized lung growths.
Symptoms and causes
A pulmonary nodule is an abnormal accumulation of cells that forms in the lung. By definition, it is usually a small, round or oval lesion (no larger than 3 centimeters) and, in most cases, arises from scar tissue in the lung lining due to a previous infection.
Most pulmonary nodules are discovered incidentally or during a screening program and are benign, non-tumorous lesions. However, some nodules may be malignant.
Depending on their radiological characteristics, there are two types of pulmonary nodules:
Solid nodules: dense, uniform masses.
Subsolid nodules: less dense, slightly translucent nodules, which can be:
- Non-solid nodules: known as ground-glass nodules, appear as a hazy area through which the lung’s blood vessels are visible. In most cases, they are transient and disappear once the underlying condition resolves.
- Part-solid nodules: composed of a solid portion and a ground-glass component.
The prognosis of pulmonary nodules varies according to their nature:
- Benign pulmonary nodules: the most frequent type. Prognosis is excellent as they do not pose a health risk.
- Malignant pulmonary nodules: composed of cancerous cells, they can threaten the patient’s life. Prognosis depends on the stage at diagnosis, though early detection often allows treatment with high chances of cure.
Early detection of pulmonary nodules is essential, particularly if malignant. At-risk patients are advised to attend regular consultations for lung cancer screening.
Symptoms
Most pulmonary nodules are asymptomatic. Occasionally, benign nodules may cause:
- Cough
- Fever
- Fatigue
- Chest pain
Malignant nodules may present with:
- Persistent cough
- Coughing up blood
- Chest pain worsening with deep inhalation
- Wheezing
- Shortness of breath
- Fatigue
- Difficulty breathing
- Weight loss
Causes
Causes of pulmonary nodules differ according to their nature:
Benign nodules: usually due to a prior condition:
- Infections from fungi, viruses, or bacteria causing scar tissue in the lung lining, such as pneumonia, tuberculosis, cryptococcosis, aspergillosis, septic embolism, or COVID-19
- Granulomas: accumulation of immune cells in response to infection or inflammation
- Hamartomas: abnormal growth of fat, cartilage, or connective tissue
- Pulmonary inflammation
- Enlarged lymph nodes
- Vascular malformations
Malignant nodules: may be premalignant lesions, early-stage tumors, or metastases from other cancers reaching the lungs. Causes relate to general cancer risk factors.
Risk Factors
Factors increasing the risk of malignant pulmonary nodules include:
- Smoking
- Family or personal history of cancer
- Excessive exposure to radon, asbestos, or polluted environments
- Age: incidence rises after 55 years
The likelihood of benign nodules is higher in individuals with a history of infectious or inflammatory lung disease.
Complications
Benign pulmonary nodules rarely cause complications. When they do, they may include:
- Pneumothorax: accumulation of air between the lung and chest wall
- Bronchopleural fistula: abnormal connection between a bronchus and the pleural cavity
- Respiratory failure: inadequate oxygen supply to the blood or inability to remove carbon dioxide
Malignant pulmonary nodules can metastasize to other organs, commonly spreading to the brain, liver, bones, thoracic lymph nodes, or adrenal glands.
Prevention
Prevention measures for pulmonary nodules include:
- Avoid smoking
- Reduce exposure to pollutants
- Receive proper treatment for lung diseases
- Participate in lung cancer screening programs, typically for individuals over 55 with a smoking history of more than 30 pack-years
Which Specialist Treats Pulmonary Nodules?
Pulmonary nodules are diagnosed and treated by specialists in Pulmonology.
Pulmonary nodules are often detected incidentally. Their characteristics and number are determined using:
- Chest X-ray: can detect nodules larger than 9 millimeters. Fatty or calcified cysts may be visible, but the test is generally inconclusive for determining nature.
- Computed Tomography (CT) Scan of the Lungs: X-rays taken from multiple angles for a detailed 3D view, recommended for nodules larger than 10 millimeters or small lesions not visible on X-ray.
- Positron Emission Tomography (PET): uses a small radioactive substance to observe cellular activity, which is higher in cancer cells.
- Bronchoscopy: a flexible tube with a camera is inserted into the bronchi to examine the lungs and potentially take nodule samples.
- Lung Biopsy: tissue samples are analyzed to detect malignant cells.
Radiological evaluation allows specialists to determine nodule nature:
- Benign nodule: small, with smooth, well-defined edges, may appear anywhere in the lung
- Malignant nodule: larger size increases cancer likelihood. Lobulated edges indicate moderate malignancy risk; spiculated edges indicate high risk. Cancerous tumors are most frequently in the right lung, particularly the upper lobes.
Treatment
Treatment depends on the case. For nodules without malignancy suspicion, periodic monitoring is recommended. If stable over years, no intervention is required.
For cancerous nodules, treatment often combines surgery with additional procedures to remove all tumor cells:
- Surgery: removal via thoracotomy (open surgery) or thoracoscopy (minimally invasive endoscopic procedure)
- Radiotherapy: high-energy X-rays to reduce nodule size or destroy residual cancer cells
- Chemotherapy: specific drugs to fight cancer, often used when surgery is not advisable
