Pulmonary Nodule

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Pulmonary Nodule refers to a small, round or oval lesion in the lungs that measures less than 3 cm in diameter. It is often detected incidentally on imaging and can be benign or malignant.

Aetiology

Pulmonary nodules can result from various causes:

  • Benign Causes:
    • Infectious granulomas (e.g., tuberculosis, fungal infections).
    • Hamartomas.
    • Rheumatoid nodules or other inflammatory conditions.
  • Malignant Causes:
    • Primary lung cancer (e.g., adenocarcinoma, squamous cell carcinoma).
    • Metastatic cancer (e.g., breast, colorectal, renal cell carcinoma).

Pathophysiology

The development of pulmonary nodules depends on their underlying cause:

  • Benign Nodules: often result from inflammation or fibrotic changes in response to infection or autoimmune diseases.
  • Malignant Nodules: develop due to uncontrolled cellular growth, often originating from primary lung cancer or metastatic spread.

Risk Factors

  • History of smoking (significant risk for malignancy).
  • Age >50 years.
  • Previous or family history of cancer.
  • Exposure to occupational hazards (e.g., asbestos, radon).
  • Chronic lung conditions such as COPD or interstitial lung disease.

Signs and Symptoms

Most pulmonary nodules are asymptomatic and found incidentally. If symptomatic, they may present with:

  • Cough or chest pain (if adjacent to pleura).
  • Haemoptysis (especially in malignant nodules).
  • Unexplained weight loss or fatigue in malignancy.

Investigations

Key investigations include:

  • Chest X-ray: initial imaging to identify the nodule.
  • CT Thorax:
    • Benign Nodules: smooth, well-defined margins.
    • Malignant Nodules: spiculated or irregular margins, larger size (>8 mm), and presence of calcifications.
  • PET-CT Scan: to assess metabolic activity of the nodule (higher uptake suggests malignancy).
  • Biopsy:
    • CT-guided biopsy or bronchoscopy for histological diagnosis.
  • Sputum Cytology: useful in centrally located malignant nodules.
  • Blood Tests:
    • Full blood count (FBC) to identify anaemia or leukocytosis.
    • Consider tumour markers (if clinically indicated) such as Carcinoembryonic Antigen (CEA) (elevated in advanced-stage lung cancer, particularly adenocarcinoma), CA-125 (elevated in advanced-stage lung cancer, particularly adenocarcinoma), Alpha-Fetoprotein (AFP) (elevated in germ cell tumours with lung metastasis), and CA 19-9 (elevated in lung adenocarcinoma but more associated with gastrointestinal malignancies).

Management

1. Surveillance:

  • For low-risk nodules (<8 mm, no risk factors for malignancy): Repeat CT scan at 3, 6, or 12 months to monitor growth.

2. Biopsy or Resection:

  • For high-risk nodules (spiculated, >8 mm, or PET-positive): Consider biopsy or surgical removal.
  • Video-assisted thoracoscopic surgery (VATS) is commonly used for resection.

3. Malignant Nodules:

  • Refer for oncological treatment, including chemotherapy, radiotherapy, or immunotherapy based on tumour staging.

Referral

Refer to secondary care in the following scenarios:

  • Respiratory Specialist: for further assessment of suspicious nodules requiring CT or PET-CT imaging.
  • Oncology Team: for confirmed malignant nodules requiring staging and management.
  • Thoracic Surgeon: for consideration of surgical resection of nodules.
 
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