What are Lung Nodules?

The lung nodules usually are asymptomatic and diagnosed incidentally during controls. There are two types of lung nodules, malign and benign

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What is a Lung Nodule?

Lung nodules; are lesions in the form of small white dots detected on chest X-ray and Computed Tomography during scanning.

Nodular lesions are less than 3 cm in the lung, surrounded by lung parenchyma, accompanied by enlarged lymph nodes, pneumonia, fluid accumulation, or abnormal tissue growth.

Lung Nodule Symptoms

Generally, they are asymptomatic and detected randomly during the examination. They rarely give symptoms if malignant or associated with infection and systemic disease.

  • Cough
  • Bloody sputum
  • Wheezing, expectoration
  • Fever due to pneumonia or an underlying disease is a common symptom.

In Computed Tomography, these nodules can be in solid, ground-glass opacity, or "mixed" structure with solid and ground-glass opacities. These nodules, which are not completely solid, are called "subsolid nodules."

There are three critical conclusions in the literature regarding lung nodules.

  1. Nodules are common structures in an average of 25% (8-51%) cases.
  2. Nodules are mostly multiple rather than single.
  3. Most nodules are smaller than 1 cm.

Causes of Lung Nodules

  1. Benign diseases mainly result in lung nodules.
    • Bacterial infections (such as pneumonia and abscess formation)
    • Tuberculosis (Granuloma)
    • Parasitic diseases (such as hydatid cysts)
    • Fungal infections
    • Sarcoidosis
    • Hamartoma
    • Rheumatoid arthritis
    • Some systemic diseases
  2. Lung cancer-malignant causes
    • Lung cancer
    • Metastasis
      • Metastasis from lung cancer
      • Metastasis of another cancer
    • Precancerous lesions

As seen above, the frequency of nodules in the lung is high, and these results show that not every nodule means cancer, and it is a common condition. Therefore, only some nodules require an operation.

In addition, not every nodule is cancerous; however, it is necessary to consult with a branch specialist. Nodules are common in the following organs too:

    • Thyroid
    • Lung
    • Liver
    • Breast.

We decide whether they are malignant or benign by performing some examinations (Thorax CT and PET -CT) or a biopsy/surgery.

Lung Nodule

Figure 1. PET-CT image of the nodule in the left lung. The nodule is in the upper lobe of the left lung. After the segmentectomy performed by robotic surgery, the result was benign.

Is Every Nodule Cancerous?

How Do We Decide If These Lung Nodules Are Malign or Benign?

When the patient is diagnosed with a lung nodule, a stressful process begins for the patient and the doctor.
If the lung's nodule is malignant, it can be completely removed with surgery in early diagnosis, and the patient's recovery will be quick.
Or, unnecessary surgical intervention is avoided in benign nodules. When the nodules are benign, they are followed up. If there is a wrong decision and the lesion is cancer, the tumor may spread and lose the chance for surgery and early recovery.

Therefore, with the development of technology, it is easy to detect nodules. However, deciding whether these nodules are cancer or benign is still challenging.
It is unnecessary to remove every nodule. Therefore, when a lung nodule is detected, we discuss the patient in the council center and make the most accurate decision. We prefer such a way in our center. We decide according to the conclusion of the council.

  • Chest diseases
  • Thoracic surgery
  • Radiology
  • Nuclear Medicine (PET-CT)
  • And other branches participate in our council.

In general, we refer patients with the following features for further investigations.

  • Having a family history of cancer
  • Elderly and middle-aged patients
  • Some habits
    • Smokers - smoking and advanced age are risks for cancer.
    • Ex-smokers
      • People over 40 with a history of cancer in their first-degree relatives are at high risk.
    • Malignant radiological features of the nodule
      • Size
      • Large nodule diameter:
        • If the nodule diameter is less than 3mm, the probability of cancer is 0.2%.
        • If the nodule diameter is 4 mm, the cancer risk is below 1%.
        • If the nodule diameter is between 8-20 mm, the cancer risk is 18%.
        • If the nodule diameter is more than 20 mm, the risk of cancer is 50-64%.
      • Borders of nodules
        • If the nodules' boundaries are unclear
        • The cancer risk of nodules with irregular walls is five times higher.
        • Malignant nodules usually show a lobulated or spicular margin structure. 60-90% of nodules with this type of wall are malignant.
      • Calcification
        • If there is calcification in the nodule, the risk of cancer is low.
      • Density properties
        • Nodules can be solid, of ground glass opacity, or "mixed" structure with solid and ground glass components; These nodules, which are not completely solid, are called "subsolid nodules."
        • The probability of malignancy in solid nodules is 7%
        • and 18% in pure subsolid nodules.
        • Malignancy risk is 63% in partial subsolid nodules.
        • The risk of malignancy depends on the size of the partially solid component.
      • Nodule growth during follow-up
        • Nodule growth during follow-up: If the patient has an old CT, it should be requested to compare the changes on time.
        • The risk of cancer is high if there is more than 25% growth compared to the old CT.
      • Therapy resistant nodule
      • Nodule in PET-CT

Characteristics of Benign Nodules in the Lung

  • Children and young age
  • Small nodule diameter
  • Calcification in the nodule
  • Regression of the nodule with antibiotics or other treatment
  • Having clear boundaries
  • No progression in the follow-up
  • Clear rounded borders of the nodule

In the Nodule Council, we discuss the abovementioned nodule characteristics.

We say there is no need to follow up if:

  • There is no growth in a lung nodule in a 2-year follow-up; in some cases, such as ground glass opacity, after a 3-year follow-up, no further investigation is required.

In general, a follow-up is continued for longer intervals.

  • Nodule size (mm) classifies Low-risk patients and High-risk patient
  • Nodule ≤ 4 mm No need for follow-up in low-risk patients, CT follow-up in 12 months, and no follow-up if there is no change in high-risk patients
  • Nodule 4-6 mm CT follow-up at 12 months; if there is no change, no follow-up Initially at 6 to 12 months, then 18 to 24 months if the size does not change
  • Nodule 6-8 mm Initially followed up in 6 to 12 months, then follow-up at 18 to 24 months if the size does not alter initially 3 to 6 months, then 9 to 12 months if the size does not change

How to Diagnose Lung Nodules?

Sometimes we perform diagnostic biopsies such as:

  • Tru-cut biopsy
  • bronchoscopy
  • If it is centrally located- VATS wedge resection

If cancer is suspected, we recommend surgical removal.
Removal is recommended in the lung nodules of the high-risk patient group; we prefer radiological follow-up at specific intervals in the patient group without risk factors. If we detect that the size of the nodule has increased and there is a change in its characteristics, we recommend surgery immediately.
We perform the surgical removal (single port VATS) or enter through two incisions to remove the nodule (thoracoscopy, VATS). If it is not cancer, we terminate the procedure.

Note 1: The American pulmonology specialist group recommends PET-CT for these types of nodules with a low probability of malignancy in a diameter of 8-10 mm. Our country's insurance covers PET-CT in nodules of 1 cm and above. So, PET-CT for nodules of 1 cm and above.

Note 2: Patients over 40 with 1st-degree relatives with a history of cancer, ex-smokers, or current smokers are in the high-risk group. The risk of cancer increases with advanced age, and the number of cigarettes smoked.

Note 3: If the nodule is above 1 cm, the risk of cancer increases, so either RADIOLOGICAL (TTIAB or Tru-cut biopsy/SURGICAL biopsy (VATS) or close follow-up is required. At the slightest suspicion, surgical removal is life-saving. If it is malignant, it spreads quickly because there is a vast vascular network in the lung. We usually have the chance to operate on only 20% of the patients. The remaining patient group comes to us in the late stages and loses the possibility of surgery. Therefore, early diagnosis and surgery are critical.

Note 4: Non-solid or partially solid nodules should be followed for extended periods to exclude the possibility of slow-growing adenocarcinomas.

Prof. Dr. Adalet DEMİR

Pthoracic Surgery

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