When a lung nodule or mass is detected on imaging, further investigation with a tissue biopsy may be necessary to determine its nature. This is especially important when the lesion is growing, large, or showing signs of malignancy, particularly in individuals at high risk for lung cancer. Tissue biopsy plays a crucial role in providing accurate diagnosis and determining the treatment plan.
The type of cells found in the biopsy—whether they are inflammatory, tuberculosis-related, or cancerous—directly affects the course of treatment and prognosis. Therefore, a biopsy is an essential first step in the diagnostic process. Let’s explore the various methods of obtaining lung tissue for examination.
Types of Lung Tissue Biopsy Methods
Lung tissue samples can be collected using three primary biopsy techniques:
1. CT-Guided Percutaneous Lung Biopsy (Transthoracic Needle Biopsy)
In this method, the biopsy needle is inserted through the skin to access the lung mass, typically when the lesion is located in the periphery of the lung. The procedure is guided by CT imaging, ensuring accurate needle placement.
Procedure:
- Fasting for at least 6 hours before the procedure
- Tissue is extracted using a thin needle, with 2-3 attempts made to increase diagnostic accuracy
- Post-procedure resting and chest X-ray to check for pneumothorax
Complications:
- Pneumothorax in 25-30% of cases, generally treated with oxygen therapy; in 5%, a chest tube may be required
- Other risks include lung bleeding and air embolism
Diagnostic Accuracy:
- This method has a diagnostic rate of 80-95%, with some cases requiring multiple attempts to secure a conclusive result.
2. Bronchoscopy with Ultrasound (EBUS-TBNA)
For masses located near the central airway, bronchoscopy allows for direct access to the lung tissue. An ultrasound bronchoscope may also be used to target lymph nodes or lesions within the mediastinum.
Procedure:
- Fasting for 6 hours before the procedure
- The bronchoscope is inserted through the nose or mouth into the bronchial tubes
- The procedure lasts approximately 15 minutes, with the possibility of extension if therapeutic interventions are needed
Diagnostic Accuracy:
- This method offers a sensitivity of 82-94% for lung cancer diagnosis and 89% for assessing mediastinal lymph node metastasis.
Complications:
- Rare complications may include pneumothorax, mediastinal bleeding, and airway polyps.
3. Video-Assisted Thoracoscopic Surgery (VATS) Biopsy
If less invasive methods fail to provide sufficient results or if there is a strong suspicion of malignancy, VATS may be performed to surgically remove part of the lung for biopsy.
Procedure:
- General anesthesia is required
- The procedure typically lasts 30 minutes to 1 hour, and the surgeon uses a thoracoscope to remove tissue
- A chest tube is inserted post-surgery to monitor for air leaks or bleeding
Complications:
- Risks include bleeding, pneumothorax in the opposite lung, arrhythmias, and myocardial ischemia.
Choosing the Right Biopsy Method for Lung Tissue
The biopsy method selected depends on several factors, including the location and size of the lung lesion, as well as the patient’s overall health. Often, multiple biopsy methods may be used to obtain an accurate diagnosis.
For example, a patient might undergo CT-guided biopsy, followed by bronchoscopy, and then surgery if the lesion is still undetermined. This multi-step approach helps ensure a thorough evaluation, especially when malignancy is strongly suspected.
Conclusion
Lung tissue biopsy is essential in the diagnosis of lung diseases, including lung cancer. The method chosen depends on the lesion’s size, location, and the patient’s condition. Since no method is foolproof, multiple biopsies may be necessary, and results typically take 7-10 days to process. Additional tests, such as genetic analysis, may extend the diagnostic timeline, but ultimately, these biopsies are key in determining the correct treatment path.