Can a pulmonary nodule less than 4 millimeters be biopsied?

From the Guidelines

Biopsying a pulmonary nodule less than 4 millimeters is not recommended as a first approach due to technical challenges and low diagnostic yield. The preferred approach for these small nodules is radiological surveillance with serial CT scans, as outlined in guidelines such as those suggested for Asia 1. This approach involves follow-up imaging at intervals such as 12 months for nodules ≤ 4 mm in diameter with low clinical probability of malignancy.

Key Considerations

• The size of the nodule (≤ 4 mm) poses significant technical challenges for accurate targeting with needle biopsy techniques.
• The diagnostic yield of biopsying such small nodules is low, and the risk of complications may outweigh potential benefits.
• Radiological surveillance allows for the monitoring of nodule growth or the development of concerning features, which can then prompt reconsideration of biopsy or other interventions.
• Advanced biopsy techniques, such as CT-guided transthoracic needle biopsy, electromagnetic navigational bronchoscopy, or robotic bronchoscopy, may be considered in select cases but require specialized expertise and equipment.

Decision Making

The decision to biopsy a small pulmonary nodule should be individualized, taking into account the patient's overall clinical context, risk factors for malignancy, and after multidisciplinary discussion involving relevant specialists 1. This approach ensures that the management plan is tailored to the individual patient's needs and balances the risks and benefits of different strategies.

Surveillance Protocols

Following established protocols such as those suggested for Asia 1, or other relevant guidelines, is crucial for the effective management of small pulmonary nodules. These protocols provide a framework for determining the appropriate follow-up intervals based on nodule size and clinical probability of malignancy, helping to ensure that patients receive appropriate care while minimizing unnecessary interventions.

From the Research

Biopsy of Pulmonary Nodules Less Than 4 Millimeters

• The feasibility of biopsying pulmonary nodules less than 4 millimeters is a topic of discussion in the medical field, with various studies providing insights into the diagnostic accuracy and safety of such procedures 2, 3, 4, 5, 6.
• According to a study published in 2008, for nodules less than 4mm, a follow-up CT at 12 months is recommended in high-risk persons, whilst for low-risk persons no follow-up is needed 3.
• Another study from 1996 compared the diagnostic accuracy and safety of CT-guided percutaneous needle aspiration biopsy of pulmonary nodules less than or equal to 1.5 cm in diameter with those of nodules greater than 1.5 cm in diameter, and found that the diagnostic accuracy for small nodules was 74%, a statistically significant difference compared to large nodules 4.
• A 2017 study evaluated the incidence of malignancy in nodules 5 mm or less in patients with osteosarcoma and Ewing sarcoma, and found that size of pulmonary nodules <5 mm was not entirely predictive of benign status 5.
• A 2020 study assessed the diagnostic performance and risk factors associated with biopsy failure in nodules ≤1 cm, and found that biopsy specimens were adequate for diagnosis in 87% of cases, with a diagnostic yield for malignant and benign lesions of 93% and 65%, respectively 6.

Diagnostic Accuracy and Safety

• The diagnostic accuracy of biopsying pulmonary nodules less than 4 millimeters is generally lower compared to larger nodules, with a study finding a diagnostic accuracy of 74% for small nodules 4.
• The safety of biopsying small pulmonary nodules is a concern, with complications such as pneumothorax and chest tube placement reported in the literature 4, 6.
• However, the complication rates for biopsying small pulmonary nodules are generally low, with a study finding that the prevalence of pneumothorax was approximately 2% 4.

Management and Follow-up

• The management of pulmonary nodules less than 4 millimeters depends on various factors, including the patient's risk factors, nodule size, and imaging characteristics 2, 3.
• Follow-up CT scans are often recommended to assess for nodule growth, with the frequency of follow-up depending on the patient's risk factors and nodule characteristics 3.
• Biopsy may be considered for nodules that are growing or have suspicious characteristics, although the decision to biopsy should be made on a case-by-case basis, taking into account the patient's individual risk factors and preferences 2, 5, 6.