From the Guidelines
A pneumatocele size of 2 cm laterally or apically on chest X-ray (CXR) or any size on CT scan that can be safely accessed with radiological support is generally considered sufficient to intervene and prevent pneumothorax. The British Thoracic Society guideline for pleural disease, published in 2023 1, provides guidance on the management of pneumothorax, including the size threshold for intervention. According to this guideline, the decision to intervene depends on the clinical context, but a pneumatocele size of 2 cm or more on CXR or any size on CT scan that can be safely accessed is considered sufficient to intervene. Key factors to consider when evaluating the risk of pneumothorax due to a pneumatocele include:
- Size of the pneumatocele: larger pneumatoceles are at higher risk of rupture
- Location of the pneumatocele: subpleural pneumatoceles are at higher risk of rupture
- Tension within the pneumatocele: rapidly expanding pneumatoceles are at higher risk of rupture
- Underlying lung disease: patients with underlying lung disease are at higher risk of complications from pneumothorax. The guideline recommends regular review and monitoring of patients with pneumatoceles, and intervention such as percutaneous drainage or surgical resection may be necessary to prevent pneumothorax in patients with large or expanding pneumatoceles 1.
From the Research
Size Threshold for Pneumatocele to Cause Pneumothorax
- The size threshold for a pneumatocele to cause a pneumothorax is not strictly defined, but studies suggest that larger pneumatoceles are more likely to rupture and cause pneumothorax 2.
- A study found that lesions measuring 5 cm had a high risk of rupture (OR 6.8, CI 95% 1.1-42), and those measuring 3 cm were prone to this complication 2.
- For each centimeter that the pneumo-hematocele diameter increases, the OR for rupture increases 1.5 2.
- Another study reported a case of a large pneumatocele (10.2 × 6.2 cm2) that caused a pneumothorax, but the size threshold for rupture was not specified 3.
- A study on traumatic pneumatoceles in children found that the largest pneumatocele was 3.7 cm in diameter, but it did not report any cases of pneumothorax caused by pneumatocele rupture 4.
- A study on CT-guided lung biopsy found that small lesion size (< 2 cm) was a significant risk factor for pneumothorax, but it did not specifically address the size threshold for pneumatocele rupture 5.
- Overall, while there is no strict size threshold for pneumatocele rupture, larger pneumatoceles appear to be more likely to cause pneumothorax, with sizes above 3-5 cm being particularly concerning 2, 3.