What Is a Pulmonary Bulla?

Lung bullae are abnormal, air-filled spaces that develop within the lung parenchyma—typically measuring greater than 1 centimeter in diameter. Unlike normal alveoli, bullae lack functional pulmonary tissue and are surrounded by thin, avascular walls composed primarily of collapsed or fibrotic lung architecture. They most commonly arise in the context of underlying emphysema, particularly centrilobular emphysema associated with chronic smoking, but may also occur in alpha-1 antitrypsin deficiency, Marfan syndrome, Ehlers-Danlos syndrome, or following certain infections or inflammatory lung diseases.

Clinically, small bullae are often asymptomatic and discovered incidentally on chest imaging—such as radiography or computed tomography (CT). Larger bullae, however, can compress adjacent healthy lung tissue, impairing ventilation and gas exchange. This may lead to dyspnea, reduced exercise tolerance, or recurrent respiratory infections. A critical complication is spontaneous rupture, resulting in a pneumothorax—especially in tall, thin young adults—a presentation sometimes termed “primary spontaneous pneumothorax.” In severe cases, giant bullae may occupy more than one-third of a hemithorax, significantly compromising respiratory mechanics and oxygenation.

Diagnosis relies predominantly on high-resolution CT scanning, which precisely delineates size, number, location, and wall characteristics of bullae, while distinguishing them from cysts, cavities, or blebs. Management is individualized: asymptomatic bullae require no intervention beyond smoking cessation and surveillance. Symptomatic or complicated cases—particularly those causing significant volume loss, recurrent pneumothorax, or hypoxemia—may warrant surgical resection (e.g., bullectomy) or, in select patients with diffuse emphysema, lung volume reduction surgery (LVRS) or endobronchial valve placement.