What is the incidence of vape-related bronchiolitis obliterans, also known as popcorn lung?

Incidence of Vape-Related Popcorn Lung (Bronchiolitis Obliterans)

The exact incidence of vape-related bronchiolitis obliterans (popcorn lung) is not well established, with only rare documented cases reported in the medical literature despite widespread vaping use. 1, 2

Clinical Background and Pathophysiology

Bronchiolitis obliterans is a severe form of fixed airway disease characterized by:

• Irreversible fibrosis and narrowing of the bronchioles
• Progressive dyspnea and fixed airflow obstruction
• Potentially fatal respiratory compromise

The condition was first identified in microwave popcorn factory workers exposed to diacetyl (2,3-butanedione), earning it the nickname "popcorn lung" 3, 4. Diacetyl and similar flavoring compounds have been detected in many flavored e-cigarette liquids 3.

Documented Cases and Epidemiology

While EVALI (E-cigarette or Vaping Product Use-Associated Lung Injury) has been extensively documented with 2,409 hospitalized cases reported to the CDC by December 2019 5, confirmed cases of bronchiolitis obliterans specifically attributed to vaping are extremely rare:

• Only isolated case reports exist, such as the Canadian youth case documented in 2019 2
• This case required ECMO support and resulted in persistent, fixed airflow obstruction with gas trapping
• The clinical presentation was distinct from the typical alveolar injury pattern seen in most EVALI cases 2

Risk Factors and Mechanisms

The primary chemical compounds implicated in vape-related bronchiolitis obliterans include:

• Diacetyl (2,3-butanedione) - a butter-flavoring compound
• 2,3-pentanedione - a diacetyl substitute with similar toxicity
• Other α-dicarbonyl compounds including methylglyoxal 6

These compounds can cause:

• Direct airway epithelial necrosis
• Damage to biological molecules
• Disruption of protein homeostasis
• With chronic exposure, airway fibrosis resembling bronchiolitis obliterans 6

Diagnostic Considerations

Diagnosis of vape-related bronchiolitis obliterans requires:

1. History of e-cigarette or vaping product use
2. Exclusion of infectious etiologies
3. Chest imaging showing characteristic patterns (often centrilobular "tree-in-bud" nodularity)
4. Pulmonary function tests showing fixed airflow obstruction
5. In some cases, lung biopsy showing bronchiolitis obliterans 1, 2

Clinical Implications

Healthcare providers should be aware that:

• Bronchiolitis obliterans represents a distinct and severe form of vaping-related lung injury
• It differs from the more commonly reported EVALI pattern of alveolar injury
• The condition may be underdiagnosed due to its similarity to other obstructive lung diseases
• Long-term outcomes include persistent airflow limitation and reduced exercise tolerance 2

Prevention and Management

The CDC recommends:

1. Complete cessation of all e-cigarette and vaping product use
2. Hospitalization for patients with significant respiratory compromise
3. Consideration of corticosteroid therapy
4. Close monitoring for clinical deterioration
5. Follow-up within 48 hours of discharge for hospitalized patients 5, 1

While the exact incidence remains unknown, the presence of diacetyl and similar compounds in e-cigarette liquids, combined with documented cases of severe bronchiolitis, suggests that vaping poses a real risk for this serious lung condition.