Lung air-fluid level in a smoker

A 49-year-old man was referred for evaluation of an abnormal chest radiograph. A 25-pack-year smoker, he had a history of chronic shortness of breath on exertion with occasional coughing and whitish sputum production. He also had a history of hypertension. He had not had hemoptysis, fever, chills, weight loss, or other symptoms, and he had not traveled recently.

On examination, he appeared comfortable. His breath sounds were decreased bilaterally; the rest of his physical examination was normal. His medical history, social history, and review of systems were otherwise unremarkable.

His white blood cell count was 9.4 × 10⁹/L (reference range 4.5–11.0), with a normal differential. His hemoglobin concentration was 166 g/L (140–175).

Pulmonary function testing demonstrated moderate obstruction, with the following values:

• Forced expiratory volume in the first second of expiration/ forced vital capacity 0.65
• Forced expiratory volume in the first second of expiration 2.40 L (72% of predicted)
• Total lung capacity 7.11 L (92% of predicted)
• Diffusing capacity of lung for carbon monoxide 58% of predicted.

He underwent radiography (Figure 1) and computed tomography of the chest (Figure 2).

DIAGNOSIS: INFECTED EMPHYSEMATOUS BULLAE

The patient had infected emphysematous bullae.

The diagnosis can typically be made by the new development of an air-fluid level in a patient known to have preexisting emphysematous bullae.¹ If previous images are not available, the presence of other bullae in a patient with established chronic obstructive pulmonary disease, a thin-walled cavity, and a disproportionate presentation with impressive radiographic findings along with a subtle clinical picture can support the diagnosis.² In most reported cases, patients are not significantly symptomatic or ill.³ The differential diagnosis includes loculated parapneumonic pleural effusion,⁴ lung abscess,⁵ tuberculosis,⁶ and infected pneumatocele.

Since percutaneous aspiration of the bullae has been discouraged,² the causative organism is often not identified. Also, the role of bronchoscopy in the diagnostic evaluation and treatment of infected emphysematous bullae appears to be limited.⁷

Our patient had minimal symptoms and did not appear ill; he had a relatively unremarkable physical examination, no leukocytosis, and negative blood and sputum cultures, suggesting a benign presentation. In addition, chest radiography a few months before this presentation showed multiple large emphysematous bullae (Figure 3). The current chest radiograph suggested multiple thin-walled cavitary lesions with an air-fluid level, which was confirmed on computed tomography.

TREATMENT OF INFECTED EMPHYSEMATOUS BULLAE

Currently, there is no established therapy for infected emphysematous bullae. Because the presentation is usually relatively benign in most case series, conservative treatment with a prolonged course of antibiotics alone seems to be the most appropriate initial course of action. A follow-up evaluation with chest imaging is recommended. On the other hand, in patients with worse symptoms, percutaneous aspiration of the bullae should be considered, as it may guide antibiotic therapy.⁸

We started our patient on clindamycin and scheduled him for follow-up chest imaging in 6 weeks.