Differential Diagnosis for Recurrent Lung Cavitary Lesions and Empyema
Single Most Likely Diagnosis
- Anthrax: Although less common, the history of methamphetamine use could potentially increase the risk of exposure to contaminated substances. The negative cultures and AFB studies do not rule out anthrax, as it can be difficult to culture. The slightly elevated adenosine deaminase (ADA) from pleural fluid is nonspecific but can be seen in various infections, including those caused by bacteria.
Other Likely Diagnoses
- Nocardia infection: This is a common cause of lung abscesses and empyema, especially in immunocompromised patients. The negative cultures do not rule out Nocardia, as it can be difficult to grow.
- Actinomycosis: This bacterial infection can cause lung abscesses and empyema, and the negative cultures and AFB studies do not rule it out.
- Methamphetamine-induced lung injury: Methamphetamine use has been associated with various lung injuries, including pneumothorax, pneumomediastinum, and lung abscesses.
Do Not Miss Diagnoses
- Tuberculosis (TB): Although the AFB studies were negative, TB can be difficult to diagnose, and a high index of suspicion is necessary, especially in patients with risk factors for TB exposure.
- Fungal infections (e.g., Blastomyces, Cryptococcus): Although the initial fungal studies were negative, it is essential to consider other fungal infections that may not have been tested for.
- Pulmonary embolism with infarction: This can cause cavitary lesions and empyema, especially in patients with a history of substance use, which increases the risk of thromboembolic events.
Rare Diagnoses
- Parasitic infections (e.g., Paragonimus, Echinococcus): These infections can cause lung cysts and empyema, although they are rare in most parts of the world.
- Rheumatoid arthritis-associated lung disease: This can cause lung nodules and cavitation, although it is less common than other manifestations of rheumatoid arthritis.
- Wegener's granulomatosis (Granulomatosis with Polyangiitis): This autoimmune disease can cause lung cavitation and empyema, although it is rare and typically associated with other systemic symptoms.