Differential Diagnosis for Wheezing in a Smoker Taking Montelukast

• Single Most Likely Diagnosis
  • Asthma: The patient is already taking montelukast, a leukotriene receptor antagonist commonly used in the treatment of asthma, suggesting that asthma is a pre-existing condition. Smoking can exacerbate asthma symptoms, including wheezing.
• Other Likely Diagnoses
  • Chronic Obstructive Pulmonary Disease (COPD): Smoking is a major risk factor for COPD, which can cause wheezing among other symptoms like cough and shortness of breath. The fact that the patient is already experiencing wheezing suggests that COPD could be a contributing factor.
  • Bronchitis: Acute or chronic bronchitis, often associated with smoking, can cause wheezing. The inflammation of the bronchial tubes can lead to symptoms similar to those of asthma.
• Do Not Miss Diagnoses
  • Pneumonia: Although less likely, pneumonia can cause wheezing, especially in smokers who are more susceptible to respiratory infections. Missing this diagnosis could lead to severe consequences, including sepsis and death if not promptly treated.
  • Pulmonary Embolism: While not directly related to wheezing, pulmonary embolism can cause sudden onset of shortness of breath and could be considered in the differential diagnosis of a smoker with respiratory symptoms, given the increased risk of thromboembolic events in smokers.
• Rare Diagnoses
  • Alpha-1 Antitrypsin Deficiency: A genetic disorder that can cause COPD-like symptoms in smokers and non-smokers alike. It's less common but should be considered in smokers with a family history of the condition or with symptoms that are not typical of more common diseases.
  • Churg-Strauss Syndrome: A rare autoimmune condition that can cause asthma-like symptoms, including wheezing, and is often associated with eosinophilia. It's a diagnosis that would be considered if the patient does not respond to standard asthma treatment and has other systemic symptoms.