Differential Diagnosis for Persistent Cough

The patient presents with a persistent cough for 7 weeks, accompanied by chest pain, severe coughing fits, intermittent wheezing, and exposure to secondhand smoke. The differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Asthma: The presence of persistent cough, wheezing, and chest pain, especially with coughing, along with the use of a Symbicort puffer (a common asthma medication), suggests asthma as the most likely diagnosis. The symptoms of asthma can be exacerbated by exposure to secondhand smoke.

• Other Likely Diagnoses

  • Chronic Obstructive Pulmonary Disease (COPD): Although the patient is a non-smoker, exposure to secondhand smoke could contribute to COPD. However, the absence of a significant smoking history and the patient's age make this less likely than asthma.
  • Allergic Rhinitis: Postnasal drip from allergic rhinitis can cause a persistent cough, and the patient's symptoms could be partly attributed to this, especially if there are other allergy symptoms present.
  • Gastroesophageal Reflux Disease (GERD): GERD can cause a chronic cough, especially if the patient experiences reflux at night, leading to morning coughing fits.

• Do Not Miss Diagnoses

  • Lung Cancer: Although less likely in a non-smoker, exposure to secondhand smoke increases the risk. A persistent cough that does not improve with treatment for other causes should prompt further investigation, including imaging studies.
  • Tuberculosis (TB): Given the duration of the cough and the potential for exposure to infectious diseases, TB should be considered, especially if the patient has been in contact with someone known to have TB or has recently traveled to areas with high TB prevalence.
  • Pulmonary Embolism: While less common, a pulmonary embolism can present with a sudden onset of cough and chest pain, and it is crucial to rule out this life-threatening condition, especially in patients with risk factors for thromboembolic disease.

• Rare Diagnoses

  • Cystic Fibrosis: Typically diagnosed in childhood, but mild forms can present later in life. The patient's symptoms and lack of previous lung function testing might warrant consideration of this diagnosis, although it is less likely.
  • Bronchiectasis: A condition characterized by damaged, widened airways, which can lead to a chronic cough and recurrent infections. It might be considered if other diagnoses are ruled out and the patient continues to have symptoms.
  • Sarcoidosis: An autoimmune disease that can affect the lungs, causing cough, wheezing, and chest pain. It is less common and would typically be considered after ruling out more likely causes.