Differential Diagnosis for Chronic Cough in a Non-Smoker

Given the patient's presentation of chronic cough without GERD or heart failure and zero eosinophils, the following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Chronic Bronchitis: This is a common cause of chronic cough in non-smokers, often related to prolonged exposure to air pollutants or occupational exposures. The absence of eosinophils and the chronic nature of the cough support this diagnosis.
• Other Likely Diagnoses
  • Asthma: Although eosinophils are often elevated in asthma, a subset of patients with asthma can have normal or low eosinophil counts. Asthma should be considered, especially if there are symptoms of wheezing, shortness of breath, or cough variability.
  • Bronchiectasis: This condition involves permanent dilation of parts of the airways and can cause chronic cough due to recurrent infections and inflammation. It's less common but should be considered, especially if the patient has a history of recurrent respiratory infections.
  • Tuberculosis (TB): Although less common in some regions, TB can present with chronic cough and should be considered, especially if the patient has been exposed to TB, has traveled to or lived in areas with high TB prevalence, or has risk factors such as immunosuppression.
• Do Not Miss Diagnoses
  • Lung Cancer: Although less likely in a non-smoker, lung cancer can present with chronic cough and must be considered to avoid missing a potentially fatal diagnosis. Risk factors such as exposure to carcinogens (e.g., asbestos, radon) or a family history of lung cancer increase the likelihood.
  • Pulmonary Embolism: While typically presenting acutely, chronic or recurrent pulmonary emboli can cause chronic cough. This diagnosis is critical to consider due to its high mortality rate if untreated.
• Rare Diagnoses
  • Sarcoidosis: A systemic granulomatous disease that can affect the lungs and cause chronic cough. It's less common and often presents with other systemic symptoms, but it should be considered in the differential diagnosis of chronic cough.
  • Histiocytosis X (Langerhans Cell Histiocytosis): A rare disorder that can cause pulmonary symptoms, including chronic cough, due to the accumulation of Langerhans cells in the lungs.
  • Cystic Fibrosis: Typically diagnosed in childhood, but mild forms can present in adulthood with chronic cough among other symptoms. It's rare but should be considered, especially if there's a family history or other suggestive symptoms like recurrent sinusitis or malabsorption.