Acute Cough Differential Diagnosis

The differential diagnosis for an acute cough can be extensive, encompassing a wide range of conditions from benign and self-limiting to serious and life-threatening. Here's a categorized approach to the differential diagnosis:

• Single Most Likely Diagnosis

  • Viral Upper Respiratory Tract Infection (URTI): This is the most common cause of an acute cough, often resulting from infections such as the common cold or flu. The justification for this being the single most likely diagnosis lies in its high prevalence and the fact that most acute coughs are self-limiting and resolve without specific treatment.

• Other Likely Diagnoses

  • Acute Bronchitis: Often follows a viral upper respiratory infection, characterized by inflammation of the bronchial tubes. It's a common cause of cough in both smokers and non-smokers.
  • Pneumonia: Can be caused by bacteria, viruses, or fungi, and presents with cough, fever, and possibly difficulty breathing. It's a significant concern, especially in vulnerable populations like the elderly, young children, and those with compromised immune systems.
  • Allergic Rhinitis: Seasonal or perennial allergies can cause chronic or acute cough due to postnasal drip.
  • Asthma: Characterized by episodic airway constriction, often triggered by allergens, exercise, or respiratory infections, leading to cough, wheezing, and shortness of breath.

• Do Not Miss Diagnoses

  • Pulmonary Embolism: Although less common, it's a life-threatening condition that can present with sudden onset of cough, often accompanied by chest pain and shortness of breath. The risk factors include recent surgery, immobilization, cancer, and genetic predispositions.
  • Cardiac Failure: Can cause cough due to pulmonary congestion, especially if the cough is worse when lying down (orthopnea) or wakes the patient from sleep (paroxysmal nocturnal dyspnea).
  • Tuberculosis (TB): A chronic bacterial infection that can cause cough, often accompanied by weight loss, night sweats, and hemoptysis. It's crucial to consider TB in individuals with risk factors such as immunocompromised states or recent travel to endemic areas.
  • Lung Cancer: Presents with cough, weight loss, and possibly hemoptysis. It's essential to consider in long-term smokers or those exposed to carcinogens.

• Rare Diagnoses

  • Cystic Fibrosis: A genetic disorder leading to chronic respiratory infections and cough, typically diagnosed in childhood but can be missed until adulthood.
  • Sarcoidosis: An autoimmune disease that can affect the lungs, causing cough and shortness of breath, among other symptoms.
  • Eosinophilic Pneumonia: A rare condition characterized by an accumulation of eosinophils in the lungs, often presenting with cough, fever, and respiratory distress.
  • Foreign Body Aspiration: More common in children, but can occur in adults, especially those with altered mental status or dysphagia, leading to sudden onset of cough and respiratory distress.

Each of these diagnoses has distinct clinical features and risk factors that guide the diagnostic approach. A thorough history, physical examination, and judicious use of diagnostic tests are essential for accurately diagnosing the cause of an acute cough.