A 4-year-old child has episodic wheezing and a non-productive cough for four weeks, worse at night, with a history of atopy. Which is the most likely diagnosis?

• A. Bronchiolitis
• B. Croup
• C. Asthma
• D. Cystic fibrosis

Answer: (C)

Episodic wheezing with a dry cough that worsens at night in a child with a history of atopy points to asthma because allergic inflammation causes reversible airway obstruction and hyperresponsiveness, producing intermittent wheeze and nocturnal symptoms. The nighttime cough reflects the circadian pattern of airway inflammation, and atopy is a major risk factor, making asthma the most likely diagnosis.

Bronchiolitis is more common in infants and typically presents with acute viral-induced distress, crackles, and tachypnea rather than a chronic pattern of nocturnal wheeze in an atopic child. Croup features a distinctive barking cough and inspiratory stridor with usually a younger age group and viral onset. Cystic fibrosis involves a chronic productive cough, poor weight gain, and recurrent infections, not primarily episodic wheeze with nocturnal symptoms.