What is the diagnosis for a 2-month-old baby with cough, runny nose, flaring of the ala nasi, increased work of breathing, and expiratory wheeze in all lower lung zones, but no fever?

Diagnosis: Bronchiolitis

The diagnosis is B. Bronchiolitis – this 2-month-old infant presents with the classic constellation of viral upper respiratory prodrome (cough, runny nose) followed by lower respiratory tract involvement (expiratory wheeze, increased work of breathing with nasal flaring), which defines bronchiolitis in infants under 2 years of age. 1

Clinical Reasoning

Why Bronchiolitis is the Correct Diagnosis

The American Academy of Pediatrics defines bronchiolitis as a viral lower respiratory tract infection characterized by acute inflammation, edema and necrosis of epithelial cells lining small airways, increased mucus production, and bronchospasm. 1, 2 This patient demonstrates the pathognomonic clinical presentation:

• Age: At 2 months old, this infant falls within the peak age group for bronchiolitis (most common in children <2 years, with highest risk <12 weeks). 1, 3
• Viral prodrome: Rhinorrhea (running nose) and cough represent the typical upper respiratory symptoms that precede lower tract involvement. 1, 3
• Lower respiratory signs: Expiratory wheeze in lower lung zones, nasal flaring, and increased work of breathing are the hallmark manifestations of bronchiolar obstruction. 1, 2
• Absence of fever: While fever can occur, its absence does not exclude bronchiolitis. 1

Why Other Options Are Incorrect

A. Pneumonia is excluded because:

• Pneumonia typically presents with focal findings on examination rather than diffuse bilateral wheezing. 4
• The clinical picture of viral upper respiratory prodrome followed by wheezing is characteristic of bronchiolitis, not pneumonia. 1

C. Bronchial asthma is excluded because:

• Asthma is extremely rare as a first presentation at 2 months of age. 1
• The American Academy of Pediatrics specifically states that children with recurrent wheezing episodes after the first year of life likely have asthma, but a first episode in an infant <2 years with viral prodrome is bronchiolitis. 5
• This is the first episode with clear viral trigger, not recurrent wheezing. 1

D. Viral croup is excluded because:

• Croup presents with inspiratory stridor, barky cough, and upper airway obstruction, not expiratory wheezing and lower airway disease. 1
• The physical findings of lower lung zone wheezing indicate small airway disease (bronchiolitis), not laryngotracheal inflammation (croup). 1

Important Clinical Considerations

Risk Assessment

This 2-month-old infant has a significant risk factor for severe disease due to age <12 weeks, which should prompt careful monitoring for progression. 1, 5 Additional risk factors to assess include:

• History of prematurity 1, 5
• Underlying cardiopulmonary disease 1, 5
• Immunodeficiency 1, 5

Diagnostic Approach

The diagnosis should be made clinically based on history and physical examination alone – routine chest x-rays and laboratory studies are not recommended and should not be obtained. 1

Management Pitfall

Despite the wheezing, bronchodilators (salbutamol/albuterol), corticosteroids, and antibiotics are not recommended for bronchiolitis, as they do not improve outcomes. 6, 7, 8, 4 Treatment is supportive only: nasal suctioning, oxygen if saturations <90%, and ensuring adequate hydration. 1, 5, 4