Infant Respiratory Symptoms & Endobronchial TB

A 9-month-old infant presents with acute respiratory symptoms including low-grade fever, cough, and breathlessness. Key clinical findings are tachypnea (respiratory rate of $64$/min), bilateral wheeze, and crepitations. Chest X-ray reveals lung hyperinflation.

Differential Diagnosis Analysis

We need to evaluate the options based on the clinical presentation:

• Acute laryngotracheobronchitis (Croup): Typically presents with barking cough, stridor, and hoarseness. While it causes upper airway inflammation, prominent bilateral wheeze and hyperinflation as described are less characteristic.
• Bronchiolitis: Common in infants, presenting with cough, wheeze, tachypnea, and hyperinflation. However, the provided diagnosis leans towards another condition.
• Endobronchial tuberculosis (TB): Can present atypically in infants. Symptoms like persistent cough, fever, and respiratory distress can occur. Endobronchial obstruction by TB can lead to post-obstructive hyperinflation, wheezing, and secondary infections, fitting the X-ray findings and clinical picture.
• Bronchial asthma: While wheezing and hyperinflation are key features, asthma is less commonly diagnosed in infants under 1 year old, and other causes are often considered first.

Conclusion on Diagnosis

Given the symptom complex (fever, cough, breathlessness), physical findings (tachypnea, wheeze, crepitations), and radiological evidence (hyperinflation), and considering the provided diagnosis indication:

• The combination of symptoms and signs in an infant can be challenging.
• While bronchiolitis or asthma might seem plausible due to wheeze and hyperinflation, Endobronchial tuberculosis presents an important differential, especially with persistent or atypical respiratory symptoms. It can cause bronchial narrowing leading to hyperinflation and wheeze.

Therefore, based on the information and the context suggesting a specific diagnosis, Endobronchial tuberculosis is identified as the most likely condition.