**Question:** A 6 yr old girl with non productive cough, mild stridor for 3 months duration following a lower respiratory tract infection. Patient is improving but suddenly developed wheeze, productive cough, mild fever and hyperlucency on CXR and PFT shows obstructive curve. Diagnosis is:

A. Bronchiolitis
B. Bronchitis
C. Pneumonia
D. Asthma

**Core Concept:**

The presented case describes a pediatric patient with a history of lower respiratory tract infection, followed by the development of wheeze, productive cough, and fever. The chest X-ray shows hyperlucency (increased lung opacity), which is indicative of increased air flow and decreased lung compliance. PFT (Pulmonary Function Tests) reveal an obstructive curve, further supporting the diagnosis of obstructive lung disease.

**Why the Correct Answer is Right:**

The correct answer is D. Asthma, because asthma is a chronic respiratory condition characterized by episodic and reversible airway obstruction. In this case, the patient presents with a history of lower respiratory tract infection, followed by the development of wheeze, productive cough, and fever. These symptoms are consistent with an acute exacerbation of asthma, which is triggered by viral infections in this case. The patient's lungs show increased airflow (hyperlucency) on CXR and an obstructive curve on PFT, indicating reversible airway obstruction.

**Why Each Wrong Option is Incorrect:**

A. Bronchiolitis: Bronchiolitis is a respiratory illness affecting infants and young children, typically caused by viral infections. While wheeze and respiratory distress are common features of bronchiolitis, the patient's history of lower respiratory tract infection followed by an acute exacerbation of asthma is more consistent with asthma.

B. Bronchitis: Bronchitis is an inflammation of the bronchi, usually due to viral infection. Although wheeze and productive cough may be seen in bronchitis, the patient's history of lower respiratory tract infection followed by an acute exacerbation of asthma is more consistent with asthma.

C. Pneumonia: Pneumonia is an infection affecting the lungs, caused by bacteria, viruses, or other microorganisms. While wheeze and respiratory distress are common features of pneumonia, asthma is a more likely diagnosis based on the patient's history and clinical presentation.

**Clinical Pearls:**

1. In acute asthma exacerbation, the patient usually presents with a history of viral respiratory tract infection followed by wheezing, productive cough, and fever.
2. Asthma exacerbations can be triggered by viral infections, leading to reversible airway obstruction due to inflammation and bronchoconstriction.
3. The clinical features of wheeze, productive cough, and fever are common in lower respiratory tract infections like pneumonia, bronchitis, and bronchiolitis. However, the history of a viral respiratory tract infection followed by an acute exacerbation of asthma is more consistent with asthma than these conditions.

**Correct Answer Explanation:**

The correct answer is D. Asthma due to the following reasons:

1. The patient's history of lower respiratory tract infection followed by an acute exacerbation