A 71/2 year old girl with non productive cough, mild stridor for 3 months duration, patient is improving but suddenly developed wheeze, productive cough, mild fever and on x-ray hyperlucency and PFT shows obstructive curve. The most probable diagnosis is,
**Core Concept**
The patient's presentation of non-productive cough, mild stridor, and subsequent development of wheeze, productive cough, and hyperlucency on X-ray, along with obstructive curve on Pulmonary Function Tests (PFTs), suggests a condition characterized by recurrent airway obstruction and inflammation. This condition often affects children and is associated with a high risk of respiratory complications.
**Why the Correct Answer is Right**
The patient's symptoms and diagnostic findings are consistent with Cystic Fibrosis (CF), a genetic disorder caused by mutations in the CFTR gene, leading to abnormal chloride transport across epithelial surfaces. This results in thick and sticky mucus production, which obstructs the airways and leads to recurrent respiratory infections. The PFTs showing an obstructive curve indicate airway obstruction, which is a hallmark of CF. The presence of hyperlucency on X-ray suggests bronchiectasis, a common complication of CF.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not account for the patient's prolonged history of symptoms, which is more consistent with a chronic condition like CF.
**Option B:** This option is incorrect because it does not explain the patient's obstructive curve on PFTs, which is a key feature of CF.
**Option C:** This option is incorrect because it does not consider the patient's genetic predisposition to CF, which is a key factor in the development of this condition.
**Clinical Pearl / High-Yield Fact**
CF is often associated with a failure to thrive in infancy, and a history of meconium ileus or gastrointestinal symptoms should raise suspicion for this condition. Early diagnosis and treatment can significantly improve outcomes in children with CF.
**Correct Answer:** C. Cystic Fibrosis