Question

A 5 year old boy with a history of congenital heart disease post Fontan procedure presents with worsening cough, dyspnoea, hypoxia. Suspecting airway obstruction, a bronchoscopy is performed. Which of the following findings is most characteristic of plastic bronchitis?

• A. Caseaous necrotic material obstructing the bronchus
• B. Thick, yellow green mucus plugging the segmental bronchi
• C. Large, rubbery, branching cast conforming to bronchial architecture
• D. Inflamed mucosa with bleeding and ulceration of bronchial wall

Hint:

Plastic Bronchitis: Child post-Fontan operation + acute severe asphyxiation/airway occlusion $\rightarrow$ Expectoration/bronchoscopy of branching, rubbery, tree-like casts (due to pulmonary lymphatic leakage).

Answer 1

The Correct Option is C

Concept:
Plastic bronchitis (PB) is a rare and potentially fatal disorder characterized by the formation and expectoration of large, cohesive, cohesive, branching casts that conform to the exact branching architecture of the tracheobronchial tree.
It is a well-recognized, severe complication following single-ventricle palliation surgeries, particularly the Fontan procedure.
Explanation:
• Following a Fontan procedure, elevated systemic venous pressures and altered thoracic lymphatic dynamics lead to lymphatic hypertension and abnormal lymphatic leakage directly into the airway lumen.

• In the presence of high pulmonary venous pressures and lymphatic leakage, proteinaceous, chylous, and fibrin-rich lymph fluid coagulates inside the airways.

• These solidified secretions form large, thick, rubbery, branching casts that precisely mirror the shapes of the segmental and subsegmental bronchial branches ("casts of the bronchial tree").

• These cohesive casts cause critical mechanical obstruction of major airways, precipitating acute respiratory failure, atelectasis, severe dyspnea, and life-threatening asphyxiation.

• Rigid bronchoscopy provides immediate life-saving therapeutic cast removal, while definitive diagnosis and management involve dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) followed by lymphatic intervention/embolization.
Final Answer:
The pathognomonic bronchoscopic finding of plastic bronchitis is the presence of large, rubbery, cohesive branching casts that replicate the bronchial architecture.