Congenital Lung Malformations

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Overview & Embryology - Tiny Lungs, Big Trouble

  • Congenital Lung Malformations (CLMs): Spectrum of structural defects in lung parenchyma, airways, or vasculature due to abnormal development.
  • Embryology:
    • Origin: Aberrations in foregut differentiation (tracheobronchial diverticulum).
    • Mechanism: Disrupted lung bud development & branching morphogenesis.
    • Timing: Errors during embryonic, pseudoglandular, canalicular, saccular, or alveolar stages.
  • Common Features:
    • Often detected prenatally (ultrasound).
    • May cause neonatal respiratory distress. Congenital Lung Malformations: Types and Characteristics

⭐ Most Congenital Lung Malformations (CLMs) are detected prenatally via ultrasound or present with respiratory distress in the neonatal period or early infancy.

CPAM (Congenital Pulmonary Airway Malformation) - Cystic Chest Chaos

  • Hamartomatous lesion; abnormal branching of immature bronchioles & alveoli.
  • Stocker Classification (Types 0-4):
    • Type 1: Most common (~65%), large cysts >2 cm.
    • Type 2: Small cysts <2 cm; associated anomalies.
    • Type 3: Microcystic/solid; poor prognosis if large.
  • Presentation: Neonatal respiratory distress, recurrent infections, or asymptomatic.
  • Diagnosis: Prenatal USG; postnatal CXR (cysts, shift), CT definitive. Congenital Lung Malformations: Types and Characteristics
  • Management: Surgical resection for symptomatic; elective for asymptomatic (infection/malignancy risk).

⭐ CPAM Type 1 (large cysts >2 cm) is the most common type and carries a risk, albeit low, of developing pleuropulmonary blastoma.

BPS (Bronchopulmonary Sequestration) - Rogue Lung Raiders

Pulmonary Sequestration Types: Intralobar and Extralobar

  • Non-functional lung tissue; lacks normal communication with the tracheobronchial tree.
  • Key feature: Anomalous systemic arterial supply, typically from thoracic or abdominal aorta.
  • Two main types:
    • Intralobar (ILBPS): More common (~75-85%). Located within normal lung lobe/pleura. Venous drainage usually to pulmonary veins. Presents later (childhood/adulthood) with recurrent infections.
    • Extralobar (ELBPS): Less common (~15-25%). Has its own pleural covering. Venous drainage to systemic veins (e.g., azygos, hemiazygos, IVC). Often diagnosed in neonates (respiratory distress); associated with other congenital anomalies.

⭐ The hallmark of Bronchopulmonary Sequestration (BPS) is its anomalous systemic arterial supply, typically from the thoracic or abdominal aorta, and lack of communication with the tracheobronchial tree.

📌 Mnemonic: Intralobar = Inside lung, Infections later; Extralobar = External pleura, Early presentation, Extra anomalies.

CLE & Bronchogenic Cysts - Air Traps & Hidden Pockets

  • Congenital Lobar Emphysema (CLE):
    • Progressive lobar overinflation; air trapping.
    • Cause: Bronchial cartilage defect (most common).
    • Sx: Neonatal respiratory distress.
    • Dx: CXR (hyperlucency, mediastinal shift).
    • Rx: Symptomatic: lobectomy.

    ⭐ Congenital Lobar Emphysema (CLE) most frequently involves the Left Upper Lobe (LUL), causing progressive hyperinflation and potential mediastinal shift, requiring urgent surgical lobectomy in symptomatic neonates.

  • Bronchogenic Cysts:
    • Foregut anomaly; abnormal tracheobronchial budding.
    • Location: Mediastinum, intrapulmonary.
    • Sx: Asymptomatic; or compression (distress), infection.
    • Dx: CXR (round opacity); CT.
    • Rx: Surgical excision if symptomatic/risk. CXR: Congenital Lobar Emphysema with LUL hyperinflation

Pulmonary Hypoplasia & Agenesis - Lungs Left Behind

  • Agenesis: Complete absence of lung tissue.
    • Bilateral lethal; unilateral variable.
  • Hypoplasia: Incomplete lung development (↓ alveoli, airways, vessels).
    • Causes respiratory distress.

⭐ Pulmonary hypoplasia is critically linked to conditions causing thoracic compression (e.g., Congenital Diaphragmatic Hernia - CDH) or prolonged oligohydramnios (e.g., Potter sequence).

  • Associations: CDH, Potter sequence, skeletal dysplasias.
  • Dx: CXR, CT. Chest X-ray: Unilateral Pulmonary Agenesisoka

High‑Yield Points - ⚡ Biggest Takeaways

  • CPAM (Congenital Pulmonary Airway Malformation) is the most common type; Type 1 (large cysts) is most frequent.
  • Pulmonary Sequestration features non-functional lung tissue with systemic arterial supply.
  • Congenital Lobar Emphysema (CLE) leads to progressive lobar hyperinflation and neonatal respiratory distress.
  • Bronchogenic Cysts are typically mediastinal; can cause airway compression.
  • Prenatal ultrasound often detects; CT scan confirms and details postnatally.
  • Surgical resection is the mainstay for symptomatic lesions and CPAM due to malignancy risk (e.g., pleuropulmonary blastoma).

Practice Questions: Congenital Lung Malformations

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