Cystic Disease of Lungs, Congenital

• • Uncommon aberrations of respiratory tract development

  • -Starts at 4th week of fetal life

    -Initial phase of airway branching until 16th wk

    -Canalicular phase: Capillaries develop (16th to 26th wk)

    -Alveolar phase: 26th wk on, alveolar air sacs form with type I, II pneumocytes

  • Tracheobronchial atresia (TA)

  • -Can occur at any level

    -May involve isolated or multiple areas

    -Diffuse disease is fatal

    -Isolated bronchial atresia results in bronchus with blind pouch leads to compression of surrounding lung and emphysematous changes

    -Anomalous tracheal or esophageal bronchi and diverticular are related diseases

  • Bronchogenic cysts (BC)

  • -Abnormal budding of foregut may result in formation of BC

    -Commonly occur in pulmonary hilum or mediastinum, occasionally pulmonary parenchyma

    -Usually single, lined by cuboidal respiratory epithelium, preferentially in lower lobes

    -Cysts generally thin walled, occasionally with cartilage

    -May communicate with tracheobronchial tree

    -Known to enlarge rapidly and rupture causing tension pneumothorax

  • Bronchopulmonary dysplasia (BPD): Cluster of diseases includes pulmonary agenesis, aplasia, and primary and secondary hypoplasia

  • -Unilateral agenesis occurs when 1 lung and vessels fail to develop

    -Pulmonary aplasia: Blind bronchial tumor stump exists and soils normal lung with secretions

    -Pulmonary hypoplasia: Low radial alvelolar count and low lung to body weight ratio without inciting cause

    -Secondary pulmonary hypoplasia: Occurs due to fetal or maternal abnormalities such as congenital diaphragmatic hernia, oligohydramnios, Potter syndrome, abnormal bone development

  • Pulmonary sequestration (PS)

  • -Abnormal budding of foregut leading to lung parenchyma without bronchial communication

    -Can be intralobar (85%) or extralobar

    -Often have systemic blood supply from abdominal aorta, 96% drain into pulmonary venous system

  • Cystic adenomatoid malformation (CAM)

  • -Overgrowth of terminal bronchiolar structures lined by respiratory epithelium with disorganized elastic connective tissue and smooth muscle

    -Solid structures interspersed with cysts resembling immature alveoli

  • Congenital Lobar Emphysema (LE)

  • -Hypoplastic bronchial cartilage in 25-75% of patients; increased alveoli number in 37% (polyalveoli)

    -Neonates with prolonged vent support may develop LE from catheter trauma and barotraumas, affecting right lower lobe (RLL)

Epidemiology

• • BPD: 50% have associated cardiac anomalies

  • PS: Left lung affected 58% of time

  • LE: Left upper lobe (LUL) most commonly involved, then right middle lobe (RML)

Symptoms and Signs

• • Often presents early in life

  • Some remain occult until adulthood

  • TA: Neonates present with intractable cyanosis with normal larynx on intubation

  • Isolated bronchial atresia: Wheezing, stridor, pulmonary infections due to mucocele formation and compression of normal lung

  • BC: Mediastinal present with airway compression, parenchymal present with pulmonary infection

  • BPD (agenesis): Neonates present with tachypnea and cyanosis

  • BPD: Some patients present in childhood; dyspnea and wheezing and tracheal deviation toward side of agenesis

  • BPD (hypoplasia): Presents in neonates with tachypnea and hypoxemia resistant to oxygen; persistent fetal circulation

  • PS: Presentation ranges from asymptomatic lower lobe masses to recurrent lower lobe infections due to seeding from pores connected to normal lung, rarely hemoptysis, congestive heart ...