What is the management approach for a Congenital Pulmonary Airway Malformation (CPAM) cyst in the lung?

Management of Congenital Pulmonary Airway Malformation (CPAM)

Fetal CPAM with Hydrops

For fetal CPAM causing hydrops fetalis, immediate intervention is required: macrocystic lesions should undergo needle drainage or shunt placement, while microcystic lesions should be treated with maternal corticosteroids as first-line therapy. 1

Fetal Intervention Strategy

• Macrocystic CPAM: Perform needle drainage or thoracoamniotic shunt placement to decompress the cyst and restore venous return 1
• Microcystic (predominantly solid) CPAM: Administer maternal corticosteroids as first-line treatment; in utero resection may be considered if corticosteroids fail 1
• Hydrops occurs in only 5% of fetuses with CPAM but carries a poor prognosis without treatment 1
• The pathophysiology involves mediastinal shift impairing venous return and cardiac output, with esophageal compression causing polyhydramnios 1

Postnatal CPAM Management

For postnatal CPAM diagnosed in children or adults, surgical resection at the time of diagnosis is recommended due to the risk of malignant transformation (0.7-8%) and recurrent respiratory infections. 2, 3, 4

Indications for Surgical Resection

• Symptomatic CPAM: Immediate surgical resection is indicated for patients presenting with breathlessness, pneumothorax, recurrent pulmonary infections, fever, or hemoptysis 2
• Asymptomatic CPAM: Surgical resection is recommended to eliminate the risk of malignancy and infection, even in asymptomatic cases 2, 3
• Type 1 CPAM carries the highest malignancy risk, with mucinous cell clusters (premalignant lesions) present in 75% of cases 3
• The risk of pleuropulmonary blastoma, though rare, is a critical consideration in young children with lung cysts 5

Surgical Approach

• Standard cases: Non-anatomical wedge resection or lobectomy using video-assisted thoracoscopic surgery (VATS) is the preferred approach 2
• Giant multilobar CPAM: Pneumonectomy may be required in rare cases involving an entire lung, though this carries significant morbidity including pulmonary hypertension, prolonged ICU stay, and potential tracheomalacia/bronchomalacia 6
• Tube thoracostomy should be performed first if pneumothorax is present, followed by definitive surgical resection 2

Critical Pitfalls to Avoid

• Do not adopt a "watch and wait" approach for Type 1 CPAM, as 75% contain mucinous cell clusters with malignant potential 3
• Do not delay resection in symptomatic patients, as complications including pneumothorax and infection can be life-threatening 2
• Do not assume all cystic lung lesions are benign: pleuropulmonary blastoma can be clinically and radiographically indistinguishable from benign congenital cysts and requires histopathologic examination for differentiation 5

Post-Resection Surveillance

• Close monitoring is required even after surgical resection due to the persistent mild but definitive risk of malignancy 2
• Obtain detailed family history to identify hallmarks of pleuropulmonary blastoma syndrome: lung cysts, cystic nephroma, childhood cancers, ovarian tumors, intestinal polyps, or thyroid hyperplasias 5
• Patients with multifocal/bilateral lung cysts or family history suggestive of PPB syndrome require particularly vigilant follow-up 5

Special Considerations for Neonates

• Premature infants with giant CPAM may require emergent cesarean section if mediastinal shift, pericardial effusion, or decreased fetal movement develops 6
• Expect pulmonary hypertension, prolonged ventilator dependence, and potential need for extracorporeal membrane oxygenation (ECMO) in severe cases 6
• Bronchoscopy should be performed to evaluate for tracheomalacia/bronchomalacia, which may require aortopexy or tracheostomy 6