Pulmonary sequestration is a rare congenital malformation of the lung.
Features of pulmonary sequestration:
(1) segment or lobe of dysplastic lung
(2) no communication with the tracheobronchial tree of the normal lung
(3) anomalous arterial and/or venous supply
A sequestration is usually unilateral but occasionally can be bilateral. It may also be located with the abdomen (ectopia).
Types:
(1) extralobar (separate visceral pleura and venous drainage to a systemic vein)
(2) intralobar (within the visceral pleura of a functioning lung and venous drainage to the pulmonary vein)
Many patients are asymptomatic. Symptoms may occur if there is:
(1) heart failure from right-to-left shunt
(2) spontaneous hemorrhage
(3) compression of adjacent lung causing respiratory distress
(4) other congenital malformations
Pulmonary sequestration may present in a fetus with hydrops, pleural effusion and pulmonary hypoplasia.
Appearance on imaging studies:
(1) cyst
(2) lung mass
(3) lamellar lesion
(4) an encapsulated lesion with air-fluid level
(5) bronchiectasis
(6) isolated emphysematous bleb
Differential diagnosis:
(1) hydatid cyst
(2) lung tumor
(3) bronchogenic cyst
(4) cystic adenomatoid malformation
(5) congenital lobar emphysema
