CLASSIFICATION OF

BRONCHOPULMONARY SEQUESTRATION

A. Two types are described based upon the extent of pleural covering:

• Intra-Lobar Sequestration
• Shares a visceral pleural surface with normal lung tissue (located within the substance of a lung lobe).
• Usually presents in adulthood with acute or recurrent infections.
• Three times more common than extralobar sequestration.
• 14% of patients with intralobar BPS have other associated anomalies.
• Extra-Lobar Sequestration
• Has its own separate pleural covering, and is therefore separate from the rest of the lung.
• Usually presents in infancy because of associated congenital abnormalities or pulmonary hypoplasia.
• May rarely present subdiaphragmatically or intraabdominally (1,2).
1. chest, including the pericardial sac,
2. or in the abdomen - may present as a retroperitoneal mass or cyst, which may lie next to the stomach or communicate with it. The arterial supply is nearly always from the descending aorta and therefore represents a persistence of primitive splanchnic arteries that supply the early foregut. Venous drainage is typically through the azygos system or the inferior vena cava; however, in about 25% of cases the venous drainage is through the pulmonary veins. Intra-abdominal BPS appears in approximately 10% of cases of extralobar BPS, and 90% of them occur on the left side.
• Approximately 60% of fetuses with extralobar BPS have associated anomalies, including diaphragmatic anomalies (28%), other pulmonary anomalies (10%) and cardiac malformations (8%).

· 1974 Sade (4) showed that BPS has diverse variant forms, including bronchopulmonary and vascular related malformations. He proposed the term sequestration spectrum. At one end of the spectrum is anomalous blood supply to a normal lung while at the other end is abnormal lung tissue without anomalous vascular supply.

Between these two extremes is a large group of variant BPS that encompasses anomalies ranging from intrapulmonary sequestration to extrapulmonary sequestration with or without gastrointestinal communications, i.e. bronchopulmonary foregut malformations.

B. Three types are proposed (3) to define more clearly optimal management:

• Type I
• Small asymptomatic lesion, barely visible on chest X-ray but confirmed on CT scan or thoracic MRI.
• Two subtypes can be identified according to its solid or cystic nature.
• Type 2
• Medium sized lesion (<1/2 of the pulmonary field) visible on chest X-ray with / without associated clinical signs.
• Type 3
• Hemithoracic lesion + mediastinal shift causing respiratory failure. This type always requires surgical intervention.

The optimal management of types 1 and 2 is still controversial.

REFERENCES

1. Weinbaum PJ, Bors-Koefoed R, Green KW et.al. Antenatal sonographic findings in a case of intra-abdominal pulmonary sequestration. Obstet Gynecol 1989;73(5):860-861.
2. Davies RP, Ford WDA, Leqiesne GW et.al. Ultrasonic detection of subdiaphragmatic pulmonary sequestration in utero and postnatal diagnosis by fine-needle aspiration biopsy. J Ultrasound Med 1989;8:47-49.
3. Langer B, Donato L, Riethmuller C et.al. Spontaneous regression of fetal pulmonary sequestration. Ultrasound Obstet Gynecol 1995;6:33-39.
4. Sade RM, Clouse M, Ellis FH. The spectrum of pulmonary sequestration. Ann Thorac Surg 1974; 18: 644-655.