Pulmonary Sequestration

  • Etiology: nonfunctional dysplastic pulmonary parenchyma lung tissue not connected to bronchial tree or pulmonary artery, comes from accessory lung bud, if it develops early before pleura develops is intralobar, if it develops later after pleura develops is extralobar
  • Imaging: most commonly in lower lobes (left > right), arterial blood supply from subdiaphragmatic aorta / celiac trunk / splenic artery, only contain air when infected, 15% are ectopic – suprarenal / mediastinum / pericardial / neck
    — Intralobar (75%) – no separate pleural investment (within visceral pleura), pulmonary venous drainage to left atrium (normal drainage)
    — Extralobar (25%) – separate pleural investment (outside visceral pleura), systemic venous drainage to vena cava or azygous vein, 15% ectopic – suprarenal / mediastinal / pericardial / neck
  • Clinical: intralobar present in older child with recurrent lower lobe pneumonias, 60% of extralobar sequestrations are associated with congenital abnormalities (congenital diaphragmatic hernia, cardiac anomalies, congenital pulmonary airway malformation = hybrid lesion)

Cases of Pulmonary Sequestration

CXR and MRI of pulmonary sequestration
CXR shows a large round opacity in the left lower lobe that abuts the diaphragm. Coronal T1 MRI with contrast of the chest shows a uniformly enhancing mediastinal mass that extends into the retrocrural regions of the chest bilaterally and that has a feeding vessel arising from the aorta.
Gross pathological image of extralobar pulmonary sequestration
Gross pathological images show a right-sided subdiaphragmatic / suprarenal mass similar in appearance to the lung above it (above left). When the aorta was opened (above right), the orifice of an arterial vessel supplying the mass was seen coming off of the aorta just above the tip of the upper hemostat on the right side of the aorta. The relationship of the feeding vessel off of the aorta to the mass is more clearly demonstrated on the specimen image (below).