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4. Pulmonary sequestration
On the video images an aberrant pulmonary artery is seen suppling the density. The CT images combined with the history are diagnostic of pulmonary sequestration. Pulmonary sequestration is the aberrant formation of segmental lung tissue that has no connection with the bronchial tree or pulmonary arteries (1). The estimated incidence is 0.1%. There are two types: intralobar sequestration (ILS) and extralobar sequestration (ELS). The abnormal lung tissue is located within the visceral pleura of a pulmonary lobe in ILS, whereas the ELS has its own visceral pleura. ILS accounts for 75-85% of sequestrations. Sequestration preferentially affects the lower lobes. 60% of ILS affect the left lower lobe, and 40% the right lower lobe. ELS almost always affect the left lower lobe, however, about 10% of can be subdiaphragmatic.
ILS is closely connected to the adjacent normal lung and do not have a separate pleura. In ILS, venous drainage commonly occurs via the pulmonary veins, but can occur through the azygous-hemiazygous system, portal vein, right atrium or inferior vena cava.
ELS is separated from any surrounding lung by its own pleura. Venous drainage most commonly through the systemic veins into the right atrium (but is variable).
Which of the following is true regarding pulmonary sequestration in adults? (Click on the correct answer to proceed to the fifth and final page)