D2I2.
congenital

Pulmonary sequestration

A sequestration is a medical condition wherein a piece of that ultimately develops into lung tissue is not attached to the pulmonary blood supply, as is the case in normally developing lung. This sequestered tissue is therefore not connected to the normal bronchial architecture, and fails to function in, and contribute to, respiration of the organism.

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Plain-language summary adapted from Wikipedia. Not medical advice.