Congenital intraluminal tracheal cyst causing an obstructed left lung in a newborn

Intraluminal tracheal or bronchial cysts are rare. We present a congenital cyst of the distal trachea which caused obstruction of the left main-stem bronchus. The chest radiograph obtained at birth showed an expanded, irregularly opaque left lung. Within several hours, the opacity cleared and the lung became markedly hyperexpanded. The cyst ruptured spontaneously with resolution of the symptoms.