Intralobar sequestration of the lung is a congenital anomaly: anatomopathological analysis of four cases diagnosed in fetal life.

The origin of intralobar sequestration of the lung (ILS)-whether congenital or acquired--has often been controversial, since firm anatomical evidence of prenatal origin has been sparse. We describe four cases in which anomalous arterial supply from the aorta to abnormally echogenic lower lung lobes was demonstrated on routine antenatal ultrasound examination, and the diagnosis of ILS was subsequently confirmed by postmortem examination including bronchography of the fetuses at between 20 and 23 wk. One right-sided lesion was supplied from a branch of the coeliac axis, and three left-sided lesions were supplied from the thoracic aorta. In two cases, the arterial supply was shown to be multiple. All lesions were situated in the lower lobes. They showed a cystic transformation of the affected lung tissue which was histologically indistinguishable from cases diagnosed as congenital cystic adenomatoid lesion (CCAM) at the same gestational age, but clearly different from that seen in bronchial obstruction due to laryngeal stenosis at that age. Similar vascular lesions have been reported in otherwise normal lungs. The character of the anomalous arterial vessels is consistent with origin from the embryonic splanchnic plexus. The precise sequence of pathogenetic events is unclear but there appears to be a close relationship of this condition not only with CCAM but also with the condition of anomalous arterial supply to the lower lobe.