"Horseshoe" lung: report of five new cases

Abstract

Case MaterialWe identified five patients at the Hospital for Sick Children in Toronto with the horseshoe lung anomaly and reviewed their chest radiographs, angiographic studies in four patients, and pathologic material in four patients, including a postmortem bronchogram in one patient.The diagnosis of horseshoe lung anomaly was made from pulmonary angiography in four patients and confirmed at autopsy in three of these, from pulmonary angiography alone in one patient, and from autopsy findings alone in one patient. Four of the five patients became symptomatic in the neonatal period. One of these had complex congenital heart disease with hypoplastic left heart syndrome, severe coarctation of the descending aorta, and double-outlet right ventricle and died in the neonatal period. The four other patients had features of scimitar syndrome. Three of these presented in early infancy with respiratory distress, believed to be at least partly secondary to congestive heart failure, and died in the first few months of life. The fifth patient, who also had features of the scimitar spectrum, was asymptomatic and was investigated angiographically after a chest radiograph showed dextrocardia, small right lung, and abnormal pulmonary vascular markings. She has subsequently remained asymptomatic.Seven additional patients with horseshoe lung anomaly have been reported in the world literature [1-6].

Scimitar syndrome: incidence, treatment, and prognosis

“…The horseshoe or crossover lung anomaly may occur, as in patient 4, and is another common malformation associated with scimitar syndrome [6,8,9,21]. Airway anomalies, although common, do not seem to be major factors for symptoms.…”

Lungs

“…Horseshoe lung is an anomaly in which parts of the right and left lungs are fused together by a tongue of parenchyma posteroinferior to the pericardial reflection at the cardiac apex (Freedom et al 1986). It is usually associated with scimitar syndrome, which consists of partial anomalous pulmonary venous drainage of the right lung, right lung hypoplasia, dextroposition of the heart, and anomalous systemic arterial supply from the aorta to the right lung.…”

“…Up to 2001, Männer et al (2001) described that almost 40 cases had been reported in the literatures since the first report by Spencer (1977). Regarding the fused part of these two lungs, two patterns have been reported: one in which the fusion was within the isthmus, and the other in which the fused tissue was separated by a fissure-like layer of visceral pleura (Freedom et al 1986). The right lung has often been reported as hypoplastic and lacking normal identifiable fissure and lobes, whereas the left lung has usually had a more normal appearance (Freedom et al 1986).…”

“…Regarding the fused part of these two lungs, two patterns have been reported: one in which the fusion was within the isthmus, and the other in which the fused tissue was separated by a fissure-like layer of visceral pleura (Freedom et al 1986). The right lung has often been reported as hypoplastic and lacking normal identifiable fissure and lobes, whereas the left lung has usually had a more normal appearance (Freedom et al 1986). Regarding the bronchial pattern, the abnormality has also been observed on the right side.…”

“…Arterial supply to the right lung is provided both by the mediastinal right pulmonary artery and by an anomalous arterial supply originating from the descending aorta. The so-called "horseshoe part" is supplied by a branch of the right pulmonary artery and contributions from the left pulmonary artery (Freedom et al 1986). Some variation cases of horseshoe lung, such as those with left lung hypoplasia (Ersöz et al 1992;Oguz et al 2009;Jeewa et al 2010;Salerno et al 2010;Yildiz et al 2012), diaphragmatic herniation of the liver (Čičak et al 2010), and facio-auriculo-vertebral sequence (D' Alessandro et al 2006) have also been reported recently.…”