Horseshoe lung--a case report with unusual bronchial and pleural anomalies and a proposed new classification

Adult congenital horseshoe lung with bilateral pulmonary sequestration: A case report

Horseshoe lung (HL) is an infrequent congenital lung anomaly. Its main feature is that the lower lungs on both sides extend behind the pericardium and fuse across the midline, usually accompanied by pulmonary dysplasia. It is reported that 80% of HL is relevant to the abnormal return of some pulmonary veins from the right lung to the inferior vena cava or right atrium (scimitar syndrome). Most patients are within 5 years old, most commonly within 1 year old, but HL may also have no apparent clinical symptoms or mild symptoms. This case is a 36-years-old adult female who developed left chest pain more than a month ago and continued to worsen for 10 days. The patient also had repeated pulmonary infection with cough and expectoration.

Is horseshoe lung a component of VACTERL spectrum? Case report and review of literature

Horseshoe lung (HL) is a rare congenital anomaly that has been classically associated with Scimitar syndrome. Very few cases have been described in the context of the VACTERL spectrum. We present a case of a newborn girl with mesocardia, tracheoesophageal fistula, and imperforated anus, who required O2 support at birth and during hospitalization. A chest CT angiography revealed a HL as an incidental finding. We suspect that HL and the VACTERL spectrum, are not separated entities but likely a further expansion of VACTERL-associated symptoms. HL might be underdiagnosed in asymptomatic patients as Chest CT angiography is not part of the routine work up for patients with VACTERL association.

A Horseshoe intralobar lung sequestration resection by bilateral Robot-Assisted Surgery

We present the case of a 20-year-old male presenting a right lower intralobar pulmonary "horseshoe" sequestration extending into the left cavity supplied by four aberrant arteries from the thoracic descending aorta. The surgical approach for this exceptional and challenging presentation was based on thorough analysis of the chest CT scan aided by 3D reconstructions. The latter helped us better understand this complex malformation. Surgery was done by robot-assisted bilateral approach with en bloc extraction through the left side.

Two rare cases of horseshoe lung with scimitar syndrome in Vietnam

Horseshoe lung is a rare, congenital, pulmonary anomaly in which the caudal and basal segments of the left and right lungs are joined together. Most cases of horseshoe lung are associated with scimitar syndrome. Horseshoe lung can be diagnosed using pulmonary angiography, showing that the isthmus of the pulmonary parenchyma crosses the midline into the contralateral side. The isthmus parenchyma is typically supplied by the hypoplastic pulmonary artery. Clinical symptoms, therapeutic methods, and prognosis depend on the incidence of pulmonary hypertension, heart failure, recurrent pneumonia, and other combinations of congenital malformations. In this article, we describe two cases of horseshoe lung associated with scimitar syndrome and pulmonary malformation.

Horseshoe lung associated with scimitar syndrome

Horseshoe lung is a rare congenital anomaly and mostly accompanied by scimitar syndrome. Most aspects of this complex anomaly can be demonstrated via multidetector CT (MDCT). We present two baby girls who had horseshoe lung associated with right lung hypoplasia and scimitar vein. The chest roentgenograms showed displacement of the heart and mediastinum to the right with smaller right lung. Echocardiography revealed dextroposition, secundum atrial septal defect and bilateral slight peripheral pulmonary stenosis in the first case and dextroposition, severe pulmonary hypertension, secundum atrial septal defect and tricuspid regurgitation in the other one. On thoracic MDCT, the right lung and pulmonary artery were hypoplastic with cardiomediastinal shift to the right. There was an abnormal right pulmonary vein draining into the inferior vena cava on the lower zone of the right lung (scimitar vein). The posterobasal portions of the both lungs were fused through a midline isthmus behind the heart.

Intralobar pulmonary sequestration expanding toward the contralateral thorax: two case reports

Background

Intralobar pulmonary sequestration (ILS) is defined as a portion of parenchyma that is contained within the normal pleural investment of the lung but not connected to the tracheobronchial tree, and supplied by anomalous systemic arteries. As ILS is enveloped within the lobe of the normal lung, it is extremely rare for ILS to invade into the mediastinum. We report two atypical cases of infants with ILS expanded toward the posterior mediastinum and contralateral thorax through the pulmonary ligament.

Case presentation

The first case involved a baby boy diagnosed at 30 weeks gestation with a cystic area in his right lower lobe. A chest computed tomography (CT) scan at 29 days of life showed low-density masses in the right lower lung and posterior mediastinum. A complete thoracoscopic right lower lobectomy was performed at 19 months of age. After ligation of the aberrant systemic artery, the mediastinal mass was pulled into the right pleural cavity. The mass was observed to connect to the right lower lobe mass as a segment of lung parenchyma situated within the normal pleural investment of the lung, and the patient was diagnosed with ILS. The second case involved the detection by chest CT of a left lower lung cystic mass that protruded into the posterior mediastinum and contralateral chest of a one-month-old baby girl. A complete thoracoscopic left lower lobectomy was performed at the age of 18 months, and the cystic mass located in the right thoracic cavity was pulled easily into the left pleural cavity and resected. An anomalous systemic artery was identified and ligated, and the patient was also diagnosed with ILS.

Conclusions

As the pulmonary ligament consists of two layers of mediastinal pleura, lower lung ILS with its visceral pleura covering can, though rarely, protrude into the mediastinum through the pulmonary ligament. Our two extremely rare cases of infants with ILS expanded toward the posterior mediastinum and contralateral thorax were successfully treated using a unilateral thoracoscopic approach. Pre-surgical differential diagnosis of mediastinal masses using contrast-enhanced multiple detector CT is important in informing the appropriate surgical approach.

Pediatric Thoracic Anatomic Variants: What Radiologists Need to Know

Anatomic variants are common incidental findings in pediatric chest imaging and can be mistaken for true underlying pathology, sometimes resulting in unnecessary additional imaging evaluation or invasive procedures. Clear understanding of the imaging characteristics and clinical significance of anatomic thoracic variants is important for accurate diagnosis and avoidance of unnecessary intervention. This article provides an up-to-date review of anatomic variants in the pediatric chest to increase knowledge and aide in timely, correct diagnosis.

Horse-shoe lung-rediscovered via volume rendered images

Horseshoe lung, usually associated with pulmonary venolobar syndrome, is a rare congenital anomaly involving the fusion of the postero-basal segments of the right and left lungs across the midline. The fused segment or the isthmus lies posterior to the pericardium and anterior to the aorta. The associated pulmonary venolobar syndrome involves anomalous systemic arterial supply and anomlaous systemic venous drainage of the right lung. With the advent of MDCT imaging, we can diagnose this rare condition as well all its associated anomalies non-invasively. Volume-rendered techniques greatly simplify the complex anatomy and provide easy understanding of the same.

Horseshoe lung associated with cardiac-type total anomalous pulmonary venous return in a newborn

Horseshoe lung is a rare pulmonary anomaly characterized by fusion of the posterobasal portions of the right and left lung behind the heart anterior to the aorta and the spinal column. This anomaly is almost always associated with lung hypoplasia. The case of a newborn who had horseshoe lung with left lung hypoplasia and cardiac-type total anomalous pulmonary venous return is reported.

Mediastinal lung herniation associated with pulmonary sequestration

Mediastinal lung herniation is a rare condition characterized by protrusion of 1 lower lung through behind the heart into the opposite side of the chest, usually from right to left. We present a case of mediastinal lung herniation associated with pulmonary sequestration, which was confirmed both surgically and pathologically in a 13-year-old girl initially admitted with a diagnosis of pneumonia. Contrast-enhanced computed tomographic images using a multidetector-row computed tomography clearly demonstrated the right lung herniation toward the left and 2 aberrant systemic arteries supplying the sequestered lung mass. These arteries run through the herniated lung from right to left. Additionally, on the basis of pleural anatomy, we discuss herein the difference between a mediastinal lung herniation and horseshoe lung.

The Respiratory System

One of the most critical events of birth is the conversion of the fluid-filled lung, unimportant to fetal intrauterine existence, into a hollow organ distended with air and capable of gaseous exchange sufficient to support life. Indeed, it has been argued that the major determinant of perinatal survival is respiratory function (Wigglesworth and Desai 1982).

The failure to make this conversion adequately may lead, directly or indirectly, to infant death, and the pathologist often needs to assess the contribution made by respiratory inadequacy to the sequence of events leading to death. In the preterm infant, problems are mainly related to pulmonary immaturity and associated therapy. In the mature infant, birth asphyxia primarily results in cerebral damage but can engender significant respiratory complications when associated with aspiration of meconium. Even in stillbirths, where primary pulmonary pathology is rarely a cause of death, lung pathology may provide clues to antecedent events. Poor lung growth and maturation may point to the presence of pathology elsewhere. Consequently, adequate pathological investigation of the fetal or infant respiratory system is critical in any perinatal autopsy.

Prenatal diagnosis of horseshoe lung and esophageal atresia

We present a case of horseshoe lung (HL) and esophageal atresia suspected prenatally on US imaging and confirmed with fetal MRI. Prenatal diagnosis of HL and esophageal atresia allowed for prenatal counseling and informed parental decisions.

Congenital bronchopulmonary foregut malformations: concepts and controversies

This article addresses the scope, etiology, important associations and imaging features of congenital bronchopulmonary foregut malformations. Etiologic concepts, including airway obstruction and vascular anomalies, are highlighted. Technical imaging advances, especially CT and MR, have greatly enhanced our diagnostic abilities in evaluating these lesions; however, thorough and careful assessment of all aspects of the malformation is still necessary. Several specific lesions are discussed in more detail, particularly regarding controversial issues in classification, understanding, imaging and management.

The relationship between scimitar syndrome, so-called scimitar variant, meandering right pulmonary vein, horseshoe lung and pulmonary arterial sling

We report a case in which a meandering right pulmonary vein connecting to the left atrium is associated with hypoplasia of the right lung, horseshoe lung, abnormal pulmonary lobation, and abnormal branching of the pulmonary arteries. We discuss its relationship to the so-called scimitar variant, and to the scimitar syndrome itself.

Prenatal diagnosis of horseshoe lung: contribution of MRI

Horseshoe lung is a very rare pulmonary anomaly that is characterized by an isthmus of lung parenchyma bridging the right and left lungs and extending through the mediastinum. We report on the prenatal diagnosis of such a malformation in a 33-week-gestation fetus. The diagnosis was initially suspected on antenatal ultrasonography performed at 33 weeks and confirmed by fetal MRI and subsequent pathological examination after termination of pregnancy. To our knowledge, this is the first reported case of antenatal diagnosis of horseshoe lung.

Horseshoe lung in association with other foregut anomalies: what is the significance?

The authors present an unusual constellation of foregut anomalies in a newborn boy including horseshoe lung, esophageal atresia (EA) with distal tracheoesophageal fistula (TEF), congenital cystic adenomatoid malformation (CCAM), esophagobronchial fistulae, and a preduodenal pancreas. Horseshoe lung is a rare congenital anomaly in which the left and right lung bases are fused across the posterior mediastinum. The presentation is variable. The association of horseshoe lung with VACTERL anomalies and Bronchopulmonary foregut malformations is reviewed.

Horseshoe lung: report on a new variant--"inverted" horseshoe lung--with embryological reflections on the formal pathogenesis of horseshoe lungs

The term "horseshoe lung" is used to describe a rare congenital anomaly of the lungs that is characterized by the presence of a midline isthmus of pulmonary parenchyma connecting the posterobasal regions of the right and left lungs. Since the introduction of the term horseshoe lung in the 1960's, almost 40 cases have been reported in the literature. In all these cases, the right and left lungs were joined in their posterobasal regions, the situation resembling that found in horseshoe kidneys. Here we present a case of connection between the right and left lungs found during necropsy of a human fetus. In this case, a midline isthmus of pulmonary parenchyma covered by visceral pleura joined the apical regions of the right and left lungs behind the trachea and esophagus. This connection resulted in a "horseshoe"-shaped lung in which the "horseshoe" was turned by 180 degrees compared to classical cases of horseshoe lung. To the best of our knowledge, this is the first report on an "inverted" horseshoe lung. Embryological reflections on the formal pathogenesis of inverted and classical horseshoe lungs are presented.

Horseshoe lung: demonstration by electron-beam CT

Horseshoe lung is a rare pulmonary anomaly characterized by fusion of the posterobasal portions of the right and left lungs behind the pericardial reflection, anterior to the aorta. The majority of reported cases occur in conjunction with scimitar syndrome, including hypoplasia of the right lung, anomalous right pulmonary venous return and systemic arterial supply to the lung. Horseshoe lung is usually diagnosed on pulmonary arteriography when the right inferior pulmonary artery crosses the midline and extends to the left lung base. Bronchography is also diagnostic when the branch of horseshoe portion arises from the right bronchus and passes within the lung parenchyma to midline of the lung tissue. The only described CT finding of horseshoe lung is the contiguity of the right and left lungs behind the heart. Most cases are infants under 12 months of age and CT images are severely hampered by respiration motion artefacts. Such artefacts are minimized by using electron-beam computed tomography, allowing a more detailed CT appearance of horseshoe lung in this case.

Echocardiographic clues and accuracy in the diagnosis of scimitar syndrome

Scimitar syndrome was diagnosed in 27 patients seen between July 1974 and May 1993. All available echocardiograms taken before surgery or death were reviewed. Age at presentation ranged from 1 day to 14 years. Dextrocardia or mesocardia was noted in 70%, atrial septal defect in 70%, and increased right ventricular dimension in 70% of the patients. The ratio of the proximal and distal diameters of the right/left pulmonary arteries were reduced 0.68 +/- 0.17 and 0.66 +/- 0.17, respectively. "Blunting" of the right side of the left atrium was seen in all patients with total anomalous right pulmonary venous drainage and none with partial drainage. Anomalous right pulmonary venous drainage was characterized in 91% of echocardiograms with color flow mapping versus 14% without color flow mapping (p < 0.0002). Aortopulmonary collateral arteries were detected in all four cases in which color flow mapping was performed, but not detected otherwise.

Shoe, scimitar or sequestration: a shifting spectrum

Congenital abnormalities of the tracheobronchial tree are rare causes of recurrent chest infections in childhood. A case is described which shows some typical features of horseshoe lung. More detailed imaging revealed complete separation of the right and left pleural cavities and the malformation represents part of the sequestration spectrum. The case emphasises the need for careful evaluation of the pulmonary arteries, veins, bronchi and oesophagus, particularly prior to surgery.