may be necessary to stent the trachea open to allow gas exchange If significant tracheal compression is present, consideration should be given to the feasibility of biopsy under local anesthesia The anesthesiologist should be apprised of the nature of the tumor, and a bronchoscope should be at hand if a general anesthetic is needed Tissue may be obtained in numerous ways, with the location of the tumor dictating the approach Cystic Mediastinal Lesions The differential diagnosis of cystic mediastinal lesions is large, with the various subtypes arising in predictable anatomic locations of the mediastinum The most common of these lesions will be discussed in this section Thymic cysts are seen in the anterior mediastinum and neck and can cause symptoms if they become infected or hemorrhagic These cysts are lined with ciliated respiratory epithelium, and contain thymic tissue and lymphocytes When enlarged and symptomatic, resection is curative Pericardial cysts arise in the middle mediastinum These are benign, thinwalled cysts lined with mesothelium These lesions are typically asymptomatic and are seen on routine chest films CT scan can confirm the diagnosis, and unless these lesions are symptomatic or large, no intervention is warranted Foregut duplications are cystic or tubular structures found in the posterior mediastinum, and are believed to arise from the original primitive foregut They can frequently be categorized as enteric duplications and cysts lined by intestinal epithelium, bronchogenic cysts lined by respiratory epithelium, or neurenteric cysts with associated vertebral anomalies or having a connection with the nervous system Enteric duplications can be located throughout the neck and mediastinum, though the majority (60%) are intrathoracic Duplication cysts may communicate with the lumen of the airway or esophagus, though most commonly they exist completely separately from the structure of origin Most are asymptomatic at presentation and are discovered incidentally on chest films obtained for an unrelated reason Occasionally, these lesions can enlarge and cause compression of the airways and esophagus, leading to dyspnea, cough, wheezing and in some cases, respiratory distress Rarely, mucosal bleeding in a foregut duplication will create enlargement of the lesion and compression of surrounding structures or hemoptysis/hematemesis if there is connection with a patent lumen Chest x-ray and CT are the main initial diagnostic modalities, with foregut duplications appearing as well defined, tissue-density structures with smooth borders Contrast studies, abdominal ultrasound, and MRI may also be useful adjuncts in the diagnosis of these lesions Definitive treatment consists of complete surgical excision, which can frequently be accomplished without injury to the bronchial or esophageal walls In cases of long tubular foregut duplications that share a wall with the aerodigestive tract, the mucosal lining may be stripped, leaving the common muscular wall intact and preserving the integrity of nearby critical structures If an asymptomatic cystic mediastinal mass is discovered incidentally in the ED, the child may be discharged home for further outpatient evaluation after surgical consultation If any symptoms are present or if there is concern for compression of critical structures, however, the patient should be admitted to the hospital for further workup and management by the surgical team DIAPHRAGMATIC PROBLEMS CLINICAL PEARLS AND PITFALLS Congenital diaphragmatic hernia (CDH) occurs most commonly on the left side Infants with congenital diaphragmatic abnormalities have a 10% to 50% risk of associated anomalies Diaphragmatic hernia may have a similar radiographic appearance to a primary lung lesion such as a CPAM or sequestration Diaphragmatic eventration can be either congenital or acquired, and can present later in infancy or childhood Current Evidence The development of the diaphragm remains incompletely understood and is the result of complex tissue interactions during embryogenesis The diaphragm is composed of four distinct components, the precursors of which begin to form during the fourth week of gestation and fuse centrally to close the pleuroperitoneal canal, with the right side closing before the left Delay or failure of muscular fusion in certain areas of the diaphragm predisposes to weakness or diaphragmatic defects Goal of Treatment Diaphragmatic hernia and dysfunction are concerning because of potential associated abnormalities of the lung and respiratory dynamics, causing symptoms that range from feeding difficulty and persistent or recurrent respiratory infections to overt respiratory distress The primary goals of the clinician are recognition of the diaphragmatic abnormality (which can be difficult to distinguish acutely from a primary lung lesion), administration of respiratory support if needed, and consultation of appropriate subspecialty services for long-term management Congenital Diaphragmatic Hernia Congenital diaphragmatic hernia (CDH) is a defect in the diaphragm with resultant protrusion of abdominal viscera into the chest It is estimated to occur in 1:2,000 to 1:5,000 live births, with approximately 80% to 90% of defects on the left side through the area known as the foramen of Bochdalek Herniation may also occur through the foramen of Morgagni, which lies just posterior to the sternum, comprising 2% or 3% of all diaphragmatic hernias CDH may be associated with a variety of genetic conditions, including trisomy 21, 18, 13, and Cornelia de Lange, Fryns, and Beckwith–Wiedemann syndromes Diaphragmatic hernias may be acquired through traumatic rupture of any portion of the diaphragm and may present in a delayed fashion Information in this chapter will focus largely on diaphragmatic hernias diagnosed in stable older babies and children, who are more likely to present to the ED than those in whom the diagnosis is made in the perinatal period Most children with CDH become symptomatic as newborns, when profound respiratory compromise leads to diagnosis Until recent years, it was believed that the respiratory difficulties of babies with CDH were caused by mechanical compression of the lung by the intestinal viscera herniated through the diaphragmatic opening into the chest It has become clear in recent years, however, that the situation is more complex Lung development in infants with CDH is quite abnormal, with associated pulmonary hypoplasia and abnormal vasculature leading to pulmonary hypertension of varying severity The physiologic consequence of these changes can lead to a life-threatening vicious cycle of hypoxia, acidosis, and intrapulmonary shunting in newborns with this diagnosis Less commonly, CDH may be identified after the neonatal period Older infants and children are less likely to present with this form of respiratory distress but may present with features of bowel obstruction, visceral ischemia, or pleural inflammation arising from sudden shift of abdominal viscera into the chest Clinical Recognition When found in older babies and children, identification is usually by a chest radiograph obtained for nonspecific symptoms such as fever, cough, chest or abdominal pain, or vomiting The presence of loops of intestine above the diaphragm may be seen on the chest radiograph, and the stomach may be confirmed to be in the chest after the passage of a nasogastric tube with the tip in the thorax Loops of intrathoracic intestine on the chest radiograph may be mistaken for pneumonia with pneumatocele formation (Fig 124.12 ) A gastrointestinal contrast study or preferably a chest and abdominal CT scan may provide clarity if the diagnosis is uncertain Potential intestinal or visceral ischemia caused by obstruction and strangulation is one of the reasons operative repair is undertaken emergently Management In the stable but symptomatic patient, surgical repair should be undertaken soon after the diagnosis is made, but may be elective in the asymptomatic patient Because the diagnosis may be made incidentally during evaluation for a condition such as pneumonia, which would increase risk during an elective operation, the timing of surgery must be tailored to the individual situation A pediatric surgeon should be consulted as soon as the diagnosis is suspected, and symptomatic patients should be admitted awaiting repair If a patient is symptomatic from acute ischemia of the herniated viscera, an urgent operation may be required Usually, a transverse or subcostal abdominal incision is used because it permits reduction or resection of compromised intestine or other abdominal viscera and allows for correction of the malrotation that usually accompanies this condition In selected patients, thoracoscopic repair has been performed safely and effectively Foramen of Morgagni Hernias A Morgagni diaphragmatic hernia results from a defect in the anterior diaphragm just behind the sternum Patients are often asymptomatic or present with vague symptoms of abdominal discomfort Substernal or epigastric pain and bowel obstruction resulting from a narrow defect may occur spontaneously or be precipitated by any condition that increases intra-abdominal pressure (Fig 124.13 ) A lateral chest radiograph should clarify the abnormality as anterior and demonstrate that the herniation is not through the esophageal hiatus A contrast esophagram or a CT scan in stable patients should be considered if doubt remains Surgical repair, indicated to prevent incarceration of bowel even in asymptomatic patients, may be performed laparoscopically or through an upper abdominal incision ... during an elective operation, the timing of surgery must be tailored to the individual situation A pediatric surgeon should be consulted as soon as the diagnosis is suspected, and symptomatic patients