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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.