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Tension Pneumothorax with Evolving Cysts in an InfantAriel Stein, MD,*† Helena Molero, MD,*† Donavon Hess, MD, PhD,*‡ Mark Luquette, MD,*§ Michael B. Pitt, MD*†
*University of Minnesota School of Medicine, Minneapolis, MN†Department of Pediatrics‡Department of Surgery, and§Department of Laboratory Medicine, University of Minnesota Masonic Children’s Hospital, Minneapolis, MN
PRESENTATION
A 5-month-old previously healthy term male infant presents to a rural emergency
department (ED) for a 1-week history of increasing congestion, poor oral intake, and
a temperature of 103°F (39.4°C). He is being treated with amoxicillin for presumed
pneumonia. His examination in the ED is significant for scattered rhonchi andmild
dehydration. His chest radiograph reveals inflammatory changes without a focal
infiltrate (Fig 1). However, because this is his fourth presentation to the ED during
this illness, he is admitted for observation. During the next 2 days his respiratory
distress and tachypnea progressively worsen. On day 3 of his hospitalization he begins
having episodes of desaturation and worsening retractions refractory to oxygen via
low-flow nasal cannula. His examination at this time is significant for diffuse rhonchi
throughout both lung fields with decreased air entry at the lung bases. Because his
clinical status is deteriorating, he is transferred to a higher level of care.
On arrival at the referral center he is lethargic, with decreased breath sounds and
persistent desaturations. A respiratory swab polymerase chain reaction is positive for
respiratory syncytial virus (RSV). His chest radiograph reveals a large right-sided
tension pneumothorax (Fig 2). A pigtail chest tube is emergently placed, and his work
of breathing improves. Within 2 days he is no longer requiring supplemental oxygen.
The medical team is unable to successfully put the chest tube to water seal, however,
because each time it is sealed there is a rapid re-accumulation of his pneumothorax.
After several unsuccessful attempts, his chest tube is placed back to suction and he is
airlifted, via helicopter, to a pediatric tertiary care center for further evaluation, now 11
days after his initial presentation. His chest radiograph just before transfer reveals a
well-positioned chest tube with interval decrease in the size of the pneumothorax.
On arrival at the tertiary care center he is well appearing, with no increased work of
breathing, and is saturating 97% to 100% on room air. His lung sounds are clear
bilaterally, but an air leak is auscultated on inspiration. He has no crackles, wheezes, or
rhonchi. Chest radiography is repeated to verify the position of the chest tube and
incidentally reveals a large cystic-appearing lesion in his right lung that has not been
previously described (Fig 3). Computed tomography of the chest is performed that
reveals multiple air-filled cystic lesions in the right upper lobe of the lung as well as a
persistent right-sided pneumothorax (Fig 4). Surgery and pulmonology are consulted
for co-management. On day 17 of his cumulative hospitalization he undergoes wedge
resection of the right upper lobe of his lung without complications. Samples of the
cystic lesions are sent to the pathology laboratory to confirm the diagnosis.
AUTHOR DISCLOSURE Drs Stein, Molero,Hess, Luquette, and Pitt have disclosed nofinancial relationships relevant to thisarticle. This commentary does not contain adiscussion of an unapproved/investigativeuse of a commercial product/device.
ABBREVIATIONS
CPAM congenital pulmonary airway
malformation
ED emergency department
RSV respiratory syncytial virus
e42 Pediatrics in Review
VISUAL DIAGNOSIS
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DIAGNOSIS
The diagnosis of air leak secondary to rupture of a functional
alveolar bleb, likely due to proximal mucus plugging in the
course of RSVbronchiolitis, was confirmedby pathology (Fig 4).
DISCUSSION
Spontaneous pneumothorax in children outside of the
newborn period is exceedingly rare, with an estimated
prevalence of only 1 in every 10,000 hospitalized children.
The bulk of reported cases are secondary pneumothoraces
due to an acute infection, trauma, or congenital malformation.
(1) In our case, we initially considered a congenital malfor-
mation such as congenital pulmonary adenomatoid mal-
formation (CPAM), given the well-defined cystic lesions on
imaging. CPAMs are the most common form of congenital
parenchymal lung malformations, with an estimated inci-
dence of 1 in 11,000 to 1 in 35,000 live births. (2) Most
CPAMs are diagnosed prenatally during routine 20-week
ultrasonography, and complications may include hydrops
fetalis, recurrent infections in childhood, or malignant
transformation. We reviewed prenatal ultrasonography of
this patient, and there were no signs of lung lesions, and
neither were these lesions visible on previous radiographs. In
addition, spontaneous pneumothorax is a rarely described
comorbidity of CPAM. This was definitively ruled out with
histologic examination of the surgical specimen.
Also on the differential diagnosis was postinfectious
pneumatocele. A pneumatocele is a thin-walled air-filled cyst
in the lung parenchyma, sometimes seen in children sec-
ondary to a severe pulmonary infection, most commonly
Staphylococcus aureus pneumonia. It develops when the
necrotic airway forms a cystic lesion connected to the
bronchial tree. Similar to the ball valve physiology described
later herein, air gets trapped in this lesion, causing hyper-
inflation of the cyst and resulting pneumothorax. (3) His-
tologically, samples obtained from these patients reveal
necrotic debris and multinucleated giant cells. (4) Children
with this condition are generally quite ill with hypoxic re-
spiratory failure requiring aggressive management in an
ICU setting. (5) Because this patient had a relatively short and
mild preceding illness, pneumatocele was less likely, and it
was ruled out by histologic analysis.
This case is remarkable for the abrupt change in the
appearance of the radiograph before and after transfer to the
tertiary care center. We considered the possibility that air
transport contributed to the change. As explained by Boyle’s
law, lower barometric pressure at high altitude causes
Figure 1. Anteroposterior and lateralchest radiographs on hospital day 1show patchy, predominantly perihilarairspace opacities, consistent withviral inflammatory/reactive airwaydisease. No lobar consolidation. Nopneumothorax.
Figure 2. Anteroposterior chest radiograph on hospital day 4 shows alarge right-sided tension pneumothorax with tension physiology.
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volume expansion, which could unmask a more significant
lesion than had been previously identified. (6)(7) Although
helicopters travel at a lower altitude than fixed-wing transport
(10,000 ft vs 20,000–30,000 ft), there are predictable
changes in oxygen requirements and lung volumes at this
altitude that could worsen an air leak. (7) However, histologic
analysis revealed a thick wall surrounding the lesion, sug-
gesting an inflammatory reaction rather than a simple air
leak. In addition, the chest tube, set to suction, was func-
tioning properly and should have prevented expansion of an
intrapulmonary lesion. (7)
RSV infection was most likely the inciting event that led to
his intraparenchymal cysts and persistent air leak. Bron-
chiolitis is the most common lower respiratory tract infection
in children younger than 2 years. The incidence is estimated to
be 11.4 to 19.6 cases per 100 children before age 1 year. (8) RSV
is the most common cause. (9) Although case reports suggest
that spontaneous pneumothorax secondary to viral lower re-
spiratory tract infection occurs with an estimated prevalence of
0.6%, none were treated with surgical intervention. All re-
ported cases resolved with either needle thoracentesis or chest
tube placement. (1)(8)(9)(10)(11)
Histologic examination of the resected lung specimen
identified an air-filled cavity bordered by reparative tissue
(foamy macrophages) and foreign body giant cells (Fig 5).
There was no epithelial lining in the cavity, adjacent smooth
muscle wall, or satellite cysts, which definitively ruled out
CPAM. Although these findings were nonspecific, the results
point to a reaction that can be seen when the airway responds
to a foreign body. Similar to a foreign body in the airway,
mucus plugs can cause lung injury by a ball valve effect.
Figure 4. Contrast computed tomography of the chest on hospital day12 shows multiple air-filled cysts in the right upper lung with right-sidedpneumothorax.Figure 3. Anteroposterior chest radiograph on hospital day 11 shows a
right-sided moderate pneumothorax with a pigtail chest tube in place.Circular lucencies concerning for cystic/cavitary lesions are seen in theright lung.
Figure 5. 1, A cavity (white space on left) lined by foamy macrophages(magnified in inset). 2, Immunostain for KP-1, a macrophage marker(brown areas positive), shows a thick band of positive cells, correspondingto the foamy macrophages, lining the cavity. 3, Immunostain forcytokeratin, a marker of epithelium, shows an inverse pattern to panel 2,with the band of macrophages staining negatively in contrast to thepulmonary parenchyma on the right. 4, Immunostain for smooth muscleactin shows that there is no muscular wall adjacent to the cavity. 5, Cavity(white space on the right) lined by foreign body giant cells.
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During inspiration, the airway expands, allowing air to pass
the obstruction. However, during expiration, the airway
collapses around the obstruction and prevents gas from
escaping. As the cycle repeats, the lung beyond the mucus
plug expands and may lead to pneumothorax. (4)
Patient Course
Our patient had no postoperative oxygen requirement after
he underwent thoracotomy with wedge resection of his right
upper lobe. The chest tube was removed on postoperative day
5, and he was discharged home. He was seen in the clinic the
following week and was well appearing, with clear breath
sounds and no increased work of breathing. He has had no
subsequent recurrences of his symptoms.
Summary• Secondary air leaks and cavity formation as sequelae of
respiratory syncytial virus (RSV) are exceedingly rare.
• Cavitary changes in the lung may develop secondary to
RSV with mucus plugs and air trapping.
• RSV is a frequent cause of pneumonitis in infants that
rarely requires surgical intervention, but it is
important to recognize the possibility of such
complications, which may occur even as the primary
infection is resolving.
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DOI: 10.1542/pir.2018-00622020;41;e42Pediatrics in Review
Ariel Stein, Helena Molero, Donavon Hess, Mark Luquette and Michael B. PittVisual Diagnosis: Tension Pneumothorax with Evolving Cysts in an Infant
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DOI: 10.1542/pir.2018-00622020;41;e42Pediatrics in Review
Ariel Stein, Helena Molero, Donavon Hess, Mark Luquette and Michael B. PittVisual Diagnosis: Tension Pneumothorax with Evolving Cysts in an Infant
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Tension Pneumothorax with Evolving Cysts in an InfantPresentationDiagnosisDiscussionPatient Course
Summary