Nicole Jackson, General Surgery R2
Seattle Children’s Hospital
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Definition
Anatomy and Embryology
Pathology
Clinical Features/Classification
Presentation
Treatment
Complications
Summary
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Previously known as Congenital Cystic
adenomatoid malformation
Rare developmental anomaly of the lower
respiratory tract
Most common congenital lesions of the lung
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First reported case of in 1975 in Sydney, Australia
Right lower lobe CCAM that resulted in in utero
death at 34 weeks of gestation
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Spectrum of cystic and solid lesions of the lung
Over growth of terminal bronchial or
bronchiolar-type tubular structures and a lack of
mature alveoli
Hamartomatous lesions
Result from abnormal branching during
development of the lung
Blood supply from pulmonary circulation
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Previously known as CCAMs and divided into 3
main types, based upon the size of the cyst and
their cellular characteristics
Now classified as CPAMs and two additional
types were added
Each type has a distinct pathologic characteristic
Rare: 1 in 25,000 to 35,000 pregnancies
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Rarest form, 1-3% of cases
Originates from tracheal or bronchial tissue
Cysts are small, containing mucus cells and
cartilage
Diffuse malformation that involves the entire
lung
Gas exchange is severely impaired, affected
infants die at birth
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Most common form of CPAM, 60-70%
Thought to originate from the distal bronchi or
proximal bronchioles
Well-differentiated tissue within the lesions
 Embryonic insult thought to occur some time around
7-10 weeks gestation
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Thin walled cysts 2-10 cm in diameter, may be
multiloculated
95% of cases only one lobe of the lung involved
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15-20% of CPAMs
Bronchial/Bronchiolar type
Multiple cysts 0.5-2 cm in diameter, relatively
uniform cysts, with solid areas that blend into
normal tissue
Resemble dilated terminal bronchioles, separated by
normal alveoli
Other congenital anomalies observed in ~60% of
cases
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5-10% of CPAMs, bronchiolar/alveolar duct type
Excess of bronchiolar structure separated by
small air spaces, resembling late fetal lung
Often very large and can involve entire lobe or
several lobes
Grossly a solid mass
 Mixture of cystic and solid or entirely solid
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10-15% of CPAMs
Large cysts, more peripheral
Consist of nonciliated, flattened, alveolar lining
cells (type 1 and 2 pneumocytes)
Associated with pleuropulmonary blastoma
 Variable, depends on type
 Prenatal
 Development of hydrops
 Neonatal
 Childhood
 Asymptomatic
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Range from incidental findings to massive
pulmonary involvement
Lesions regress in up to 60% of cases, with
spontaneous resolution reported
About 80% of lesions detected before 22 weeks
at routine Second trimester screening Ultrasound
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CPAMs large enough to cause mediastinal shift
can lean to obstruction of IVC and cardiac
compression
Difficult to predict outcome based on prenatal
ultrasound
Macrocytic better than Microcytic lesions
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Up to 2/3 present with respiratory symptoms
 Tachypnea, increased respiratory effort, cyanosis
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Majority are Type 1
Type 2 often diagnosed after birth due to association
with other anomalies
Type 3 may be stillborn or present immediately after
birth with severe, progressive respiratory failure
Type 0 are all lethal at birth
Type 4 can present with pneumothorax
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1/3 diagnosed after neonatal period
Lesions small, often Type 1 or 4
Commonly child with recurrent pneumonia
Spontaneous pneumothorax
 Malignancy should be suspected in child with CPAM
and PTX
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½ of patients with prenatal diagnosis are
asymptomatic at birth
Small proportion develop symptoms within a few
weeks to months of birth
Onset of symptoms usually before 10 months
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Screening US, MRI,CXR, and CT scan,
confirmation only after surgical resection or at
autopsy
For asymptomatic neonates CT recommended
within 4-6 weeks to confirm the diagnosis and
further evaluate the lesion
Plain radiographs often insufficient
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Type 0 – made at autopsy
Type 1 – single lesions with one or a few large cysts,
may be filled with air or have air-fluid levels
Type 2 – similar to type 1, more numerous small
cysts appear more homogenous, “bubbly”
appearance
Type 3 – large, solid, homogenous mass, usually
mediastinal shift with hypoplasia of contralateral
lung
Type 4 – may show pneumothorax, signs of infection
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Size of lung mass size correlates with outcome
 Threshold value > 5.2 cm
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Size as assessed by CCAM volume ratio (CVR)
also correlated strongly with poor outcome
 >2.0 CVR with poor outcome
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Fetal hydrops
Severe lesion with anticipated respiratory
distress at birth
Symptomatic – either as neonate or child
Risk of malignancy
Risk of infection(s)
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Fetal thoracentesis
Thoracoamniotic shunts
Open fetal surgery
Ex Utero Intrapartum Therapy Procedure
Thoracotomy resection
VATS resection
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Thoracentesis alone is usually ineffective
Used as a temporizing measure before shunting
or resection
Thoracomaniotic shunt placement for large
predominant cyst
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Isoflurane for uterine relaxation and anesthesia
Low transverse maternal laparotomy
Sterile intraoperative US
Hysterotomy and uterine stapler
Fetal chest entered at 5th intercostal space
thoracotomy
Subsequent delivery via C-section
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Principles to improve outcome
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Fetal intravenous access prior to thoracotomy
Fetal blood gas, Hct
Pretreat with atropine and fluid volume
Fetal echocardiography to monitor fetal myocardial
performance
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Uses placental bypass
during the fetal
thoracotomy
Only fetal head, neck
and chest are delivered
Continuous
amnioinfusion
Uterine relaxation
maintained
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In setting of maternal transport, planned
delivery, facility with neonatal intensive care and
ECMO capability
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Treatment recommend with asymptomatic
patients for subsequent infection and
malignancy risk
Operative intervention ideally after 4 weeks to
reduce anesthetic risk
Before 10 months
Thoracoscopic resection – reduced hospital stay,
limited by lesion size and visibility
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Fetal death caused by hydrops, fetal surgery,
prematurity, or other malformations
Respiratory distress due to above, pulmonary
hypoplasia, pulmonary hypertension
Post-natal death
Pneumothorax, hydrothorax
Malignant change: rhabdomyosarcoma, pulmonary
blastoma, squamous cell carcinoma,
bronchiolalveolar
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Five Types of CPAMs – prognosis depends on type,
microcystic worse prognosis
 Type 0: not compatible with survival
 Type 1: surgical excision in neonatal period is curative and
prognosis excellent
 Type 2: Depends on severity of accompanying anomalies
 Type 3: lesions frequently have severe pulmonary
hypoplasia and pulmonary HTN
 Type 4: Good with surgical resection
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Risk of hydrops is high
Prenatal diagnosis and monitoring improves
intervention options and treatment planning
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Adzick NS, et al: Fetal cystic adenomatoid malformation: Prenatal diagnosis and natural
history.Journal of Pediatric Surgery 20:483, 1985.
Cha I, et al: Fetal congenital cystic adenomatoid malformations of the lung: A
of Pediatric Surgery 37: 331-338, 2002.
Keswani SG, Crombleholme TM, Rychik J, et al: Impact of continuous intraoperative
monitoring on outcome of open fetal surgery.Fetal Diag Ther (in press).
MacGillivray TE, et al: Disappearing fetal lung lesions.Journal of Pediatric Surgery 28:1321,
1993.
Mashiach R, et al: Antenatal ultrasound diagnosis of congenital cystic adenomatoid
malformation of the lung: Spontaneous resolution in utero.J Clin Ultrasound 21:453, 1993.
McCullagh M, et al: Accuracy of prenatal diagnosis of congenital cystic adenomatoid
malformation.Arch Dis Child 71:F111, 1994.
Moran L, et al: Prenatal diagnosis and management of fetal thoracic lesions.Semin
Perinatol 18:228, 1994.
Stocker JT, et al: Congenital cystic adenomatoid malformation of the lung: Classification
and morphologic spectrum.Hum Pathol 8:155, 1977.
Tsao KJ, Hawgood S, Vu L, et al: Resolution of hydrops fetalis in congenital cystic
adenomatoid malformation after prenatal steroids therapy.Journal of Pediatric Surgery (in
press).