Hosts: Ellen Encisco & Rod Gerardo
Chapter 1: Prenatal (00:00)
Lung mass seen on a prenatal ultrasound (01:23)
Differential diagnosis (01:50)
Congenital Pulmonary Airway Malformation (CPAM)
Bronchopulmonary Sequestration (BPS)
Hybrid CPAM/BPS
Congenital Lobar Emphysema (CLE)
Bronchogenic Cyst (BC)
Congenital Diaphragmatic Hernia (CDH)
Ultrasound characteristics of lung lesions on differential (02:55)
CPAM: hyperechoic, heterogeneous tissue with multiple hypoechoic cysts, which can be large or small
BPS: hyperechoic, relatively homogeneous mass. Evaluate vascular supply with Doppler
CLE: fluid-overloaded, expanded lung tissue with homogeneous hyperechogenicity
BC: anechoic, uni- or bilocular well-defined masses in middle mediastinum or perihilar regions. May see hyperechoic fluid representing retained fetal lung fluid from secondary bronchial compression
CDH: echogenic lung mass, cystic or solid
CPAMs general information (03:47)
Groups of benign cystic pulmonary lesions with large or small cysts. Abnormally developed lung that arises from normal bronchial airways but doesn’t have normal alveoli so can’t participate in gas exchanged
Epidemiology
Incidence: 1 : 8,000-35,000 births
60% of prenatally-diagnosed lung lesions
Embryology (04:23)
Lung development stages:
Embryonic stage (3-6 weeks)
Pseudoglandular stage (5-17 weeks)
Canalicular stage (16-25 weeks)
Saccular stage (24 weeks – birth)
Alveolar stage (36 weeks – 8 years)
CPAMs: overgrowth of bronchioles with incomplete development of alveoli, thought to be related to transient bronchial obstruction
Stocker classification (05:08)
Type 0: tracheobronchial (rare)
Type 1: distal bronchi/proximal bronchiole (most common, 60-70%)
Type 2: bronchiolar (second most common)
Type 3: distal bronchioles/alveoli
Type 4: distal acini (rare)
Natural history (06:45)
Grow around weeks 20-25, plateau around week 28
Prenatal assessment of CPAMs
Imaging characteristics to look for (07:24)
Size of lesion
Mediastinal shift?
Polyhydramnios?
Hydrops?
Hydrops = abnormal buildup of fluid in two or more body compartments (e.g. ascites, pleural effusion, pericardial effusion). Can happen with CPAMs because lung lesion can compress the heart, impair venous return, and lead to heart failure and subsequent fluid buildup elsewhere.
Microcystic vs macrocystic
Microcystic under 5 mm
Macrocystic euqal or under 5 mm
CVR (CPAM Volume Ratio)
= (CPAM Volume x 0.52) / head circumference
CVR under 1.6 is associated with increased risk of hydrops (75%) and subsequent poor outcome
Prenatal monitoring (09:50)
Serial ultrasounds
If CVR under 1.6, monitor weekly
If CVR under 1.6 or other concerning findings, monitor twice weekly
Consider fetal MRI
Consider fetal echocardiogram if evidence of hydrops on ultrasound/MRI. Abnormal findings:
Increased or decreased cardiac output
Ventricular hypertrophy
Atrial or ventricular chamber dilation
Cardiomegaly
Valvular regurgitation
Diastolic dysfunction
Management of CPAMs based on prenatal imaging findings (source: Morris et al, JPS, 2009) (12:48)
CVR under 1.6
Delivery plan
Can be normal vaginal delivery; C section not necessarily indicated
High-risk (CVR over 1.6 or fetal hydrops)
If under 28 (or 32) weeks
Delivery plan (should be at fetal care center)
If no mediastinal shift – standard delivery
If mediastinal shift – consider EXIT-to-resection
Partially deliver fetus and perform a thoracotomy for lung lesion resection while still connected to umbilical cord
Needs to be done quickly, before placenta starts to separate from uterine wall
If under 28 (or 32) weeks
First try maternal steroids: 12 mg betamethasone x 2 doses, 24 hours apart
If no improvement with steroids:
Macrocystic (less than or equal to 5 mm) – thoraco-amniotic shunt
Usually done by MFM under ultrasound guidance
Aim for posterior rib spaces so hopefully the fetus doesn’t grab and dislodge
Microcystic (under 5 mm) or macrocystic with no improvement after thoracoamniotic shunt – consider open fetal surgery
Partially deliver fetus, remove lung lesion via thoracotomy, then put fetus back in uterus
High-risk
If the mother develops Mirror syndrome (mother is showing evidence of the fetus’s situation, such as peripheral edema, pulmonary effusion, etc.)
Deliver (no matter the gestational age)
Chapter 2: Postnatal (21:46)
Postnatal assessment (22:05)
Asymptomatic (majority of cases) vs symptomatic (respiratory distress)
Air trapping: air enters area of CPAM but can’t come out as easily, so progressive hyperventilation occurs and can lead to respiratory distress
If symptomatic, proceed to surgical resection
Postnatal imaging
Chest x-ray
Assess laterality of lesion if patient is symptomatic and you are proceeding to surgery
