The Full Story on CPAMs

Here we cover Congenital Pulmonary Airway Malformations (CPAMs) through a story with the help of Dr. Todd Ponsky, Dr. Pam Choi, Dr. Beth Rymeski, Dr. Jacob Langer, and Dr. Steven Rothenberg. 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