Fetal chest Flashcards
Arguments agains MR in CPAM
MR is better than US to distinguish btw BPS and CPAM, but both can cause hydrops and actual histology irrelevant if hydrops has occurred.
What is bronchopulmonary sequestration (BPS)?
A mass of nonfunctioning pulmonary tissue
Lacks an obvious connection with the tracheobronchial tree
Recieves all or most of its blood supply from anomalous systemic vessels
Is there a spectrum of BPS?
There appears to be - at one extreme, an abnl vessel supplying a nonsequestered lung, and at the other, abnl pulmonary tissue but w/o anomalous vascular supply
Can BPS and CCAM coexist in the same lesion?
Yes, it is referred to as a hybrid lesion. BPS and CCAM type II coexisting together has been reported in 25-50% of extralobar sequestration cases.
What are the forms of BPS?
2 forms:
Intralobar - more common in infants & children, accounting for 75% of cases, shares the same pleural investment with the normal lung.
Extralobar - 25% of cases in infants & children, has a separate pleura from the lung and may either be intrathoracic or subdiaphragmatic in location
Theory re: embryogenesis of BPS
A supernumerary lung bud arises caudal to the normal lung bud and migrates caudally with the esophagus. If this lung bud arises prior to pleural development, the bud becomes intralobar and is invested with adjacent lung. If arises after pleura formation, the bud will grow separately and become invested with its own pleura - extralobar BPS.
Male or female preponderance in BPS?
Male - Extralobar 3:1, intralobar 1.5:1
Which is more common in the fetus/neonate: extralobar or intralobar BPS?
Extralobar
Most common location of intralobar BPS?
Lower lobe in 98% of cases.
Most common location of extralobar BPS?
Posterior lower chest, 90% on left side.
Up to 15% of extraloabr BPS can be found either within or below diaphragm.
US findings of BPS
Solid, highly echogenic mass with a clearly defined systemic feeding vessel.
Occasionally, these vessels cannot be seen on US, making it difficult to distinguish from Type III CCAM.
Addl findings:
Pleural effusion
Mediastinal shift
Hydrops
Polyhydramnios
Can intra vs extralobar BPS be distinguished on prenatal US?
Not usually. But several cases of extralobar BPS have been dx’d bc of finding of echogenic suprarenal abdominal masses.
How can extralobar BPS cause hydrops? BPS in general?
May undergo torsion of its vascular pedicle, causing venous and lymphatic obstruction, leading to pleural effusion and hydrops due to systemic venous obstruction.
BPS can cause compression of IVC with venous obstruction and compromised cardiac output. Poly may result from esophageal obstruction or decreased swallowing.
Prognosis of BPS with hydrops
Uniformly results in fetal or neonatal death if untreated. There are anecdotal reports of cases treated in utero with thoracoamniotic shunting of the pleural effusion.
Is there an increased risk of anomalies with BPS?
Yes, especially extralobar (60%). Most common = CDH, pectus excavatum, TE fistula, esophageal duplication, and congenital heart disease.
Intralobar type has a lower incidence of associated anomalies (10%).
DDx of intrathoracic BPS
Type III CCAM
Mediastinal or thoracic teratoma
CDH
DDx of intra-abdominal extralobar BPS
Mesoblastic nephroma
Neuroblastoma
Antenatal natural history of BPS
Depends on if its intralobar or extralobar, thoracic or abdominal, presence of absence of hydrops and other associated anomalies. It was once thought that in fetuses with BPS, hydrops invariably developed, and fetus died in utero or during the neonatal period. Then 6 cases reported of BPS with contralateral mediastinal shift that dramatically decreased in size over time and spontaneously resolved. Postnatally, the lesions could only be seen on CT or MRI. There were no signs of hydrops in any of these cases. Adzick et al then reported that 75% of BPS dx’d prenatally resolve spontaneously.
Outcome of intra-abdominal extralobar BPS
Somewhat better than that for intrathoracid lesions, rarely associated with hydrops. Poly may still develop due to esophageal or gastric compression.
Management of pregnancy with BPS
Exclude CDH, mediastinal teratoma, CCAM
Eval adrenal glands & kidneys to distinguish abdominal extralobar BPS from mesoblastic nephroma & neuroblastoma
Detailed US for assoc anomalies
Fetal MRI can help with ddx and identify feeding vessel
Fetal karyotype
Fetal echo
Options for fetal intervention in BPS
If tension hydrothorax from pleural effusion, then thoracoamniotic shunting is an option
If mediastinal shift and hydrops from mass, without pleural effusion, then fetal surgery for pulmonary resection could be considered, as with CCAM.
Treatment of the newborn with BPS
If large - deliver in a setting prepared to deal with pulm hypoplasia
If small - community setting may be appropriate
Examine for associated anomalies
If intraabdominal, usually no resp compromise and can have elective resection
Common locations of feeding vessels in BPS
20% subdiaphragmatic - more common with right-sided lesions
15% more than one vessel present
Why should postnatal resection of BPS be considered
Risk of infection, hemorrage, and malignant transformation, even if asx
Recurrence risk of BPS
No known genetic predisposition
One case of recurrence in male siblings reported
What is CCAM?
Congenital cystic adenomatoid malformation (aka congenital pulmonary airway malformation)
Multicystic mass of pulmonary tissue with a proliferation of bronchial structures
Theories - may represent a failure of maturation of bronchiolar structures at 5-6w gestation, or focal pulm dysplasia, or result of airway obstruction.
Is CCAM more common in males or females?
Slightly more common in males
Is CCAM more commonly unilobar or multilobar? Unilateral or bilateral?
Unilobar in 80-95% of cases, bilateral in fewer than 2%.
Does CCAM have a communication with the tracheobronchial tree?
Yes, unlike BPS. But the connection is minute and tortuous.
Where does the blood supply come from for CCAMs?
Arterial and venous drainage comes from nl pulmonary circulation, in contrast to BPS. Anomalous A/V drainage has been reported, as well as “hybrid” CCAMs that have a systemic blood supply.
How are CCAMs classified?
Histologically, by Stocker, but it is commonly applied to US appearance.
Type 0 CCAM
Bronchial (previously described as acinar dysplasia)
Type I CCAM
Bronchial/bronchiolar
50% of cases
Usually favorable outcome
Single or multiple cysts lined by ciliated pseudostratified epithelium, usually quite large (3-10 cm) and few in number (1-4).
Type II CCAM
Bronchiolar
40% of cases
More numerous cysts of smaller diameter (<1 cm), lined by ciliated, cuboidal, or columnar epithelium
Increased assoc congenital anomalies
Type III CCAM
Bronchiolar/alveolar dust
Large homogenous microcystic masses that cause mediastinal shift
Bronchiole-like structures lined by nonciliated cuboidal epithelium
Can present with hydrops
Type IV
Peripheral
Very large cysts up to 10 cm, lined by flattended epithelium resting on loose mesenchyme
Most common type of CCAM
Type I - 50% of postnatal cases
Type II - 40%
Type III - 10%
Type IV- 15%
Type of CCAM most common associated with congenital anomalies
Type II
Most common anomalies associated with Type II CCAM
GU - renal agenesis or dysgenesis
Cardiac - ToF or truncus arteriosus
Jejunal atresia
CDH
Hydrocephalus
Skeletal anomalies
Adzick’s modification of Stocker’s CCAM classification
Macrocystic - single or multiple cysts > 5 mm in diameter
Microcystic - more solid and bulky, cysts < 5 mm in diameter, more risk for hydrops
US appearance of CCAM
Type I and II - cystic or echolucent pulmonary masses, may appear similar to CDH, cystic hygroma, bronchogenic or enteric cysts, and pericardial cysts
Type III - large hyperechogenic mass, often assoc with mediastinal shift and hydrops in advanced cases
Use color Doppler to search for a feeding vessel - usually comes off descending aorta, but transdiaphragmatic vessels have been observed
How does the appearance of Type III CCAMs change around 30 week?
May become isoechogenic with adjacent normal lung and sonographically invisible, but still apparent on MRI
DDx of CCAM
CDH (esp Type I, look for peritalsis, can use MRI, CCAM can coexist with CDH)
Bronchogenic or enteric cysts
BPS
Bronchial atresia or stenosis
Mediastinal cystic hygroma
Neuroblastoma
Brain heterotopia
Why does hydrops occur with CCAM?
Usually with large lesions, often Type III, that cause mediastinal shift and vena caval obstruction
May be exacerbated by loss of protein from the CCAM into the amniotic fluid, reducing fetal colloid oncotic pressure from hypoproteinemia.
Fetuses may survive after onset of hydrops, after CCAM growth plateaus around 26w gestation
Overall prognosis of CCAM
Depends on size, macrocystic vs microcystic
Polyhydramnios may develop due to decreased fetal swallowing
Regression more common with Type III, occurs in 6-11% of cases
Adzick et al 1998, 134 fetuses with CCAM:
In fetuses that did not develop hydrops, postnatal survival 100%
If hydrops, 100% mortality, either in utero or postnatally
Many babies with large lesions required substantial ventilatory support, 4 needed ECMO
15 appeared large at 20-26 weeks with mediastinal shift, but then clearly decreased in size
Calculating CCAM volume
Formula for volume of ellipse - h x w x l x 0.52 cm3, measure greatest length in sagittal section, width and height at 90 degrees to sagittal measurement
Calculating CCAM volume ratio
Divide CCAM volume by head circumference (in cm) to correct for GA differences.
Significance of CCAM volume & volume ratio
Higher if fetuses destined to develop hydrops. Of fetuses with CVRs > 1.6, 80% developed hydrops.
< 1.6 and no evidence of a dominant cyst, only 2% risk for hydrops
Management of pregnancy with CCAM
Detailed US, w/ color Doppler to look for systemic blood supply
Note size of cysts, size and location of CCAM
Look for mediastinal shift, hydrops
Incidence of chromosomal abnl uncertain - 1/134 in Adzick (T21)
Fetal echo - increased truncus and ToF
Fetal echo findings associated with mediastinal compression
Compression of the ventricles -> elevated central filling pressures -> altered inflow pattents -> reversal of IVC flow w/ atrial contractions —> hydrops
Fetal intervention for CCAM
If there is a dominant cyst, even is CVR < 1.6, then still significant risk of acute enlargement of cyst and hydrops. Thoracoamniotic shunt may be considered at the very earliest sign of hydrops. If CVR > 1.6, with or without dominant cyst, 80% chance of hydrops. Twice weekly US to detect earliest sign of hydrops -> shunt.
Fetuses w/ CCAM and dominant cyst with hydrops before 32w -> shunt.
If hydrops + microcystic CCAM not amenable to shunt -> in utero resection -> high resolution of hydrops but also high fetal death rate.
Maternal betamethasone should be considered in all cases with a CVR of 1.6.
When should steroids be given for CCAM?
When CVR is 1.6. May arrest growth of the solid component, but it is not proven that steroids truly affect growth of the CCAMs and this may be part of the natural history.
What is the intervention for CCAM with significant mediastinal shift and cardiac compression?
EXIT-to-resection
Treatment of the newborn with CCAM
Delivery at center with NICU bc of possible pulmonary hypoplasia
Type 1 or II may be at risk for air trapping, pneumothorax
Postnatal treatment of CCAM
Complete resection, usually by lobectomy, is treatment of choice
If regresses antenatally, CT or MRI may be necessary to detect residual tissue. Some authors argue that if they are asx, may be managed with observation.
Others argue re: risk of myxosarcoma, embryonal rhabdomyosarcoma, pleuropulmonary blastoma, and bronchoalveolar carcinoma arising in CCAMs.
Infection is another potential complication
Recurrence risk for CCAM
No known genetic defect responsible
No cases of recurrence in a sibling or offspring reported
