DR. SNEHA S. VOLVOIKARMODERATORS: DR. RAGHURAM P.

DR. JAIPAL B.R .

CONGENITAL CYSTIC ADENOMATOID

MALFORMATION

Congenital pulmonary airway malformation (CPAM) spectrum

CCAM (Congenital

cystic adenomatoid malformation)

BPS (Bronchopulm

onary sequestration)

CLE (Congenital

lobar emphysema)

What is CCAM?

Rare pulmonary developmental hamartmatous abnormality

Comprised of pulmonary tissue with abnormal bronchial proliferation

The fundamental pathologic feature of the lesion is adenomatoid proliferation of bronchioles that form cysts at the expense of normal alveoli

25% of all congenital lung masses

1 in 25000 live births

>95% are limited to 1 lobe or segment

2-3% are B/L

Pathogenesis

Absence of bronchial cartilage & tubular glands

Overpdn of terminal bronchiolar structures without alveolar differentiation

Characteristics

Has a normal communication with the T-B tree

Normal vascular supply & venous drainage to pulmonary circulation UNLESS asso with sequestration (type II & III)

Lined by respiratory epithelium

Types

Type I Type II Type III

Features 2-10 cms cyst < 2 cms cysts <0.5 cm cysts

Variable sized cysts

Uniform cysts Appear solid

ciliated pseudostratifiedepithelium

ciliated cuboidal or columnar epithelium

shows adenomatoidelements consistent withdistal airway

Stage of development

Gestational age

Description Type

Embryonic 26days- 6 weeks

‘Lung bud’ derived from primitive foregut and branches dichotomously to form the early tracheobronchial tree

Pseudoglandular

6- 16 weeks

Airways develop to the level of terminal bronchioles but end blindly within primitive stroma

III

Canalicular 16-28 weeks

Multiple alveolar ducts arise from respiratory bronchioles and are lined by Type II pneumocytes

II

Saccular 28-34 weeks

Increase in number of terminal sacs, thinning of interstitium, proliferation of capillary bed

I

Alveolar 34-36 weeks

Mature alveoli are composed exclusively of alveolar lining cells, basement membrane, cap endothelium

Additional types

Type 0 Type IV

Acinar dysplasia or agenesis Large peripheral cyst of the distal acinus lined predom

with alveolar type cells

Associated with malignancy, specifically

pleuropulmonary blastoma.

CCAM

CPAM

Because only 3 out of 5 are cystic

AND

Only 1 is adenomatoid

Prenatal classification of CCAM based on USG

Macrocystic Microcystic

Single or multiple cysts >/= 5mm diameter

<5 mm diameter cysts

Seen on USG as cysts, difficult to identify normal

lung on same side

Appear as a solid hyperechogenic mass bec of

numerous acoustic interfaces

Favourable prognosis Poorer prognosis

Pre natal Post natal

Antenatal USG

MRI

CXR

CT scan (once air filled)

Post natal USG

Imaging of CCAM

Imaging – Prenatal USG

Earliest diagnosis made at 16 weeks. The diagnosis is usually made in the 2nd trimester, but sometimes in the 3rd trimester when referred for investigation of polyhydramnios.

USG: identifies the location of the lung abnormality by its

appearanceevaluate the blood supply & venous drainage by

doppler determine changes in posn of other lung lobes, med

& cardiac structures

Solid, echogenic lung massOR

Mixed solid cystic massOR

Sometimes, only a single large cyst

Color doppler- vascular flow to the lesion from a branch of the pulmonary artery.

To predict outcome

CCAM volume- The CCAM volume is estimated using the formula for a prolate ellipse 

CCAM= (Length x Height x Width  x 0.52 )

A CVR is obtained by dividing the CCAM volume (cc) by the head circumference (cm) to correct for differences in the fetal gestational age.

If the CVR is < 1.6 - favorable prognosis. The risk of developing hydrops is less than two percent in these cases. The only exceptions are malformations with a “dominant cyst.”

Dominant cysts are those that comprise greater than one-third of the entire volume of the CCAM.

These lesions can enlarge acutely, do not follow a predictable pattern of growth and hence must be followed closely.

Those congenital cystic adenomatoid malformation with a CVR > 1.6 are at high risk for the development of hydrops and fetal demise ( up to 80 percent of cases).

Such malformations should be followed with twice-weekly ultrasound scans so that fetal surgery can be undertaken at the earliest signs of hydrops.

All congenital cystic adenomatoid malformation should be followed once in 2 weeks for measurement of CAM volume and CVR until the growth of CCAM reaches a plateau.

Weekly follow up if hydrops

Longitudinal section of thorax showing a large cystic lesion

Cross-section view.The large cystic lesion is seen in the right hemithorax. The heart is compressed and deviated to the left (arrow). Skin oedema and polyhydramnios

Type 2 congenital cystic adenomatoid malformation (CCAM). A, Sagittal image of a fetus at 24 weeks with Type 2 CCAM located in the posterior chest (arrows). B, Transverse image with measurements showing the inferior extent of the lesion. The mass is multicystic and located inferior and posterior to the heart. Arrowhead indicates the stomach.

Transverse image of a fetus at20 weeks with Type 3 congenital cystic adenomatoid malformation demonstrating its position posterior and to the left of the heart. The heart is displaced to the right.

Associated findings/ Complications

Mediastinal shift

Polyhydramnios

Hydrops

Determine prognosis &

Mx

Complications

If large CCAM

Altered hemodynamics & increased CVP

Hydrops- mortality- 100% if untreated

Associated anomalies

Usually isolated and rarely associated with chromosomal defects.

Associated anomalies include Renal Cardiac (truncus arteriosus & TOF) CNS & spinal defects Abdominal wall defects. Type II CCAM is more commonly associated with other

anomalies.

Elevated alpha-feto protein has been reported with type III CCAM.

MRI

Type I & II- very high SI on T2 - equal to amniotic fluid - higher than surrounding normal

lung

Type III- moderately high SI - homogenous - as they regress- SI drops - asso with pleural effusion

Coronal T2-weighted MR image shows a well-circumscribed area of T2 hyperintensity (arrow) in the left upper lobe.Oblique coronal T2-weighted MR image shows a well-circumscribed area of low T2 signal, in a fetus with a typical, resolving CCAM.

Prognosis

If no hydrops by 26 weeks Good. Therefore, surveillance done every 2 weeks during the 2nd trimester

Unilateral type I CCAM (macrocystic lesion) in the absence of hydrops and polyhydramnios - Good prognosis

The following features are suggestive of poorer prognosis in unilateral lesions:-

large size cysts mediastinal shift fetal hydrops polyhydramnios associated anomalies

Bilateral CCAM is lethal

Type 0 CCAM is considered lethal.

Resection of Type 1 CCAM is considered to be curative and outcomes are excellent.

Outcomes for Type 2 CCAM depend largely on the presence of associated anomalies.

The risk of pulmonary hypoplasia is highest with Type 3 CCAM, given its tendency for growth and mass effect & earlier development of hydrops and polyhydramnios. Pulmonary hypoplasia cannot, at this time, be predicted antenatally.

Fate

The natural history of CCAM is near exponential growth, from 20 weeks gestation until the plateau is reached which is around 26 weeks

CCAMs tend to regress during 3rd trimester (30-40%). As they regress, they become isoechoic to lung, eventually becomes inapparent in later gestation

In half of the cases there is no change in the size of the lesion, while it may enlarge in 10% of the cases.

Antenatal management

Fetal interventions

In the presence of large unilocular cysts and hydrops, consideration can be given to drainage of the cysts by thoraco-amniotic shunting.

Multicystic or predominantly solid CCAM are not suitable for catheter decompression and require resection.  Laser ablation and injection of sclerosing agents have also been described in the treatment of microcystic CCAM, in which cysts are too small for decompression.

Fetal thoracocentesis alone is ineffective because of the rapid reaccumulation of cyst fluid.

The relief of associated polyhydramnios by serial amniocentesis has also shown to be of value

In patients with large, solid CCAM with associated hydrops, open fetal surgery is indicated.

Post natal manifestations

40% with prenatal diagnosis are symptomatic at birth-acute progressive respiratory distress occurring shortly after birth with cyanosis, grunting, retractions, and tachypnea.

Require intervention or respiratory support (ECMO) with NICU admission

Even asymptomatic masses are removed d/t 1. Risk of secondary infection2. Hemorrhage3. Carcinoma4. Prevents development of normal lung

Patients may present in early infancy with symptoms of respiratory distress, vomiting, failure to thrive, and recurrent pneumonia.

Patients may also present in childhood and adulthood with recurrent infection localized in the involved lobe

Post natal (neonatal) imaging-CXR

Type I lesions -Chest radiographs typically show a unilateral, airfilled, multicystic lesion in the thorax.

Homogeneous fluid-opacity pulmonary mass may present and evolve to demonstrate an air-filled cystic radiographic appearance.

The lesions may be very large and may occupy the entire hemithorax, producing mediastinal shift and mass effect on the ipsilateral hemidiaphragm.

The abnormally expanded lung may be herniated across the midline.

The uninvolved ipsilateral and contralateral portions of the lung may be atelectatic or hypoplastic due to compression.

Type II lesions may appear as heterogeneous areas of uniform small cysts

Type III lesions are usually large and homogeneous, having the appearance of parenchymal consolidation or a mass rather than that of a cystic lesion

Initial anteroposterior radiograph of the chest in a patient with congenital cystic adenomatoid malformation on the first day of life, with dense lungs and a suggestion that the right lung is slightly more voluminous than the left lung.

On the second day of life (same patient as in previous image), an anteroposterior radiograph shows physiologic fluid resorbed from an area of congenital cystic adenomatoid malformation and replaced with an air-containing cystic area occupying the right upper lung.

Type I lesion in an asymptomatic malenewborn. (a) Frontal chest radiograph obtained forevaluation of right-sided cardiac sounds shows multipIeair-filled cysts occupying the left hemithorax. Thecyst walls are thin. There is marked mass effect on themediastinum, with displacement to the right. (b) Axialcomputed tomographic (CT) image of the thoraxshows multiple thin-walled, air-filled cysts of variablesizes in the left lung. The lesion produces mass effecton the mediastinum

CT Scan

Areas of small cysts (< 2 cm in diameter) or multiple large cysts appearing with other abnormalities (a larger cystic area, consolidation, or low attenuation) are the most frequent findings.

Low-attenuation areas are clusters of microcysts.

Air-fluid levels can be seen in some cysts. These lesions may be predominantly type I, type II, or a combination of both.

Computed tomography scanof the neonate, performedon day of life 1. There is a 0.9x 0.9 cmmass with several cysts within the medialsegment of the right lower lobe. Nosystemic vessels can be seen supplyingthe mass. Findings are consistent with aType 2 congenital cystic adenomatoidmalformation.

CT scan of the chest demonstrating a multiseptated cystic lesion in the right upper lobe consistent with localized congenital cystic adenomatoid malformation.

Chest radiographs obtained on day 2 and 3 of life show an expanding, air-filled cystic lesion (white and yellow arrows) in the right lower lobe. The newborn also had hyaline membrane disease. A CT scan of the same child shows a cystic lesion in the right lower lobe with septations (green arrow) and an air-fluid level (blue arrow).

Post natal USG

The complex internal appearance of multiple fluid-filled areas with internal septations or solid elements representing the cyst walls can be demonstrated

Echogenic, solid-appearing thoracic masses may be seen in patients with type III lesions.

Post natal management

In the case of respiratory compromise, resection is indicated and is curative with minimally invasive surgery

Elective surgery within few months after birth

Early resection may allow for compensatory lung development in the remaining tissue

Surgical management of CCAM involves lobectomy- suggested for CCAM because of risks of incomplete resection, which occurs in 15%

In symptomatic neonates the survival following postnatal thoracotomy and lobectomy is about 90%.

D/D of echogenic lesion in fetal thoraxAbnormality Location Distinguishing

feature

CCAM U/L (2-3%- B/L) Cystic & solid

Sequestration U/L (left LL-mc) Systemic blood supply

Congenital lobar emphysema

U/L (UL- most often) Similar to microcystic CCAM; enlarged echogenic lungwith mediastinal shift, prog lung expansion, absence of internal linear opacities

Congenital diaphragmatic hernia

U/L (left side more common)

Peristalsis of bowel in chest, stomach above diaphragm, absence of part of the diaphragm

Computed tomography scan of a neonate . There is a solid soft tissue density within the left lower lobe measuring approximately 3 cm 3 2 cm. A small vessel arising from the descending aorta is seen supplying this solid mass (arrows); findings are consistent with sequestration. The baby underwent resection of the mass at 3 months of age.

D/D- Cystic lesion in fetal thorax

Abnormality B/L v/s U/L Distinguishing features

CCAM U/L (2-3% - B/L) Associated with echogenic lung mass, typically multiple cysts

CDH Typically U/L Peristalsis of bowel in chest, stomach above diaphragm(abs st bubble)

Cystic Teratoma Mass does not obey lobar boundaries; may have calcifications.

Abnormality Distinguishing feature

Neurenteric cyst Adjacent to spine

Bronchogenic cyst Typically single cyst, direct connection with upper airway

Esophageal duplication

Adjacent to esophagus

Lymphangioma Crosses anatomic boundaries

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