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Archives This article meets the criteriafor 1.0 credit hour in Category I of theAMA Physician’s Recognition To obtain

Congenital Malformatio& Melissa

Award. credit,

the

questionnaire

the

end oftbe

of the

J.

see

Cystic

Adenomatoid

L. Rosado-de-Christenson, Stocker, COL, MC,

Thomas

AFIP

Maf,

USAF,

MC

USA

at article.

.

Congenital cystic typically manifests

adenomatoid

expansion

affected

of the

based are

on

the

size type

(not exceeding cysts. Radiologic small

cysts

choice sence

cysts

by large

distinct

the

typically

findings

contain

single

and

solid-appearing

is excision

of the affected

of pulmonary

hypoplasia,

have

lobe.

Type

of a more

hydrops,

or

I lesions

than

uniform

contain

large

2 cm size

microscopic

cysts,

masses.

that

described

more

III lesions

The

The prognosis

fetal

been

(measuring

or multiple

lesion

to progressive

appearance. cysts

type

include size,

types sizes

and

is a rare

secondary

microscopic

ofvarying

in diameter),

of uniform

distress

Three and

cysts

II lesions

2 cm

of the lung

respiratory

lung.

of the

characterized

in diameter),

:

malformation

as neonatal

multiple

treatment

is favorable associated

of

in the

ab-

congenital

anomalies. INTRODUCTION

U

Cystic

adenomatoid

malformation,

a congenital

hamartomatous

lesion

of the

lung,

accounts for approximately 25% ofcongenital lung lesions. It usually involves one lobe or part ofa lobe, but multiple lobe involvement has been reported (1). The lesion affects male subjects slightly more frequently than female subjects and has no racial predilection. The vast majority of patients present in the immediate neonatal period, but antenatal diagnosis is possible and late presentation in olden children and adults occurs (2). The term congenital adenomatoid malformation of the lung was first used by Ch’in and Tang in 1949 (3). They reported one case and reviewed 10 previously reported cases in which a solid-appearing lung mass consisting of an adenomatoid on glandhike proliferation of terminal respiratory structures occurred

Abbreviation: Index

H.E

terms:

RadloGraphics I

,

From

thology, Nuclear

the

hematoxylin-eosin

Infants,

newborn,

1991;

11:865-886

Departments

respiratory

of Radiologic

Pathology

Bldg 54, Km M121, Masks and Medicine (M.L.R.) and Pathology

Received

May

3, 1991;

revision

system,

(M.L.R.)

Fern Sts, (J.T.S.),

requestedjune

#{149} Lung,

60. 146

and

Pediatric

Washington, Uniformed 7 and

cysts,

60. 146

Pathology

DC 20306-6000; Services University

receivedJuly

#{149} Lung,

(J.T.S.), and the ofthe

1; acceptedJuly

diseases,

Armed

60.146

Forces

Institute

of Pa.

Departments ofRdiology Health Sciences, Bethesda,

1. Address

reprint

requests

and Md. to

M.L.R. The

opinions

or as reflecting

or assertions the

views

contained of the

herein

Department

are

the

of the

private

views

of the

Air Force,

the

Department

authors

and

are

of the Army,

not

to be construed

or the

Department

as official of De.

fense. C

RSNA,

1991

865

Figure 1. (Reprinted,

able

sizes

sembling

ofthe three types ofcongenital cystic adenomatoid malformation. with permission, from reference 10.) (a) Type I lesions have large cysts of van(2-10 cm). Dominant cysts may occur. (b) Type II lesions have smaller cysts reDiagram

back-to-back

bronchioles.

Type III lesions have numerous tered, thin-walled bronchiohehike (C)

in stillborn

drops solid tic

(3). mass,

areas

or

premature

Since many have

neonates

with

the initial description cases with macroscopic

also

been

reported,

and

on

radiologic-pathohogic

a classi-

ra-

correla-

common clinical presentation is acute progressive respiratory distress occurring shortly after birth with cyanosis, grunting, retrac-

(8).

tachypnea.

At physical

Large

RadioGrapbic.s

lesions

may

compromise

Rosado-de-Christenson

hung.

secondary

to cystic adenoma-

have

been

proposed,

includ-

may present in early infancy with 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 (9). In the latter cases, it can be difficult to determine whether the infection began in a congenital malformation or in norma!

lung,

since

inflammation,

abscess

formation, and fibrosis can result in the formation ofepithelial-hined pulmonary cysts. Some of these cases may represent cystic adenomatoid malformation (2). Rarely, patients come to medical attention because of chest

normal

of the fetal lung, resulting in hypoplasia and stillbirth or neonaCystic adenomatoid malformation is

U

normal

along with scatan entire lobe.

Patients symptoms

examination,

the

adjacent

ing impaired fetal swallowing due to mass effect on the esophagus, increased fluid production or decreased fluid absorption by the lesion, and secretion of antidiuretic hormone

there may be decreased breath sounds, distant and shifted cardiac sounds, hyperresonance on the affected side, and prominence of the ipsilateral chest. Enlarging lesions may cause progressive symptoms due to expansion and compression of the adjacent normal lung and mediastinum (4). development pulmonary tal death.

the

toid malformation is impaired cardiac contractiity and impaired venous return to the heart due to compression of the heart and inferior vena cava by the lesion (4-6). Cystic adenomatoid malformation may manifest antenatally as a uterus too large for dates secondary to polyhydramnios (6,7). Several mechanisms for its development

and

with

of fetal hydrops ma!-

U CLINICAL PRESENTATION The majority of cases of congenital cystic adenomatoid malformation are manifested in the immediate neonatal period and affect both premature and full-term infants. The most

tions,

U

blends

(adenomatoid) structures The lesion tends to involve

of the recognized causes of nonimmune hydrops (defined as severe generalized edema or anasarca not associated with incompatibility in blood group type) (5). The proposed mechanism for the development

tion.

866

lesion

one fetal fetal

hy-

of a cys-

fication scheme has been developed. In this report, we review the microscopic and gross features of cystic adenomatoid formation, as well as its clinical manifestations, therapy, and prognosis. The varied diologic appearances are illustrated with emphasis

The

glandhike structures.

and

Stocker

Volume

11

Number

5

a.

b. 2. Type I, microscopic appearance. (a) The wall of the large cyst is lined by ciliated pseudostratified columnar epithehium (“respiratory” epithelium). Note discrete fibromuscuhar wall (arrow) beneath the undulating epithelium. (Oniginal magnification, x60; hematoxyhin-eosin [H-El stain.) (b) Cysts (C) lined with cuboidal to columFigure

nar epithelium are separated by dilated bronchiolehike and alveolar-duct-like structures. (Original magnification, x 100; H-E stain.) (c) Clusters of

mucogenic

occupy cyst. The apparent (bottom) with nal magnification, x 120;

lining

cells

of a large

a portion of the epithehial apical mucin is readily an alcian blue stain. (OrigiH-E

and

alcian

blue

stains).

C.

pain

or

mality

the on

incidental

detection

a radiograph

in the

of an absence

abnorof

(9).

symptoms

epithehium) and often display a papillary or pohypoid appearance because of the presence of elastic tissue beneath the epithehium (Fig 2a). In addition to elastic tissue, the cyst wall contains thin to broad bands of smooth musdc and fibrovascular connective tissue. Cartilage plates may be present in the connective tissue

U HISTOLOGIC Although cyst size cally

and

grossly

adenomatoid scopic

to classify

findings

based

are

Stocker of cystic on

gross

also

cysts

radiographi-

congenital

malformations,

of the types. three types tion

FEATURES is used both

associated

and colleagues adenomatoid and

cystic

specific

microwith

each

described malforma-

microscopic

features

(Fig 1) (10).

Type I cystic adenomatoid malformation, large-cyst type, contains one or more cysts varying from 2 to 10 cm in diameter, sunrounded by multiple smaller cysts. The larger the

cysts

are

lined

columnar

September

1991

with

ciliated

epithehium

(ie,

of some

of the

resemble

larger

dilated

cysts.

bronchioles

The and

smaller are

lined by cuboidal to columnar epithelium overlying a thin fibromuscular wall. Alveolar ducts, alveolar saccules, and alveoli are interspersed among the cysts (Fig 2b). A unique finding of the type I lesion is the presence of clusters of mucogenic cells amid the lining of the large cysts or within alveoli adjacent to the cysts. These mucous-producing cells are noted in at least one-third of type I lesions and rarely may be a dominant feature (Fig 2c).

pseudostratified

typical

“respiratory”

Rosado-de-Christenson

and

Stocker

U

RadioGraphics

U

867

a.

b.

3- Type II, microscopic appearance. (a) Back-to-back bronchiolehike structures (top) merge with normal pulmonary parenchyma (bottorn). Note partially entrapped normal cartilage containing bronchus (b) at the lower right. (Original magnification, x 25; H-E stain.) (b) Bronchiolelike structures are lined by cuboidal to columnar Figure

epithehium. (Original magnification, x60; stain.) (c) A subset of cystic adenomatoid

mation type II contains striated muscle (rhabdomyomatous dysplasia) scattered out the lesions. (Original magnification,

H-E

malforfibers throughX200; H-E

stain.)

The type II lesion, the intermediate cyst type, contains cysts that are more simple and rarely exceed 2 cm in diameter. The cysts, lined by cuboida! to columnar epithelium, resemble dilated terminal and respiratory bronchioles organized in a back-to-back configuration. The larger cysts have only a thin fibromuscular wall, and the smaller ones are devoid of muscle fibers. Cartilage plates are rarely present except for those that are part of normal bronchi near the edge of the lesion (Fig 3a, 3b). The bronchiolar structures are mixed with dilated alveolar ducts, alveolar saccules, and alveoli. Mucogenic cells are not seen in the type II lesion.

868

U

Ra4ioGrapbics

U

Rosado-de-Christenson

C.

A subset of type II cystic adenomatoid ma!formation contains, in addition to the bronchiolelike structures, strands of skeletal musdc fibers. These fibers may be found adjacent to the cysts, around blood vessels, or within

the connective

tissue

between

alveolar

ducts

and

alveoli (Fig 3c). Type II lesions may be associated with other severe malformations (eg, renal agenesis or dysgenesis). In addition, within 15%25% ofextralobar pulmonary sequestrations, focal areas with microscopic features of cystic adenomatoid malformation type II can be found. The latter association is seen only with

and

Stocker

Volume

11

Number

5

.,

-

;

,

b

‘

.:

.:

..

.

.

,

:

-

lb

J

-.

#{149}-

...

lt*

a.

b.

Figure 4. Type III, microscopic appearance. tures (b) lined by simple cuboidal epithelium saccules, and alveoli. (Original magnification, blood vessels are lined by flattened to low stain.)

(a) Randomly distributed, thin-walled bronchiolelike strucare separated by structures resembling alveolar ducts, alveolar x 15; H-E stain.) (b) All components ofthe lesion except the cuboidal epithehial cells. (Original magnification, x 160; H-E

the type bryologic remains

II lesion. This suggests an early eminsult, but the nature of this finding unknown (11,12). Type III cystic adenomatoid malformation, the small-cyst type, probably represents the original adenomatoid malformation described by Ch’in and Tang in 1949 (3). This large, bulky lesion is seen primarily in newborn or stillborn male infants whose gestation was associated with significant polyhydnamnios. The lesion usually involves an entire lobe and occasionally the entire lung. The cysts infrequently exceed 0.3-0.5 cm in diameter and are randomly distributed throughout the Icsion.

Rarely,

in an

infant

portion

of0.5-1.5

cm

a smaller

of a lobe).

lesion inc

a cyst with

as a result

This

cyst

may

be

lesion

(eg,

may

expand

the

during

fibrosis,

When

cysts they

are represent

grossly

visible bronchiolehike

cysts

a

extrauter-

in type

III struc-

tunes lined by simple cuboidal epithehium overlying a very thin fibromuscular wall. The adjacent alveolarhike structures are uniformly lined by a low to flattened cuboidal epithehum

imparting

an

adenomatoid

1991

of cystic

is precluded

adenoma-

in infants

and

repair

can

produce

cysts

over

be-

within

that

have

become

inflamed

are

com-

posed of fibrovascular connective tissue infiltrated by lymphocytes, neutnophils, plasma cells, and macrophages. Lymphoid aggregates and lymphoid follicles may also be present. The presence of a fibromuscular wall and cantilage plates in the inflamed cyst wall may suggest the presence of an underlying cystic adenomatoid malformation, but caution should be employed in making a definitive diagnosis of cystic adenomatoid malformation in these cases (12).

or glandhike

appearance to the lesion. The type III lesion the only one of these types to display a truly adenomatoid component (Fig 4). Cartilage plates and mucogenic cells are absent.

September

diagnosis

the pulmonary parenchyma. These cysts may be lined by cuboidal to ciliated pseudostratifled columnar epithelium resembling the epithelial lining of the cysts of cystic adenomatoid malformation. The walls of inflammatory cysts and cystic adenomatoid malformation

respiration.

lesions,

definitive

malformation

2 or 3 weeks of age with a lesion that has come infected. In a normal lung, inflammation with subsequent necrosis, resolution,

seen

overall

of air-filling

The toid

is

Rosado-de-Christenson

and

Stocker

U

RadioGraphics

U

869

;

‘

.

.

.:-

L.

Figures

5, 6. (5) Type I, gross appearance. (a) The surface of the right-lower-lobe specimen has a central, focal area of masshike expansion. (b) Cut specimen

of the right

communicating cyst is responsible surface. Smaller

lower

lobe

shows

multiple

inter-

cysts ofvariable size. A dominant for the focal bulge on the lung cysts are present in the periphery cyst. (6) Type II, gross appearance.

of

the dominant Cut specimen of the right middle lobe shows multipie small cysts. The largest cyst does not exceed 2 cm.

U GROSS PATHOLOGIC FEATURES The macroscopic findings of cystic adenomatoid malformation are variable. The lesions may be cystic or solid and are usually confined to one lobe. Rarely, multiple lobes are affected (1). Affected areas are usually enlarged and heavy. The lesion communicates with the tracheobronchial tree (13). The aterial blood supply is via the pulmonary cinculation,

which

although

the

cases

lesion

has

have

been

a systemic

reported

blood

ing cysts pleural

870

U

RadioGrapbic.s

have the appearance or portion of a lobe. by different-sized

U

Rosado-de-Christenson

areas

degrees may

ofexpansion. be

Sub-

appreciable

at cx-

(Fig 5a) (13). The cut reveals multiple cysts of variable size, with some cysts larger than 2 cm in diameter. Although multiple cysts are always present, one cyst may be dominant in size and may have smaller cysts in its periphery (15). Thin glistening membranes line the cysts (Fig 5b). Thick-appearing walls may result from adjacent uninvolved atelectatic lung parenchyma on from collapsed surrounding cysts. The cysts may contain air, fluid, on both (10). ternal

examination

surface

in

supply

(14). Type I lesions expanded lobe may be deformed

in various cystic

of an The lobe underly-

and

Stocker

Volume

11

Number

5

8a Figures

8b. 7, 8.

Type III, gross appearance. (a) Specimen ofthe external surface ofthe left lower lobe shows a masslike focal expansion of the central portion. (b) Cut specimen of the left lower lobe reveals a predominantly solid lesion. Very small cysts (no larger than 0.5 cm in diameter) are scattered throughout the lesion. (8) Type I. (a) Autopsy specimen ofa large cystic adenomatoid malformation ofthe left lower lobe. This lesion occupied the entire left hemithorax. Pulmonary hypoplasia of the left upper lobe (obscured by the large malformation) and the right lung (arrows) is also present. (b) Cut specimens of the left lower lobe show many cysts ofvarying sizes. A dominant central cyst is present in the specimen on the right.

Type

pie

(7)

II lesions

small

are

uniform

cm in diameter

(Fig

portions

lesion

of the

have hal-lined

alveolarhike

structures

separated

September

that

structures

1991

that

by multi-

do not

6). The

exceed

(0.3-0.5

2

with

the

Large adjacent

press

Type III lesions representing epithe-

This

(“adenomatoid”) by dilated may

be

large

cm)

bronchiole-

to be

visible

at gross

inspection

(10).

(Fig7)

cyst-containing

blend

hung parenchyma. a solid appearance

normal

like

characterized

cysts

the

lesions

of all three

adjacent

compression

types

pulmonary may

may

com-

parenchyma.

interfere

with

the

in

utero development of the adjacent uninvolved hung, resulting in unilateral or bilatera! pulmonary hypoplasia (Fig 8) (6).

enough

Rosado-de-Christenson

and

Stocker

U

RadioGraphics

U

871

b.

C.

Type I. (a) Obstetric sonogram obtained at 29 weeks gestation for the evaluation ofa uterus too large for dates. Transverse image through the upper abdomen of the fetus demonstrates polyhydramnios (p), fetal ascites (a), and a large cystic mass (m) ofthe left hemithorax inverting the diaphragm and protrudFigure

9.

ing into the abdomen. consistent with fetal sion; and mediastinal

left thorax shows seen surrounding

872

U

RadioGrapbics

(b) Frontal chest radiograph of the infant at birth shows generalized soft-tissue hydrops; a large air-filled, muhticystic mass of the heft hemithorax; diaphragmatic shift (note position of the umbilical venous catheter). (c) Postnatal sonogram

a complex the larger

U

fluid-filled cysts.

Rosado-de-Christenson

mass

with

irregular

and

echogenic

Stocker

borders.

Smaller

fluid-filled

Volume

edema inver-

of the areas are

11

Number

5

a.

b. 10. Type I. (a) Obstetric sonogram obtained at 20 weeks gestation. Longitudinal image ofthe fetal thorax shows a single large cystic area in the right hemithorax. The liver (1) is visualized below the diaphragm. An additional small cyst is seen adjacent to the dominant cyst (arrowhead). (b) Frontal chest radiograph of the asymptomatic male infant at birth shows an air-filled cystic lesion of the right lung. The dominant air-filled cyst is surrounded by peripheral radiopacity that gives the appearance of a thickened wall and that may represent retained fluid or collapsed adjacent cysts. Figure

U

IMAGING

. Antenatal Obstetric modality congenital nation of nomatoid

DIAGNOSIS

Sonographic Findings sonography is a well-established for the antenatal detection of fetal anomalies. Ultrasound (US) examifetuses with congenital cystic ademalformation may reveal polyhy-

dnamnios during a routine examination for pregnancy dating on during the evaluation of a uterus too large for dates. In addition, sonography can depict findings consistent with the diagnosis of fetal hydrops, including polyhydramnios, fetal ascites, fetal anasarca, and placental edema. The detection of hydrops or polyhydramnios usually results in a search for congenital anomalies (6). The preceding findings seen in association with a solid on cystic mass of the fetal thorax should suggest the diagnosis of congenital cystic adenomatoid malformation of the lung (Fig

9a,

9b).

considered

September

The

when

1991

diagnosis

an isolated

should

cystic

also

be

on solid-

Rosado-de-Christenson

appearing thoracic mass is identified. Type I lesions may exhibit single, multiseptated, or multiple cysts (Figs 10-12). Type II lesions may demonstrate multiple cysts of uniform size. A complex appearance, with echogenic areas and multiple small cysts of uniform size,

has been

reported

(16). The microscopic

cysts

III lesions result in a solid, usually bulIry, echogenic lesion of the fetal thorax (Fig 13a). The echogenicity and solid appearance result from the multiple interfaces encountered by the ultrasound beam as it traverses the many walls of these microscopic cysts (18). The mediastinal structures may be shifted, as these lesions tend to be large (6,18). Serial examinations are useful in the follow-up offetuses with fetal hydrops. Improvement of the fetal hydrops and resolution of the polyhydramnios have been reported (1,19). A decrease in the size ofthe mass has also been reported (16). Prenatal identification of bilateral thoracic masses has rarely oftype

and

Stocker

U

RadioGraphics

U

873

C.

Figure

the fetal tions stetnic

11. Type I. (a) Obstetric sonogram. left hemithorax shows a large cystic

(open arrows). Smaller sonogram. Transverse

the large

cystic

displaces tion was

the heart performed

lesion

(straight

cysts are also image through

arrow)

Oblique image through mass with internal septaseen (solid the fetal

arrow). thorax

(b) shows

of the left hemithorax,

(curved arrow) across at 36 weeks gestation

Ob-

which

the midline. A cesarean secbecause of abruptio pla-

centae. The female newborn had respiratory distress at birth. At surgery, a cystic adenomatoid malformation of the left upper lobe was found. (c) Specimens of the cut and external surfaces of the left upper lobe show multiple cysts ofvaiable sizes. The walls of the cysts correspond to the multiseptated appearance seen at sonography.

874

U

RadioGraphics

U

Rosado-de-Christenson

and

Stocker

Volume

11

Number

5

a.

b. Figure 12. Type tamed for evaluation Longitudinal scan

rax shows

multiple

I. (a) Obstetric

sonogram oblarge for dates. the fetal right hemithospaces. (b) Obstetric

of a uterus

through cystic

too

sonogram. Transverse scan through the fetal thorax again shows the multiple cystic spaces that produce mass effect on the fetal heart (arrow). Polyhydramnios was present. Mild respiratory distress was

noted at birth. At surgery, the right lower lobe was involved. (C) Cut specimen of the right lower lobe shows multiple rounded cystic cavities, corresponding to the phy.

multicystic

appearance

seen

at sonogra-

C-

September

1991

Rosado-de-Christenson

and

Stocker

U

RadioGraphics

U

875

endotracheal and nasogastnic tubes) and the left hemidiaphragm. The mass is predominantly opaque, and mottled air-filled areas throughout it represent air in small cystic areas within the lesion. At surgery, the left lower lobe was involved. The gross appearance of this lesion is shown in Figure 7. (Reprinted, with permission, from reference 17.)

been reported of polyhydramnios

genital

differential diagnosis on without an associated mass in the fetal thorax includes other congenital lesions. Visualization of the fetal bowel in a normal location excludes a con-

876

U

RadioGraphics

(1).

U

The with

Rosado-de-Christenson

b.

diaphragmatic

hernia.

Bronchogenic

cysts

may rarely manifest as cystic lung parenchymal masses in utero. Pulmonary sequestration may manifest as a solid echogenic mass of the fetal thorax and could have a sonographic appearance similar to that of type III cystic adenomatoid malformation (1,6).

and

Stocker

Volume

11

Number

5

a. Figure newborn.

14.

Type I lesion (a) Frontal chest

in an asymptomatic radiograph obtained

male for

evaluation of right-sided cardiac sounds shows multipIe air-filled cysts occupying the left hemithora.x. The cyst walls are thin. There is marked mass effect on the mediastinum, with displacement to the right. (b) Axial

computed

tomographic

(CT)

shows multiple thin-walled, sizes in the left lung. The on the mediastinum.

image

of the thorax

air-filled cysts lesion produces

of variable mass effect

Obstetric sonography is, therefore, useful in the early diagnosis of these lesions and in the follow-up evaluation of affected fetuses. The extent of involvement can be evaluated, and additional

tected

congenital

findings intervention tion

after

of candidates

intervention

September

anomalies

may

by means of prenatal can help in planning

be

de-

US. Sonographic prompt surgical

birth

and

for

intrauterine

may

allow

aged. The clinical manifestations of the disease and the age at presentation will also influence the radiographic appearance. Type I lesions are the most common and the most common type imaged radiographically (2,2 1). Affected patients usually present in the immediate postnatal period. Chest radiographs typically show a unilateral, airfilled, multicystic lesion in the thorax of a neonate with progressive respiratory distress. The lesions may be very large and may occupy the entire hemithonax, producing mediastinal shift and mass effect on the ipsilateral hemidiaphragm (Fig 14). The abnormally expanded lung may be herniated across the midline. The uninvolved ipsilateral and contralateral portions poplastic

of the lung may be atelectatic on hydue to compression (21). Smaller

selec-

surgical

(1,20).

1991

Rosado-de-Christenson

and

Stocker

U

RadioGraphics

U

877

16a. Figures 15, 16. chest radiograph

low-up eral

frontal

(15) chest

rounded,

Type I lesion in a female newborn with a focal, small, round, partially air-filled

shows

radiograph

air-filled,

obtained

cystic

areas

at 4 months

with

thin

walls

mild respiratory lesion in the

of age shows are

seen

within

interval the

right

distress lung

at birth. (arrow).

enlargement

lesion.

(a) Frontal (b) Foh-

of the lesion.

At surgery,

the

right

5ev-

middle

lobe was resected. The cystic lesion was found in the central portion of the lobe. (16) Type I lesion in a 5-month-old male infant with mild respiratory distress since the age of 2 months. (a) Frontal chest radiograph shows a multicystic lesion in the left lung with mass effect on the mediastinum and compression of the ipsilateral upper lung. There is one large dominant cyst with multiple smaller peripheral cysts. (b) Follow-up frontal chest radiograph obtained 2 months later shows interval expansion of the lesion with increasing mass effect. The lesion now occupies the entire left hemithorax. At surgery, the left lower lobe was involved.

focal lesions without significant mass effect may also be present (Fig 15). Multiple, rounded, air-filled, thin-walled cysts of vanable size are characteristic. A single dominant cyst may be present and may be surrounded

are collapsed or fluid filled, the radiographic appearance may be one of a cystic mass with thickened walls (Figs lOb, 17a) (22,23). A homogeneous opaque lung lesion or an area of consolidation may initially be seen because

by smaller

ofretained

cysts

(Fig

16)

or

by homogeneous

solid-appearing areas that represent tatic or hypoplastic lung, collapsed cysts, or fluid-filled cysts. Progressive sion

of the

air-filled

be associated

with

distress

15,

(Figs

cysts

may

progressive 16).

When

occur

atelecadjacent expanand of the

(Fig

cysts

eas

878

U

RadioGraphics

U

Rosado-de-Christenson

in the

17b).

Communication

cysts

(Fig

levels images with

18).

When

can be identiare obtained the

tracheo-

bronchial tree allows air entering the lesion to replace the exiting fluid, with a resultant complex radiographic appearance consisting of a mixture of air-filled cysts and radiopaque a-

can

respiratory some

fluid

fluid is present, air-fluid fled if horizontal-beam

and

(Fig

Stocker

18)

(22-24).

Volume

11

Number

5

17a.

17b.

18a

18b.

Figures radiograph

17,

18. shows

(17) Type I lesion in a male newborn a large, partially air-filled cystic lesion

the mediastinum and ipsilateral hemidiaphragm. The inferior portion of the lesion is radiopaque, cyst

is seen

centrally

in the

right

hemithorax.

with tachypnea 1 hour of the right hemithorax

Thick-appearing and its infeniorly The

bowel

gas

pattern

after birth. (a) Frontal chest with marked mass effect on

walls separate convex border is normal.

some of the air-filled cysts. is visualized. A dominant (b)

Cross-table

lateral

view

of

the chest shows that the lesion is partially fluid filled. Several air-fluid levels within cysts ofvarying sizes are noted. At surgery, the right middle lobe was involved. (18) Type h lesion in a premature male newborn with severe progressive respiratory distress at birth. (a) Frontal chest radiograph shows consolidation of the left lung with air bronchograms and mass effect on the mediastinum. A small rounded, radiolucent area (arrow) is noted within the consolidated left pneumothorax. Multiple The patient died 2 days after lobe was found.

September

1991

left lung just rounded, air-filled birth. At autopsy,

above the diaphragm. (b) Follow-up cysts are noted within the previously a cystic adenomatoid malformation

Rosado-de-Christenson

and

Stocker

chest radiograph shows radiopaque left lung. involving the left lower

U

RadioGraphics

a

U

879

9 *..

19b.

19a.

20a.

20b.

Figures

pnea

19,

20.

since

herniation

(19)

Type

the age of 3 weeks. across

the

midline

II lesion

in a 7-month-old

(a) Frontal and

mass

chest effect

female

radiograph on

the

infant

shows

mediastinum.

the middle portion of the right lung. (b) Axial CT image of the chest walled cysts of the right lung. There is mass effect on the mediastinum

880

U

contralateral Type II lesion

lung. At surgery, a cystic adenomatoid in a female newborn with respiratory

graph shows small, round, ium swallow die lobe was

consolidation radiolucent examination involved.

RadioGraphics

U

malformation distress several

with

marked Small

episodes

ofcough,

expansion air-filled

fever,

of the right cystic

areas

are

and

lung

tachy-

with

present

in

shows multiple uniform, small, thinand compressive atelectasis of the of the right upper hours after birth.

lobe was found. (20) (a) Frontal chest radio-

of the right lung with air bronchograms and mass effect on the mediastinum. A area is seen over the seventh posterior rib interspace. (b) Lateral view from a barshows small, rounded, radiolucent areas over the heart. At surgery, the right mid-

Rosado-de-Christenson

and

Stocker

Volume

11

Number

5

a.

b.

Figure

2 1

Type HI lesion chest radiograph

distress on the 1st day of life. with mass effect on the mediastinum. (Reprinted, with permission, from reference 25.) (b) Thoracic sonogram shows an echogenic mass occupying most ofthe left hemithorax (solid arrows). The liver (open arrow) is visualized. At surgery, the lingula segment of the left upper lobe and the left lower lobe were involved. After surgery, the patient developed pulmonary hypertension and persistent fetal circulation, and she died on the 7th postoperative day. .

(a) Frontal

in a female

shows

newborn

partial

with

opacification

progressive

respiratory

of the left hemithorax

Type II lesions may appear as heterogeneous areas ofuniform small cysts (Fig 19) (1 1 ,2 1,22). We have reviewed one case of a type II lesion appearing as a predominantly radiopaque area in the thorax (Fig 20). Type III lesions are usually large and homogeneous, having the appearance of parenchyma! consolidation or a mass rather than that ofa cystic lesion (Figs 13b, 21a) (10,21) This

and initially fused with

is explained

malformation

cysts

by the

and

lesions.

the Small

gross

size

filling extrauterine nomatoid air

radiolucent

areas

of these within

differential

diagnosis

of a solid

racic mass in a neonate. The differential diagnosis

of a cystic

ticystic-appearing

thoracic

expansile

neonate includes congenital hernia, bronchogenic cyst, overinflation, and pulmonary Diaphragmatic

hernia

visualization filled bowel 17a).

September

the

Bronchogenic masses

period.

1991

cysts and

Infantile

intratho-

or muhmass

be

excluded

in a

usually rarely

lobar

manifest seen

hobar

progressive

effect.

The

ties,

which

malformation,

the

two

as in the

emphysema) lung

absence

toid

be

seen

Rarely,

and

linear

adenoma-

in distinguishing

in infantile

affected

hung

radiopaque a fluid-filled

mass

opaci-

in cystic

is helpful

lesions. the

usually

expansion

of internal

would

inflation,

can

lobar

be

over-

fluid

filled

and could be concystic adenomatoid

(types

I and

type

II) or with

III lesion.

With

the time,

the

more characteristic finding of an overexpanded, radiohucent lung can be seen as fluid exits the abnormal lung. Extralobar pulmonary sequestration is usually manifested in the neonatal period or in early infancy as a solid intrathoracic mass in a patient with respiratory distress. The radiographic appearance could mimic that of cystic adenomatoid ma!formation type III (6,21,23). In rare cases, cystic adenomatoid malformation

may

22).

In these

lateral,

by

or contrast materialthe diaphragm (Fig are

congenital

solid-appearing

diaphragmatic infantile lobar sequestration.

can

of air-filled loops below

mediastinal

neonatal

of the

appearance

radiopaque mass may result from of some of the lager cysts during respiration. Type III cystic ademalformation should be considered

otherwise

in the

microscopic

solid

(or causes

occur

loba,

multicystic,

air-filled dentally atic

after cases,

the the

1st year lesions

oflife are

(Fig

usually

uni-

or subloba radiopaque,

multicystic in the lung

individual

(Fig

and may be cystic, or mixed. Rarely, an area will be detected mciof an entirely asymptom-

23)

(26-28).

overinflation

Rosado-de-Christenson

and

Stocker

U

RadioGrapbics

U

881

b.

a. Figure

22.

Type

I lesion in a 5-year-old girl with a cough. (a) Posteroantenior chest radiograph shows increased expansion of the right lung with mass effect on the mediastinum and compression of the apical portion of the lung. (b) Lateral chest radiograph shows the overexpanded lung with thin linear opacities coursing through it. At surgery, a cystic adenomatoid malformation of the right lower lobe was found. (c) Cut specimen of the right lower lobe (chose-up view). A dominant cyst is seen superiorly; smaller cysts ofvarying sizes are seen inferior to the dominant cyst. The linear opacities seen radiographically correspond to cyst walls in the lesion.

C.

882

U

RadioGrapbics

U

Rosado-de-Christenson

and

Stocker

Volume

11

Number

5

Figure 23. Type I lesion in an asymptomatic 4-year-old boy. Chest radiographs were obtained

because

of exposure

culosis.

increased tion

to a relative

(a) Posteroanterior

expansion

across

noted

the

diograph

the heart.

Thin

hung base.

shows a radiolucent At thoracotomy,

involved. (c) Cut specimen shows multiple cystic spaces

active

tuber-

radiograph

of the right

midline.

in the right

with

chest

lung

with

shows

hernia-

linear

opacities are chest raarea projecting over the right lower lobe was

(b) Lateral

of the right

lower

ofvariable

sizes.

lobe

C-

September

1991

Rosado-de-Christenson

and

Stocker

U

RadioGraphics

U

883

Figure 24. Type I lesion in an asymptomatic female newborn. birth because a thoracic cyst was seen at obstetric sonography inferior left hemithorax with a central radiolucent area is seen.

nasogastric perior

tube.

portion

a lower

level

multicystic

(b) Axial CT image

of the

mass

and

mass

of the thorax

shows

effect

mediastinum.

on the

shows a large air-fluid level in the central portion nature of the lesion. At surgery, a large cystic mass

. Postnatal Sonographic Findings Sonography of the pediatric thorax can be useful in the evaluation oflarge peripheral thoracic masses. When cystic adenomatoid malformation

has

ance

of a large

mass

due

the

radiographic

homogeneous

to fluid

filling

appear-

opaque of the

cysts,

thoracic US can

9c)

(29).

Echogenic,

solid-appearing

racic masses may be seen III lesions (Fig 2 lb).

in patients

be

. CT Findings CT may be helpful in the diagnosis tal cystic adenomatoid malformation abhing differentiation from other affecting neonates in respiratory can depict the internal structure

884

U

RadioGraphics

U

obtained

An opaque

lesion

at

of the

effect on the mediastinum deviates the levels ofvarying lengths within the suAxial CT image of the thorax obtained at

the

lobe

may

not

be

possible

(30).

Type I and type II lesions may appear as multiple thin-walled, rounded, air-filled cystic areas in the lung. Air-fluid levels can be identifled, and occasionally, fluid-filled cysts are seen (Figs 14b, 19b, 24, 25). The presence of fluid does not necessarily denote supenimposed infection (30). To our knowledge, there have been no reports describing the CT appearance of type III lesions.

type

of congeniby enconditions distress. CT of the af-

Rosado-de-Christenson

(C)

radiograph

of the mass. These findings demonstrate of the left lower lobe was resected.

affected

tho-

with

Mass air-fluid

chest

gestation.

fected lung, such as the presence of air- or fluid-filled cysts (Fig 19b). The extent and distribution of disease can be assessed. The amount of mass effect on the uninvolved lung and mediastinum can also be evaluated. Because of the enlargement of the affected lobe and the resultant distortion of the normal anatomy, preoperative identification of the

helpful by allowing visualization of the internal structuneof the lesion. The complex internal appearance of multiple fluid-filled areas with internal septations or solid elements representing the cyst walls can be demonstrated (Fig

two

(a) Frontal

at 30 weeks

U THERAPY The definitive adenomatoid

and

Stocker

treatment malformation

of congenital is complete

Volume

cystic surgi-

11

Number

5

Figure 25. Type II lesion in an asymptomatic male newborn. Chest radiography was performed to evaluate a thoracic abnormality seen at obstetric sonography at 20 weeks gestation. The presence of a small abnormal opacity in the right lower lobe was radiographically confirmed. Axial CT image of the thorax demonstrates a small, rounded soft-tissue lesion with central air-filled cysts. At thoracotomy, wedge resection of the lesion in the right

lower

cal

excision

of the

affected

lobe

or

lobes

(31).

There have been reports of successful segmentectomy in older children with focal Icsions and in selected neonatal cases (9). The expansile character of the lesion may result in a surgical emergency because of progressive, life-threatening respiratory distress (14,31). Successful lesions

intrauterine

been cysts

has

of thoracic has

resulted

without

in the

Normal

and

definitive

tion

can

be

open fetal formation

hypoplasia is then

neonatal

surgical

surgery has also

(32).

distress

at possi-

adenomatoid

malformation

congenital of the

lung

stillborn

or

may

die

in the

Neonates

The residual postoperatively,

can

tolerate

lobectomy

1991

4.

5.

of this

lesion

may

head

respi-

interto the

6.

Congenital

cystic

a 30-year 16:704-706. Moerman

experience.

adenomatoid

P, FrynsJ,

study often cases. 106:635-640. Adzick NS, Harrison tal cystic adenomatoid

malformation:

J Pediatr

Sung

Goddeenis

Nonimmunologic

tal diagnosis

P, Lauweryns

hydrops Arch

1981;

fetalis: a Med 1982;

Pathol

Lab

MR, Ghick PL, et a!. Femalformation: prena-

and natural

history.

J Pediatr

Sung 1985; 20:483-488.

7.

lung

Rosado-de-Christenson

Rempen A, Feige A, Wunsch P. Prenatal diagnosis of bilateral cystic adenomatoid malformation ofthe lung. JCU 1987; 15:3-8. StockerJT. Congenital and developmental diseases. In: DalI DH, Hammar SP, eds. Pulmonary pathology. New York: Spninger-Verhag, 1988; 41-71. Ch’in KY, Tang MY. Congenital adenomatoid malformation of one lobe of a lung with general anasarca. Arch Pathol 1949; 48:221229. Nishibayashi SW, Andrassy RJ, Woolley MM.

JM.

well.

tissue is able to reexpand resulting in near-normal chinical function (3 1). Type II lesions may carry a poor prognosis because of associated renal and cardiac anomalies (1 1).

September

3.

immediate

neonatal period (19). In the absence of fetal hydrops, the affected patient has a good possibility of survival if the condition is diagnosed early, delivery is planned, immediate respiratory support is provided, and surgery is performed promptly (4,6).

1.

cys-

congenital anomalies. Patients with large hesions that interfere with normal pulmonary development have a poor prognosis. Severe pulmonary hypoplasia and gross fetal hydrops have a uniformly fatal outcome. Without prompt antenatal intervention, these infants be

prompt

surgical morphologic

REFERENCES

U ma!-

depends on the size of the lesion, the degree of development of the adjacent uninvolved lung, and the presence or absence of other

may

necessitate

immediate the

recognition of its varied radiologic appearances, allowing early diagnosis and optimal patient management.

2.

with

at birth

interven-

Successful

for cystic adenomatoid been reported (20).

of patients

and

support and Understanding

characteristics

hydrops

development

accomplished

U PROGNOSIS The prognosis

of fetal

of pulmonary lung

ble,

tic

resolution

drainage shunt

was performed.

U SUMMARY Congenital cystic adenomatoid malformation of the lung is a rare congenital anomaly that typically affects neonates. The condition may be detected antenatally by means of obstetric sonography and may cause severe respiratory ratory vention.

of these

reported. In utero via a thoracoamniotic

evidence

birth.

treatment

lobe

8.

Golladay S, Mollitt able fetal hydrops.

DL. Surgically J Pediatr Surg

59-62. OstorAG,

DW.

Fortune

adenomatoid Clin

Congenital

malformation

Pathol

1978;

and

ofthe

correct1984;

19: cystic AmJ

lung.

70:595-604.

Stocker

U

RadioGraphics

U

885

9.

10.

Wolf SA, HertzlerJH, Phihippart Al. Cystic adenomatoid dysplasia of the lung. J Pediatr Sung 1980; 15:925-930. StockerJT, MadewehljE, Drake RM. Congenital

11.

12.

13.

cystic

15.

18.

of

23.

thology. Philadelphia: Bale PM. Congenital

24.

lesions Tucker cystic

25.

Auringer

a form

Lippincott (in press). cystic malformation

ofcongenital

Goodman

of

RK, Sieber

WK, Yunis

of the lung: of the literature.

EJ. a report Pathoh

of 17 cases Annu

for

(RadioGraphics

1.d

886

U

RadioGrapbics

the

test

1991;

2.b

Osteoid

1 1:671-696),

3.c

U

for on

4.a

Rosado-de-Christenson

are

given

TE.

Case

Med

of the

1991;

day,

10:S 1-

Huhnick

28.

DH,

Naidich

DP,

McCauley

of congenital

DI, et al.

cystic

nomatoid malformation ofthe lung. ogy 1984; 151:569-573. Wexler HA, Dapena MV. Congenital

adenomatoid unusual

malformation: cases.

adeRadiolcystic

a report

Radiology

1978;

of three

126:737-741.

29.

Hartenberg MA, Brewer WH. Cystic adenomatoid malformation of the hung: identification by sonography. AJR 1983; 140:693694.

30.

Shacketford

31.

ofcongenital cystic adenomatoid malformations. J Comput Assist Tomogr 1989; 13:612616. WalkerJ, Cudmore RE. Respiratory problems and cystic adenomatoid malformation of lung (hener). Arch Dis Child 1990; 65:649650.

32.

Clark

GD,

SL, Vitale

Siegel

MJ.

CT appearance

DJ, Minton

SD,

Stoddard

RA,

Sabey PL. Successful fetal therapy for cystic adenomatoid malformation associated with second-trimester hydrops. AmJ Obstet Gynecol 1987; 157:294-297.

Continuing Osteoma,

ST, Sumner 1. J Ultrasound

Late presentation

1983; 90: 1065-1068. Harrison MR, Adzick NS, Jennings RW, et al. Antenatal intervention for congenital cystic adenomatoid malformation. Lancet 1990; 336:965-967.

answers

cystic

27.

1983; 11:218-221. Spontaneous resolution

Answers The

thin-walled

WesleyJR, Heidelberger KP, DiPietro MA, Cho KJ, Coran AG. Diagnosis and management ofcongenital cystic disease of the lung in children.J PediatrSurg 1986; 21:202-207.

Congenital

ofmaternal hydramnios in congenital cystic adenomatoid malformation of the lung: antenatal ultrasound features. BrJ Obstet Gynecol 20.

Multiple,

lung. AJR 1980; 135:593-604. Tr, Smith WL, SmithJA. Fluid-filled adenomatoid malformation. AJR 1977;

26.

15:387-407.

oflung. JCU BakerJL.

PC.

5104.

Fine C, Adzick NS, Doubilet PM. Decreasing size of a congenital cystic adenomatoid malformation in utero. J Ultrasound Med 1988; 7:405-408. Swischuk LE. Imaging of the newborn, infant, and young child. 3rd ed. Baltimore: Williams & Wilkins, 1988. Diwan RV, Brennan JN, Philipson EH, Jam S,

mation GlavesJ,

chini-

ofthe

number

Bellon EM. Ultrasonic prenatal diagnosis of type III congenital cystic adenomatoid mahfor19.

chest:

129:323-325.

bronchiolar

(“adenomatoid”) malformation. AmJ Clin Pathol 1979; 71:411-420. Hutchin P, Friedman PJ, Saltzstein SL. Congenital cystic adenomatoid malformation with anomalous blood supply. J Thorac Cardiovasc Surg 1971; 62:220-225.

Miller

of the pediatric

cal and pathological correlations. New York: McGraw-Hill, 1987; 41-62. MadewellJE, StockerJT, KorsowerJM. Cystic adenomatoid malformation of the lung: morphologic analysis. AJR 1975; 124:436448. GodwinJD, Webb WR, Savoca CJ, Gamsu G,

AmJ Clin Pathol 1979; 72:917-925. StockerJT. The respiratory tract. In: Stocker JT, Dehner LP, eds. Texthook of pediatric pa-

1980;

17.

ed. Radiology

MI,

22.

maLformation and review 16.

malformation

Felman AR. Abnormal bronchial, parenchyma!, and vascular development. In: Felman

the lung: classification and morphologic spectrum. Hum Pathol 1977; 8:155-171. StockerJT, Kagan-Hallet K. Extralobar pulmonary sequestration: analysis of 15 cases.

the lung:

14.

adenomatoid

21.

Medical published

Education in the July

Test 1991

issue

of RadioGraphics

below.

5.c

6.c

and

Stocker

7.b

8.a

9.a

Volume

10.c

11

Number

5