Lung Pathology: Embryologic Abnormalities

50 Pages·2011·11.19 MB·English

2C
Chapter
Lung Pathology:
Embryologic Abnormalities
Content and Objectives
Pulmonary Sequestration 2C-3
Chest X-ray Findings in Arteriovenous Malformation of the
Great Vein of Galen 2C-7
Situs Inversus Totalis 2C-10
Congenital Cystic Adenomatoid Malformation of the Lung 2C-14
VATER Association 2C-20
Extralobar Sequestration with Congenital Diaphragmatic Hernia:
A Complicated Case Study 2C-24
Congenital Chylothorax: A Case Study 2C-37
Continuing Nursing Education Test CNE-1
Objectives:
1. Explain how the diagnosis of pulmonary sequestration is made.
2. Discuss the types of imaging studies used to diagnose AVM of the great vein of Galen.
3. Describe how imaging studies are used to treat AVM.
4. Explain how situs inversus totalis is diagnosed.
5. Discuss the differential diagnosis of congenital cystic adenomatoid malformation. (continued)
Neonatal Radiology Basics Lung Pathology: Embryologic Abnormalities 2C-1
6. Describe the diagnosis work-up for VATER association.
7. Explain the three classifications of pulmonary sequestration.
8. Discuss the diagnostic procedures for congenital chylothorax.

2C-2 Lung Pathology: Embryologic Abnormalities Neonatal Radiology Basics
2C
Chapter
Lung Pathology:
Embryologic Abnormalities
Editor
Carol Trotter, PhD, RN, NNP-BC
Pulmonary Sequestration
pulmonary sequestrations is cited as the 1902 theory of
Eppinger and Schauenstein.4 The two postulated an accessory
T
he clinician frequently cares for infants who present foregut tracheobronchia budding distal to the normal buds,
with respiratory distress and/or abnormal chest x-ray with caudal migration giving rise to the sequestered tissue. The
findings of undetermined etiology. One of the essential com- type of sequestration, intralobar or extralobar, would depend
ponents in the process of patient evaluation is consideration on the timing of the accessory foregut budding (Figure 2C-1).
of differential diagnosis with correlation to radiologic find- Early gestational development of an accessory bud would
ings and clinical presentation. Sequestrations are estimated result in development of the anomalous tissue in the intralobar
to account for 0.15–1.7 percent of all congenital pulmonary area, with resultant intralobar sequestration. Later embryonic
malformations.1 Although rare, often asymptomatic, and fre- development would allow the separation of normal lung tissue
quently not presenting in the neonatal period, pulmonary and pleura, resulting in extralobar sequestration.6
sequestrations or bronchovascular foregut malformation Foregut connections are not present in the majority of
anomalies (with or without respiratory distress) can result in cases. Because nonpatent stalks and esophageal diverticulae
abnormal radiographic findings and should be considered in have been observed between the foregut and the sequestra-
the differential diagnosis. tion, the absence of these connections could be postulated to
be a result of an involution of the original foregut connection.6
DEFINITION Vascular supply is thought to occur from the persistence of
A pulmonary sequestration is a mass of abnormal pulmo- portions of intercommunicating capillary networks that supply
nary tissue that does not have normal bronchial communica- the early tracheal bud from the sixth aortic arch (pulmonary
tion with the tracheobronchial tree and that receives its blood artery) and the fourth arch (aorta). The anomalous lung tissue
supply from anomalous systemic arteries rather than from the and its persistent vessels descend with the celiac axis to supply
pulmonary artery. Venous drainage can be into systemic or the lung from the thoracic aorta or from the aorta below the dia-
pulmonary veins.2,3 Traditionally, a sequestration that has phragm.6 Pathologically, the sequestered lung tissue is embry-
its own separate pleural investment is called extralobar. It is onic and profusely cystic. It contains disorganized, airless alveoli,
called intralobar if it is located within the normal lung without bronchi, cartilage, and respiratory epithelium. On x-ray, seques-
a separate pleural covering. Because the lesion is so variable trations usually appear as medially located, triangular or oval-
and gastroenteric connections may exist, it has been sug- shaped lung masses. The mass may appear cystic and similar to
gested that the term bronchovascular foregut malformation be other forms of congenital cystic lung disease, such as congenital
used.4,5 However, the intra-extralobar terminology remains in adenomatoid malformation. The diagnosis is confirmed by doc-
common use and will be used in this article. umenting the anomalous blood supply through aortography,
ultrasonography, or contrast CT scanning. Other radiographic
EMBRYOLOGY findings may include pleural effusion, atelectasis of normal lung
The theory of embryogenesis that best explains the pul- tissue, or displacement of mediastinal structures due to the mass
monary, vascular, and foregut anomalies associated with effect of the sequestration.5
Neonatal Radiology Basics Lung Pathology: Embryologic Abnormalities 2C-3
FIGURE 2C-1 n Drawings illustrating successive stages in the development of the bronchi and lungs.
From: Moore KL, and Persaud TVN. 2008. Before We Are Born: Essentials of Embryology and Birth Defects, 8th ed. Philadelphia: Saunders, 203.
Reprinted by permission.
CLASSIFICATION OF SEQUESTRATIONS anomalies—such as tracheoesophageal fistula, congenital
Sequestrations have been classified as intralobar, extralobar heart disease, and diaphragmatic hernia—are more common.
(accessory lobe), or Scimitar syndrome. Differentiating char- Communications with the trachea, bronchi, stomach, and
acteristics of these three types of sequestrations are presented small bowel have been reported but are rare. Most extralobar
in Table 2C-1. sequestrations are diagnosed at an earlier age than are intralo-
Intralobar sequestration (Figure 2C-2) is anomalous lung bar sequestrations.8,9
tissue located within normal lung tissue and visceral pleura Scimitar syndrome (Figure 2C-3) is an anomaly of the
and is most commonly located in the posterior basal segments entire right lung in which the lung may have only two lobes
of the lower lobe, slightly more often on the left.7 Rarely, it and is hypoplastic. The anomalous pulmonary vein drains
can be located in upper lobes or bilaterally. It is the most into the inferior vena cava. There may be an associated dex-
common type of sequestration occurring 75 percent of the trocardia or congenital cardiac anomalies.8,10
time.7 The clinical presentation may be recurrent pneumonias
or other chronic respiratory problems, such as abscesses of the CASE STUDY
affected lobe. Therefore, intralobar sequestrations are more A full-term 3.31 kg male was delivered by cesarean section
frequently diagnosed after the neonatal period.5 Associated to a 34-year-old gravida 5, para 3, ab 1 mother. The delivery
anomalies are less frequent with intralobar than with extralo- was uncomplicated, and the infant received Apgar scores of
bar sequestrations.1 8 and 9 at one minute and five minutes. The pregnancy was
Extralobar sequestration (see Figure 2C-2) is less common complicated by iron-deficiency anemia, a urinary tract infec-
than intralobar, with a male predominance. The sequestration tion during the first trimester, and oligohydramnios during
can be located above or below the diaphragm, and, unlike the third trimester. During the pregnancy, an ultrasound of
with an intralobar sequestration, the anomalous lung tissue the fetus revealed a possible abdominal mass. Subsequent pre-
is outside the visceral pleura and receives its blood supply natal magnetic resonance imaging of the fetus confirmed the
from the aorta, usually below the diaphragm. Associated
2C-4 Lung Pathology: Embryologic Abnormalities Neonatal Radiology Basics
TABLE 2C-1 n Classification of Pulmonary Sequestrations
Extralobar (Accessory Lobe) Intralobar Scimitar
Sequestration Sequestration Syndrome
Frequency Rare; four times more common in males Six times more common than
extralobar; slight male
predominance
Age at diagnosis Approximately 60% <1 year 50% >20 years Infancy
Parenchyma Separated from remainder of lung by Two types: (1) absence of major Hypoplasia of right lung often
pleural investment bronchus; (2) bronchial tree and associated with bronchial
lung complete; sequestration of anomalies (aplasia, hypoplasia,
superfluous portion of lung stenosis)
Vascular:
Arterial From aorta—usually from below From descending aorta, above or May have hypoplastic right
diaphragm below diaphragm, as one or pulmonary artery, anomalous
several arteries, occasionally from subdiaphragmatic arterial supply
intercostal or innominate artery to right lower lobe
Venous Systemic (drainage into hemizygous, Drainage toward pulmonary veins, Anomalous pulmonary venous
azygous veins) or portal system rarely into systemic veins drainage of right lung to vena cava
(left-toright shunt) causing curved
vascular shadow in right lower
lung field
Location In left costodiaphragmatic sinus or below Two-thirds left; rare bilateral; dorsal Right lung
diaphragm segment of lower lobes; rarely
upper lobes or lingula
Diaphragmatic defect 60% Rare
Associated anomalies Frequent, including tracheoesophageal Occasional cystic change or Dextroposition of heart with or
and gastric fistulas, tracheal anomalies, sequestered portion of lung; other without congenital cardiac
ectopic gut, diaphragmatic hernia and anomalies and malformations anomalies, hemivertebrae
other diaphragmatic malformations, similar but much less frequent is associated with cases of
pericardial cysts, vertebral anomalies, than in extralobar hypoplasia or aplasia of right lung
anomalous pulmonary venous return,
congenital heart disease
Adapted from: Platzker AGG. 1979. Congenital anomalies causing respiratory failure. In Neonatal Pulmonary Care, Thiebeault D, and Gregory C,
eds. Menlo Park, California: Addison-Wesley, 398. Permission conveyed through Copyright Clearance Center, Inc.
mass, which was felt to be consistent with possible neuroblas- Rotation is not present. The spine and clavicles are straight,
toma. A nonstress test was reactive. with the ribs of equal length on either side of the spine.
The infant required free-flow oxygen and continuous posi- The soft tissues of the neck and chest are of normal thickness.
tive airway pressure by face mask for grunting and retracting The bony framework is intact, with 12 ribs bilaterally and
in the delivery room. He was admitted to the NICU under normal vertebrae.
hood oxygen but weaned to room air at approximately six The tracheal air column is straight, with bifurcation at the
hours of age. His clinical respiratory course was consistent fourth thoracic vertebra.
with transient tachypnea of the newborn (TTN). The hilum appears normal, the thymus is not visible, and the
The infant’s admission physical examination revealed heart is of normal configuration, although a mass overlies the
minimal retractions, with a respiratory rate of 60 per minute. lower cardiac silhouette.
The chest was symmetrical, no masses could be palpated in The diaphragm is between T8 and T9 on the right and at
the abdomen, and the examination was otherwise unremark- T9 on the left.
able. The admission CBC and other laboratory values were The pleurae reach the edges of the bony thorax, and the cos-
within normal limits. Figure 2C-4 shows the first x-ray for tophrenic angles are sharp and clear.
this patient. The intercostal spaces are normal in size.
The lung fields are clear.
X-Ray Evaluation Gastric air is present on the left and throughout portions of
Indication for the x-ray was respiratory distress. the intestinal tract.
Penetration: the x-ray appears to be slightly overpene- A large mass, measuring approximately 4.5 cm by 6.5 cm,
trated because the soft tissues of the extremities are not well overlies the lower cardiac silhouette at the level of the 7th
visualized. thoracic vertebra and extends to the 11th thoracic vertebra.
Neonatal Radiology Basics Lung Pathology: Embryologic Abnormalities 2C-5
R S
ADIOLOGY BASIC
R ADIOLOGY BASICS
FIGURE 4 (cid:31) Admission chest x-ray. Note the large mass overlying the FIGURE 5 (cid:31) Angiogram demonstrating arterial blood supply to the
FIGURE 2C-2 n Intralobar and extralobar sequestrations. FIGURE 2C-4lo nw e Ard cmaridssiaioc ns hcahdeoswt x a-rnady .e Nxtoetned tihneg lianrtgoe t hmea asbs dominal pulmonary sequestration at the level of T9 (feeding
FIGURE 2 (cid:31) Intralobar and extralobar sequestrations. A sequestered FIGURE 3 (cid:31) Scimciatavrit osyvy.nedrlryoimnge. tThhee lhoywpeorp claasrtdici aricg hsht laudnogw m aany dh ave artery). The celiac artery and the superior mesenteric
A sequestereds eseggmmenetn ot fo lfo lboeb eh ahsa ns on bor bornocnhciahl icaol mcommumniucantiicoant iwonit h only two lobes. The pulmonary veins of the lower lobes,
extending into the abdominal cavity. artery are also identified.
with the tracthhee atr. aAcrhteear.ia Al rbtelorioadl bsluopopdl syu ips pfrlyo mis ftrhoem a tohreta a oorr toat ohrer and occasionally the upper lobe, unite to drain into the
systemic vesostehle.r systemic vessel. inferior vena cava (IVC). The large vessel can join the
IVC at its junction with the right atrium or descend to
join the infradiaphragmatic vena cava.
CLINICAL COURSE AND DIAGNOSTIC
minimal retractions, with a respiratory rate of 60 per minute.
FrForomm: :L Luucckk SSRR,, RReeyynnooldlds sM M, a, nadn dRa Rffaefnfsepnesrpgeerr gJ. e1r9 J8. 61.9 C8o6n. gCeonnitagle bnriotna-l WORKUP
bcrohonpcuhlompounlamryo mnaarlfyo rmmaaltfioonrms. aCtuiorrnenst. PCruorbrleemnts Pinr oSbulregmersy i2n3 (S4u)r:g 2e6r0y. The chest was symmetrical, no masses could be palpated in the
The infant underwent a bone marrow aspirate analysis,
RADIOLOG2R3Ye(4p)r:in B2te6Ad0 .b SRy epIperCrimntiSsesdio nw.ith permission from Elsevier. Fromwab:h dLiucochmk SweRn,a R,s e aynnneodgld astt hMive,e a enfxdoa rRm atfiufnemnastpoioerrn gce erw lJ.la s1s,9 m8o6ta.h Ckeoirnnwggie sntehit aeul bndrroieanmg-naorksaisb loef.
cThohpeu lmadomnarisys mioanlfo rCmBatCio nas.n Cdu rroentht Perro bllaembos irna Stourrgyer yv2a3lu(4e)s: 3w00e.re within
neuroblastoma unlikely. Further evaluation on day 2 of life
FIGURE 2C-3 n Scimitar syndrome. Rneporrinmteadl bliym peitrsm. isFsiiognu.re 4 shows the first x-ray for this patient.
Intralobar sequestration (Figure 2) is anomalous lung tis-
FIGURE 2 (cid:31) Intralobar and extralobar sequestrations. A sequestered FIGURE 3 (cid:31) Scimitar syndrome. The hypoplastic right lung may have included a computerized axial tomography (CAT) scan of the
segment of lobe has no bronchial communication with Thsue eh ylopcoaptleadst iwc oritnighlyhi nttw lnuon ologrbm mesa.al Ty lh uhena pvgue l mtoisnosnluya erty w avone idlno sbv oiefs sct.he Terh alole w ppeluer lulmorbaoe nsa,anrdy hypcohpelsats,t aicb. dTohme eann,o amnadl opuesl vpisu,l mwohnicahry r evveeina leddra ain lsa rigneto t hthoeracoab-
the trachea. Arterial blood supply is from the aorta or isv eminoss ot fc tohme lmoawonendr lo ylco clboasecisoa,nt aeandllyd it noh ect chuapesp iloeernf tlao llbloye w,t hueneri tuleop tbpoe ed.rr aRloinab riene,tl oyu, nt hiitte ec an infeXri-oRr avyen Ea vcaavlua.a Ttihoenre may be an associated dextrocardia or
other systemic vessel. bteo dlorcaaint eindt oin ti hnuefe pirnpiofeer rrv ieolnora bv ceeasnv aao c(rIa VvbCai)l .(a TItVheCer a)la.l lrTyg.he e Iv tle asirssge le tc hvaene sjmsoeinol ctshate nc joomin- condIgnoedmniiictnaalat lci oatrundm ifaoocr ra .tnhoem xa-lriaeys. 6w,8as respiratory distress.
the IVC at its jIuVnCc attio itns jwunitchti othne w riitghh tth ea trrigiuhmt a otrri udme socre dnedsc teon djo tion the The infant was intubated and underwent a left thoracot-
minofrna dtyiappeh roafg jsmoeiqnat utihce esv tienrnafratai docianavp.a6h.rTaghmea ctilci nveicnaal cpavrae.sentation may be oPmenye tarnadt iotrna:n stdhiea pxh-rraayg mapaptieca rbsi otop sby eo sf litghhet lmy aosvse. rpPeantheotrlaotgeyd
recurrent pneumonias or other chronic respiratory problems, CASEb ePcaRuEseS EthNeT sAoTftI OtisNsues of the extremities are not well
of the tissue revealed a hamartoma, which is a tumor or mass
such as abscesses of the affected lobe. Therefore, intralobar A fuvilsl-utearlimze 3d..31 kg male was delivered by cesarean section
sequestrations are more frequently diagnosed after the neona- to oRa f3o t4tisa-sytueioaern -ro eilssdu nlgtoriantv gpid rfaer os5em,n pt .af arTail uh3re, e a sbop fi1n e emm aobntrhdye ocr.ll oaTvghiicecl eddse elavirveeel rosyptrmaiegnhtt., A large mass, measuring approximately 4.5 cm by 6.5 cm,
tal period.5 Associated anomalies are less frequent with waTs uhniwsc ioitshm cptohlineca srtiiesbtdes, n oatnf dewq ittuhhae l ailn efdnaingattg hrne oocensii vse eiodthf Aeprp ugsliamdre os conofar rtehys eos sfe pq8iunees.tra- overlies the lower cardiac silhouette at the level of the 7th
intralobar than with extralobar sequestrations.1 andti o9n a. tF oonlleo wmiinngu tteh ea ntdh ofirvaec omtoinmutye, sf.u Trthhee rp rreagdnioangcray pwhaics evalu-
The soft tissues of the neck and chest are of normal thickness. thoracic vertebra and extends to the 11th thoracic vertebra.
Extralobar sequestration (Figure 2) is less common than comatpiolinca tinedc lubdy eidro dn-igdietfaicliizenecdy aanngeimogiar,a ap huyr in(Farigy utrreac 2t Cin-f5ec)-, which
The bony framework is intact, with 12 ribs bilaterally and
intralobar, with a male predominance. The sequestration can tiosnh oduwreindg a t hfeee dfirinstg t rairmteersyte rt,o atnhde ohliagmoharytdormaman/isoesq duuersitnrgation at
normal vertebrae. Clinical Course and Diagnostic Workup
be located above or below the diaphragm, and, unlike with an thet hteh ilredv etrl imofe Tste9r.. During the pregnancy, an ultrasound of
The tracheal air column is straight, with bifurcation at the The infant underwent a bone marrow aspirate analysis,
intralobar sequestration, the anomalous lung tissue is outside the fetUuslt rreavseoaulendd a o pf otshseib mle aasbsd sohmowineadl m thaess .a oSurtbas etoqu been tp porset-erior to
fourth thoracic vertebra. which was negative for tumor cells, making the diagnosis of
the visceral pleura and receives its blood supply from the nattahl em magansse taicn dre tshone ainncfee riimora gviennga o cfa tvhae t foe tbues dcoisnpfliramceedd atnheteriorly.
The hilum appears normal, the thymus is not visible, and the neuroblastoma unlikely. Further evaluation on day 2 of life
aorta, usually below the diaphragm. Associated anomalies— mass, which was felt to be consistent with possible neuroblas-
Venous drainage of the mass was not identified. Fluoroscopy
such as tracheoesophageal fistula, congenital heart disease, toma. hAe anrotn isst roesfs nteosrtm waals croeancftiigvue.ration, although a mass overlies included a computerized axial tomography (CAT) scan of the
of the diaphragm showed normal movement of the right dia-
and diaphragmatic hernia—are more common. Commun- Theth ine flaonwt ererq cuairrdedia cfr esiel-hfolouwe totxey.gen and continuous posi- chest, abdomen, and pelvis, which revealed a large thoraco-
phragm but poor movement of the left diaphragm.
ications with the trachea, bronchi, stomach, and small bowel tiveT ahierw daiya pphrersasugrme bisy bfaectew emeans kT f8o ra ngdru Tnt9in ogn a nthde r reitgrahctt ianngd at T9 abdominal tumor.
An esophagram and upper gastrointestinal study showed
have been reported but are rare. Most extralobar sequestra- in theo dne ltihveer lye frto.om. He was admitted to the NICU under The infant was intubated and underwent a left thoracoto-
displacement of the esophagus anteriorly by the mass, without
tions are diagnosed at an earlier age than are intralobar hooTdh eo xpylgeeunr abeu tr ewaecahn etdh eto e rdogoems oafir tahte a pbpornoyx imthaoteralyx ,s iaxnd the my and transdiaphragmatic biopsy of the mass. Pathology of
sequestrations.6,7 hoaunrso cmoofsa taloigepesh., rfiHesnitsiu clc aalisnn, gioclaerl s c raoernsepn sierhacattoripor yna snc odbu ecrtlsweeae rwe.nas t hcoe nessisotpenhtagus or the tissue revealed a hamartoma, which is a tumor or mass of
Scimitar syndrome (Figure 3) is an anomaly of the entire witoTht hhtreea rni nsgiteaensrttcr tooasicnthatyelp ssntpienaaac ole fss t tarhrueec ntneuowrrebmso aarnln id(nT tsThizeNe m)..ass. tissue resulting from failure of embryologic development.
right lung in which the lung may have only two lobes and is The infant’s admission physical examination revealed
The lung fields are clear. This is consistent with a diagnosis of pulmonary sequestra-
From: Luck SR, Reynolds M, and Raffensperger J. 1986. Congenital bron- IMPRESSION/DIAGNOSIS
chopulmonary malformations. Current Problems in Surgery 23(4): 260. Gastric air is present on the left and throughout portions of tion. Following the thoracotomy, further radiographic evalua-
Reprinted by permission. The infant’s initial respiratory course was consistent
FromFr:o Lmu:c Lku cSkR S, RR, eRyenynoollddss MM,, aanndd R aRffaefnfsepnesrpgeerr Jg. e1r9 8J.6 1. C9o8n6g. eCnoitanl gberonni-tal the intestinal tract. tion included digitalized angiography (Figure 5), which
bronchcohpouplmuolmnaoryn maraylf omrmalaftoiornms.a Ctuiorrnenst. PCruobrrleemnst iPnr Soubrgleemrys2 3in(4 S):u 3rg00e.ry with transient tachypnea of the newborn and not thought
Intralobar sequestration (Figure 2) is anomalous lung tis- 23(4R)e:p 3ri0nt0e.d R beyp preinrmteisdsi owni.th permission from ElsevierN. EONATAL NEtoT bWeO seRcKondary to his congenital pulmonary malformation.
70
sue located within normal lung tissue and visceral pleura and hypoplastic. The anomalous pulmonary vein drains into the
is most commonly located in the left lower lobe. Rarely, it can inferior vena cava. There may be an associated dextrocardia or NEONATAL NETWORK
be located in upper lobes or bilaterally. It is the most com- congenital cardiac anomalies.6,8
mon type of sequestration.6The clinical presentation may b2eC-6 Lung Pathology: Embryologic Abnormalities Neonatal Radiology Basics 71
recurrent pneumonias or other chronic respiratory problems, CASE PRESENTATION
such as abscesses of the affected lobe. Therefore, intralobar A full-term 3.31 kg male was delivered by cesarean section
sequestrations are more frequently diagnosed after the neona- to a 34-year-old gravida 5, para 3, ab 1 mother. The delivery
tal period.5 Associated anomalies are less frequent with was uncomplicated, and the infant received Apgar scores of 8
intralobar than with extralobar sequestrations.1 and 9 at one minute and five minutes. The pregnancy was
Extralobar sequestration (Figure 2) is less common than complicated by iron-deficiency anemia, a urinary tract infec-
intralobar, with a male predominance. The sequestration can tion during the first trimester, and oligohydramnios during
be located above or below the diaphragm, and, unlike with an the third trimester. During the pregnancy, an ultrasound of
intralobar sequestration, the anomalous lung tissue is outside the fetus revealed a possible abdominal mass. Subsequent pre-
the visceral pleura and receives its blood supply from the natal magnetic resonance imaging of the fetus confirmed the
aorta, usually below the diaphragm. Associated anomalies— mass, which was felt to be consistent with possible neuroblas-
such as tracheoesophageal fistula, congenital heart disease, toma. A nonstress test was reactive.
and diaphragmatic hernia—are more common. Commun- The infant required free-flow oxygen and continuous posi-
ications with the trachea, bronchi, stomach, and small bowel tive airway pressure by face mask for grunting and retracting
have been reported but are rare. Most extralobar sequestra- in the delivery room. He was admitted to the NICU under
tions are diagnosed at an earlier age than are intralobar hood oxygen but weaned to room air at approximately six
sequestrations.6,7 hours of age. His clinical respiratory course was consistent
Scimitar syndrome (Figure 3) is an anomaly of the entire with transient tachypnea of the newborn (TTN).
right lung in which the lung may have only two lobes and is The infant’s admission physical examination revealed
NEONATAL NETWORK
70
R S
ADIOLOGY BASIC
FIGURE 4 (cid:31) Admission chest x-ray. Note the large mass overlying the FIGURE 5 (cid:31) Angiogram demonstrating arterial blood supply to the
lower cardiac shadow and extending into the abdominal FIGURE 2C-5p unl m Aonngaioryg rsaemqu desetmraotinosnt raatt tinhge laervteelr oiafl Tb9lo (ofede dsuinpgply Chest X-Ray Findings in
cavity. artetroy )t.h Teh pe uclemliaocn aarrtye rsye qauneds tthraet siounp earti otrh me leesveenlt oerf ic
arteTry9 a(rfee eadlsion gid aerntteirfiye)d. .The celiac artery and the
superior mesenteric artery are also identified. Arteriovenous Malformation
of the Great Vein of Galen
T
he most common neonatal intracranial arteriovenous
malformation (AVM) is an aneurysm of the vein of
Galen.11 This aneurysm presents in the immediate neona-
tal period in 90 percent of cases and predominantly affects
males.12 The primary abnormality consists of multiple arterial
feeding vessels joined via a nidus (central nucleus) to drain-
ing veins. The arterial vessels vary in structure from normally
differentiated arteries to primitive vessels. Histology reveals
arterial vessels that are dysplastic, dilated, and tortuous, with
hyperplastic and disorganized smooth muscle fibers. The
internal elastic lamina of these vessels is fragmented or absent.
The veins are dysplastic with anomalous veinlike channels;
reactive muscular hyperplasia; and degenerative changes of
fibrosis, atrophy, thrombi, and calcification.13
Hemodynamically, there is short-circuiting of the blood
from artery to vein, leading to a cerebrovascular steal and
minimal retractions, with a respiratory rate of 60 per minute. a volume-overloaded systemic circulation. The typically
The chest was symmetrical, no masses could be palpated in the high flow of these malformations results in marked dilation
abdomen, and the examination was otherwise unremarkable. of the feeding arteries and draining veins.13 In some cases,
The admission CBC and other laboratory values were within venous outflow obstruction occurs, and the proximal drain-
normal limits. Figure 4 shows the first x-ray for this patient. ing veins dilate massively. Extremely large aneurysms act like
an intracranial-mass lesion and can obstruct the aqueduct
X-Ray Evaluation of Sylvius, causing hydrocephalus. Brain parenchyma can
Indication for the x-ray was respiratory distress. become necrotic from ischemia, and hemorrhagic infarction
Penetration: the x-ray appears to be slightly overpenetrated can occur as a result of thrombosis within the malformation.
because the soft tissues of the extremities are not well During fetal life, the systemic AVM is in a parallel circula-
visualized. tion with the low-resistance placenta, and flow through the
Rotation is not present. The spine and clavicles are straight, A large mass, measuring approximately 4.5 cm by 6.5 cm, fistula is small. However, the fetal cardiovascular circulation
with the ribs of equal length on either side of the spine. Fololovwerilniegs tthhee lodwiaegrn coasrtdicia ce vsaillhuoautieotnte oatf trhaed iloevgerla pohf st,h eb o7nthe may still be affected in utero, as evidenced by cardiomegaly;
The soft tissues of the neck and chest are of normal thickness. matrhroowra caicsp vierartteiobnra, aanodrt eoxgtreanmds, taon dth eb i1o1ptshy ,t hthoera cdiica gvenrotesibs rao.f cardiac hypertrophy; and cerebral pathology such as hemor-
The bony framework is intact, with 12 ribs bilaterally and extralobar pulmonary sequestration was confirmed. rhage, leukomalacia, and cortical necrosis in neonates who
normal vertebrae. Clinical Course and Diagnostic Workup die soon after birth.14
The tracheal air column is straight, with bifurcation at the TRTEhAe TinMfaEntN uTnd AerNwDen tO aU bToCneO mMarErow aspirate analysis, Following birth, hemodynamic abnormalities resulting
fourth thoracic vertebra. whRicehs ewctaiso nn eogfa tthivee tfuomr otur mwoasr dceellalsy,e md asekcinogn dtharey dtoia gan woosius nodf from the arteriovenous shunting include lowered systemic
The hilum appears normal, the thymus is not visible, and the innefuecrotibolna satot mthae uthnolikraeclyo.t oFmuryt hinerc iseivoanlu saittieo.n D ounr indga ya n2t iobfi oltifice vascular resistance. Compensatory increases in stroke volume,
heart is of normal configuration, although a mass overlies tinhcelruadpeyd f oar ctohme wpuotuenridz eidn faexcitaiol nto, mthoeg irnafpahnyt r(eCqAuTir)e dsc raenin otuf bthae- heart rate, and blood volume lead to an increase in cardiac
the lower cardiac silhouette. tcihoens tf,o ar bpdeorsmisetenn, ta lnedft lpuenlvgi sa, tewlehcictahs irse avnedal edde tae rliaorrgaeti nthgo rreascpoi-- output and eventual high-output heart failure. The increased
The diaphragm is between T8 and T9 on the right and at T9 raabtdoormy sintaatlu tsu.mor. stroke volume and decreased peripheral vascular resistance
on the left. OThne dinayfa n1t6 w oafs liinfetu, btahtee di nafnandt urnedtuerrwneedn tt oa ltehfte thooprearcaotitnog- produce a widened pulse pressure.13 Pulmonary artery pres-
The pleurae reach the edges of the bony thorax, and the rmoyo man dfo trr atnhsed isaupchcreasgsmfual tirce mbioovpasly ooff tthhee smeqasuse. sPteartehdo lotigssyu oe,f sure increases to systemic or near-systemic levels as a result of
costophrenic angles are sharp and clear. wthieth t iscshuees tr etvuebalee dp laa cheammeanrtto. mHae, wwhaisc hs uisc cae tsusfmulolyr oerx tmubasast eodf increased pulmonary blood flow from the malformation and
The intercostal spaces are normal in size. ftoisusur ed aryess uplotisntgo pferroamtiv efalyil uarned owf aesm dbisrcyhoalroggeidc tdoe vheilso ppamreenntts. the normally high pulmonary vascular resistance at birth. The
The lung fields are clear. aTth 2is9 ids acyos nosfi satgene.t with a diagnosis of pulmonary sequestra- right ventricle ejects an increased volume of blood against
Gastric air is present on the left and throughout portions of tion. Following the thoracotomy, further radiographic evalua- high pulmonary artery pressure. A right-to-left shunt occurs
the intestinal tract. Rtieovnise din acnldu udpeddat edd ifgroimta:l Sizalemdo nasn Sg. 1io99g5r.a Ppuhlmy o(nFariyg sueqreue s5tr)a,t iownh. ich across the ductus arteriosus and foramen ovale as a result of
Neonatal Network 14(6): 69–73. Used with permission of Springer
high pulmonary artery pressure and lower systemic vascular
Publishing Company, LLC, www.springerpub.com/nn.
resistance.11,15
NEONATAL NETWORK
71
Neonatal Radiology Basics Lung Pathology: Embryologic Abnormalities 2C-7
TABLE 2C-2 n Chest X-Ray Findings in Arteriovenous FIGURE 2C-6 n Chest x-ray of a term neonate presenting with
Malformation of the Great Vein of Galen cardiomegaly. See “Chext X-Ray Evaluation” for
discussion of findings.
• Cardiomegaly, with more prominent right atrial and right
ventricular enlargement
• Widening of the superior mediastinum
• Anterior displacement of the upper airway and pharynx
• Posterior displacement of the intrathoracic portion of the trachea
Adapted from: Swischuck LE. 2004. Imaging of the Newborn Infant
and Young Child, 5th ed. Philadelphia: Lippincott Williams &
Wilkins, 1058–1061.
The initial response of high output heart failure is fol-
lowed by volume overload, decompensation, and low-output
failure. A large volume of blood shunting through the aneu-
rysm commonly leads to congestive heart failure secondary to
high-output failure in the early neonatal period. Frequently,
cardiac findings are so acute that a cardiac disorder is the
usual primary presumed diagnosis.
Clinical features can include cyanosis from right-to-left
shunting through the ductus and/or foramen ovale and
decreased peripheral perfusion. A wide pulse pressure is
present. The heart is hyperdynamic. Upon auscultation, a
split second heart sound; a louder-than-normal second heart normal; the thoracic portion of the trachea appears more pos-
sound from pulmonary valve closure; and in some cases, if terior, whereas the upper airway and pharynx have a more
marked failure is present, a third and a fourth heart sound anterior displacement. These changes occur secondary to the
may be heard. Systolic murmurs resulting from tricuspid large dilated brachiocephalic vessels pushing the intratho-
regurgitation or increased flow through the valves may be racic portion of the trachea back and the upper airway and
present. Arteries proximal to the malformation experience pharynx forward. Less commonly, the chest x-ray presenta-
increased pulsations and those distal, decreased pulsations, tion is that of cardiomegaly with slightly decreased pulmo-
leading to increased carotid pulsations and decreased femoral nary vasculature. It has been theorized that this presentation
pulses. Murmurs may be auscultated over the area of the mal- occurs as a result of normal hemodynamic changes in the
formation as a result of flow turbulence in the area, and bruits immediate postnatal period: increased pulmonary vascular
may be auscultated. Hepatomegaly occurs as congestive heart resistance and a right-to-left shunt through the patent ductus
failure evolves.15,16 arteriosus and foramen ovale causing excess pulmonary blood
A more rapid diagnosis can be made if the presence of flow and pulmonary vascular changes leading to pulmonary
a continuous cranial bruit, usually found over the poste- hypertension.18
rior cranium, is detected early. Once fulminant congestive Echocardiography shows normal cardiac structure,
heart failure occurs, a decrease in cervical venous pulsations enlargement of the right atrium and ventricle, or four-cham-
and a less audible bruit result.17 Typically, the first diagnos- ber cardiomegaly.15 A right-to-left shunt may be seen at the
tic impression is ductal dependent congenital heart disease ductal or atrial levels. Detection of dilation of the descending
with high-output cardiac failure. Coarctation of the aorta is aorta and superior vena cava in subxiphoid and suprasternal
often considered because of the difference between the pulses views can strongly suggest the diagnosis of cerebral AVM.13
and the rapid onset of cardiac failure. A positive response to A diastolic reversal of blood flow on the transverse aortic
prostaglandin E1 had been reported in two cases of neonates arch may be seen in some cases, aiding diagnosis. Diagnostic
with AVM, a response that may further delay accurate diag- considerations should include causes of cardiomegaly with a
nosis. Right-to-left shunting at the ductal and atrial levels, structurally normal heart.
evidenced by a PaO gradient of 10 torr, may also prompt the Early detection provides the neonate with the best chance
2
diagnosis of pulmonary hypertension.15 for effective treatment and intact survival. Ultrasound, mag-
The usual chest x-ray findings include cardiomegaly with netic resonance imaging, and computerized tomography
pulmonary congestion and increased right atrial and right (CT) can demonstrate and delineate the characteristics of the
ventricular size (Table 2C-2). These changes occur second- malformation. Ultrasound is a useful and convenient tool for
ary to increased venous return to the right atrium from the bedside assessment of the critically ill neonate. Angiography
malformation. The superior mediastinum appears wider than
2C-8 Lung Pathology: Embryologic Abnormalities Neonatal Radiology Basics
FIGURE 2C-7 n CT showing an arteriovenous malformation of physical exam was positive for a 39-week, AGA male with a
the great vein of Galen, ventriculomegaly, and soft anterior fontanel, an active precordium, a Grade II–III
calcifications. systolic ejection murmur at the left sternal border with wide
radiation over the precordium, a liver 2.5 cm below the right
costal margin, decreased perfusion and slight mottling of the
lower extremities with decreased femoral pulses, and a blood
pressure of 50 systolic and 28 diastolic with a hematocrit of
50 percent. The neonate’s responsiveness to stimulation,
tone, and activity was decreased. The admission diagnoses
were term AGA male, perinatal asphyxia, respiratory depres-
sion, hypotension, cardiac murmur—rule out congenital
heart disease, patent ductus arteriosus shunting, pulmonary
hypertension, and sepsis.
The patient was maintained on low ventilatory settings,
given 10 mL/kg of volume expansion, and started on
10 mcg/kg/minute of dopamine for persistent hypoten-
sion. A chest x-ray (Figure 2C-6) was taken (see following
evaluation). An echocardiogram was obtained; it revealed
pulmonary hypertension with a right-to-left atrial and ductal
shunt. A sepsis workup was obtained and antibiotics begun.
Cardiology was consulted; their impression was probably pul-
monary hypertension with no structural heart disease. On
day 2, the patient’s neurologic status remained abnormal and
congestive heart failure unresponsive to management. These
findings prompted evaluation for a cranial bruit, which was
present over the posterior cranium. A computerized tomog-
raphy scan was obtained (Figure 2C-7). The CT scan demon-
strated a large AVM involving the cortex and right temporal,
parietal, and occipital lobes; calcifications; intraventricular
can further establish the nature of the AVM’s blood supply hemorrhage; and hydrocephalus. Following the results of the
and drainage. CT scan and after neurology and neurosurgical consultation,
The treatment of choice for AVM in recent years is inter- the parents requested that life support be withdrawn.
ventional radiology. Transcatheter occlusion of the feeding
arterial branches of the AVM can be carried out with acrylic Chest X-Ray Evaluation
polymers, wire-fiber microcoils, or both.14 The success of this Indication for the x-ray was initial evaluation following deliv-
embolization procedure is quite variable. Permanent brain ery room resuscitation, intubation, and umbilical artery line
damage is a risk, and the AVM may recur as new feeding placement and admission to the NICU.
channels open up.11 Penetration appears to be normally exposed.
Rotation is slightly toward the right.
CASE STUDY The soft tissues of the neck, chest, and abdomen appear to
A 3,300 g, AGA, term male neonate was delivered by be of normal thickness.
spontaneous vaginal delivery to a 24-year-old, gravida 3, para The bony framework is intact, with 12 ribs bilaterally. The
0, ab 2 mother. This mother had prenatal care beginning in clavicles are intact, and the humeri and vertebral bodies are
the second trimester. Her serology and hepatitis B surface without abnormality.
antigen were negative, her blood type was A positive, and her The trachea shows a straight air column. An endotracheal
rubella status was immune. The pregnancy and labor were tube is positioned at the second thoracic vertebra (T2). The
unremarkable, and rupture of the membranes occurred 12 right and left mainstem bronchi are visible over the heart.
hours before delivery. The infant required resuscitation fol- The hilum shows a wide opacified mediastinum. The heart
lowing birth for lack of respiratory effort and a heart rate is markedly enlarged, with a cardiothoracic ratio of 0.75. No
of 70. Following bag and mask ventilation and cardiac com- distinctive pattern of heart shape is appreciated.
pressions, the newborn was intubated and transferred to The diaphragm on the right is slightly domed, with expan-
the NICU. Apgar scores were 1, 6, and 8 at one, five, and sion to the ninth thoracic vertebra, and the diaphragm on the
seven minutes. After admission to the NICU, the patient was left at the tenth vertebra is consistent with an inspiratory film.
placed on intermittent mandatory ventilation. The admission
Neonatal Radiology Basics Lung Pathology: Embryologic Abnormalities 2C-9
R S
ADIOLOGY BASIC
FIGURE 1 (cid:31) The gastrointestinal tract: S–Stomach, D—Duodenum, FIGURE 2 (cid:31) Abdominal x-ray showing a single gastric bubble.
J–Jejunum, SI–Small intestine, I–Ileum, A–Appendix,
C–Caecum, AC–Ascending colon, TC–Transverse colon,
The pleura reach the edge of the bony thorax. Normal cos- FIGURE 2C-8D Cn – TDhees cgeansdtirnogin ctoelsotnin, aSlC t–rSaicgtm. oid colon, R–Rectum
tophrenic angles are seen.
Gastric air is present on the left, and a feeding tube is posi-
tioned in the stomach. Air is present throughout the intestine.
Lung fields are somewhat difficult to evaluate because of car-
diomegaly. They appear lucent and have increased pulmonary
vascular markings.
The endotracheal tube is located at T2, and an umbilical
artery line lies to the left of the vertebral column at T7.
The impression is cardiomegaly with a wide mediastinum
and increased pulmonary blood flow. The endotracheal tube
and umbilical artery line are in acceptable positions. Based on
this initial chest x-ray, congenital heart disease is suspected.
With the additional data of an echocardiogram showing a
S
structurally normal heart, the diagnostic possibilities listed in
Table 2C-2 should be considered.
TC
D
Revised and updated from: Carey BE. 2000. Chest x-ray findings in
J
arteriovenous malformation of the great vein of Galen. Neonatal Network
19(3): 71–74. Used with permission of Springer Publishing Company,
LLC, www.springerpub.com/nn.
DC
AC SI
Situs Inversus Totalis
I
E
xternally, the human body appears symmetric; if a line is C intestinal wall (i.e., “double wall sign”): The intestine is
drawn down the middle of the body, each side appears A SC outlined by air in the peritoneum and air in the intestinal
identical. However, this is not true of the internal anatomy. lumen. This is best appreciated on the lateral film.
For example, there is one heart, which lies in the left chest, R 4. Evaluate for the presence of radiodensities such as calcifica-
one liver, in the right abdomen, and one stomach, in the left tions and air fluid levels. If these exist, calcifications within
abdomen. The term situs refers to the position or location of Key: S–stomach, D–duodenum, J–jejunum, SI–small intestine, or around the bowel will be seen as white masses and a
an organ, specifically, the position of the atria and abdominal sI–triluecutmu,r eAs–,a wppheincdhi xi,n Cc–lucdaeec uthme, AvCer–taesbceranld cinogl ucomlonn,, lToCw–er ribs, bowel filled with fluid will cast vague and confluent gray
viscera in relation to the midline of the body.19 There are three atrnands vpereslev cios.lo nN, oDCte– daenscye nadsinygm cmoloent,r SyC. –Tsighme opidl acocleomn, eRn–t of shadows.5 Calcifications may be caused by sterile meconi-
rectum.
types of situs: solitus, inversus, and ambiguous. Situs solitus Frocmat:h Qeuteinrns, Dif, aanndy ,S ihna nanbodno LmF.i n19a9l 5v.e Cssoenlgs esnhitoaul aldn obme anlioest eodf .the um peritonitis, which appears as small, rounded opacities;
refers to the normal arrangement of organs, with the right 2. Ngaesxtrto ienxteasmtininale t rtahcet. Psoarftt I :t iTshseu setso mofa cthh.e N leeofnta utapl pNeertw qourka 1d4r(a8n):t , renal calculi; teratomas that are retroperitoneal; or
atrium, liver, gallbladder, trilobed lung, and inferior vena cava r6i4g.ht upper quadrant, both flanks (the outer lateral neuroblastoma.
on the right side and the left atrium, stomach, spleen, bilobed areas of the abdomen), mid-abdomen, and pelvis. In
lung, and descending aorta on the left side (Figures 2C-8– each quadrant, check for normal organ masses (i.e., DEVELOPMENT OF THE STOMACH
2C-10). Situs inversus totalis refers to a mirror image reversal is rlievleevr,a nspt.l eEenar, lya nidn sdtoemvealochpm). eAnnt,y tshheif te mofb orrygoa niss osyrm inmteest-- Development of the gastrointestinal tract, an early event,
of the normal position of the internal organs (Figures 2C-11 ric,t ibnoet hfr osimde tsh bee ninogr midael nloticcaatl.i2o0n T shheo uhelda rbt eb negoitnesd .formation begins during the fourth week of gestation and is completed
and 2C-12).19 The incidence of situs inversus totalis is 1 in 3at. Aapspsersosx tihmea cteolnyt e1n8t s doafy tsh ge eGstIa ttiroanct .w Litoho kth aet tahpep eaabrdaonmcei noafl by the tenth week.6 The stomach arises during the fourth
every 8,000 to 25,000 births, and the condition is most often paicreodn tcoaurrd ifaocr tbuublegsin.2g2 Aflat nakpsp oror xmimiladt etloy m22a rkdeadys dgisetsetnattiioonn., week of gestation as a spindle-shaped dilation of the
diagnosed by radiographic examination.20 Situs ambiguous, theD ciasrtdeniatcio tnu bmeasy l ebneg dthueen t oa npdh yrsoitoaltoeg tico othr est rriugchtut.r aTl hoibs sitsr tuhce- foregut.6,7 In the subsequent weeks, the stomach dilates and
often referred to as heterotaxia, is the random arrangement of firstti osing no ro af cacsoymmpmaneytr yre isnp irtahteo reym dbirstyroe.s2s3 oTrh me ercohtaantiiocnal ovfe nthtie- rotates, resulting in a change in appearance and position.
the internal organs and is associated with splenic abnormali- healartt,io wnh. iFcho lilso wof ttehne ccaolluedrs elo oopfi naigr, tish roonueg ohfo tuhte tmheo sGt Iim trpaocrt-, The rotation is around a longitudinal and anterioposterior
ties and congenital heart disease.21 The purpose of this article tankte setpeipnsg i nin f omrimndat itohne abgeec aoufs teh iet pdaettieernmt ianneds tthhee nstorrumctaul rper oo-f axis. The effects of this longitudinal rotation are (1) the lesser
is to discuss the embryology, pathophysiology, and diagnosis twog rseespsiaorna toef sayisrt tehmros ufgohr pthuem GpIin tgra cbtl opoodst.n20a Ttahlley. aAp ecxo mofp ltehtee curvature moves to the right, (2) the greater curvature moves
of situs inversus totalis and to review a case study with radio- heaorbt smtrouvcetiso fnro wmi ltl hcea urisgeh to psiadcei toy f dtihseta tlh toor atxh eto o tbhset rluefctt isoidne. to the left, (3) the original left side becomes the ventral sur-
graphic findings. in tLhoeo nke fxotr 1 f0re–e1 2ai rd. aAys ,l abrgye w choilclehc ttiiomne omf ofrset eo af itrh we ihll elaeratd l iteos face, and (4) the original right side becomes the dorsal
in tahbed loemft icnhale sdti.s2t2e Dnteioxtnr oacnadr daina reelesvualttse dw hdeianp hthraeg hme,a ratn fda iolsu tto- surface.7,8 During the anterioposterior rotation, the caudal
EMBRYOLOGY AND DEVELOPMENT miglirnaetes tsotr tuhcet ulerfets tshuocrhax .a sS itthues ifnavlcerifsours mto tlailgias mreesnultt.s Swmhaelnl (pyloric) portion moves to the right and upward, whereas the
The majority of literature published to date on embryo- thea mcaorduinatcs toufb efrse ero atairt em taoy thbee leevfitd aenndt othne epitlahceerm siednet ooff tthhee cephalic (cardiac) portion moves left and downward.6
logic factors predisposing to situs inversus totalis focuses on heart and other internal organs presents a mirror image of the
abnormal development of the heart. Therefore, a discussion normal arrangement. In other words, the liver is in the left
of the mechanisms controlling heart rotation and migration abdomen, the stomach is in the right abdomen, the trilobed
NEONATAL NETWORK
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2C-10 Lung Pathology: Embryologic Abnormalities Neonatal Radiology Basics