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925

Pictorial

Large

Intrathoracic S. Ablin

Deborah

,

E. Michel

Tumors

Azouz2,

Kiran

in Children:

Bony

and Soft-Tissue

Tumors

of the Chest

Wall

August

Presented 1 Department to D. S. Ablin.

2Department

29, 1994; accepted

after revision

at the annual meeting of the American of Radiology,

University

of Diagnostic

Imaging,

AJR 1995;i65:925-934

of California, Hospital

036i-803X195/1654-925

the only imaging technique that can show bone involvement, on it may show more extensive bone involvement than can be seen on plain films on CT scans. Ewing’s sarcoma (Fig. i) is the most common primary malignant skeletal tumor of the chest wall in children [i 2]. It classically causes a permeative lytic expansile lesion of the nib with cortical and medullary destruction, peniosteal reaction, and an associated soft-tissue mass that is homogeneous on CT scans (Fig. 1). When the soft-tissue component is massive, bone involvement, a key identifying feature, may be very subtle on difficult to recognize without CT scans obtained at bone windows on a bone scan. Although rare, malignant PNET arising from the chest wall ,

is typically

Most large intrathoracic tumors that anise from the chest wall are primary and malignant and include Ewing’s sancoma, rhabdomyosancoma, and malignant primitive neunoectodermaltumon (PNET, onAskin tumor) [1-4]. The majority of these large chest wall tumors occur in children olden than 710 years [i-4]. Early imaging clues that suggest the site of origin as the chest wall include recognition of subtle on obvious bony destruction of the nibs on vertebrae on plain films on CT scans on detection of soft-tissue extension into the chest wall on CT scans on MR images. Bone scintignaphy may be

Received

Findings

A. Jam

Massive benign or malignant thoracic tumors in children may arise from the chest wall, pleura, lung parenchyma, or mediastinum and may be primary or secondary. On initial chest radiographs, these masses usually appear as an opaque hemithorax or an obvious large opaque mass. If the site of ongin of the intrathoracic tumor can be determined, the differential diagnosis may be based on the location of the tumor, the age of the patient, and distinguishing imaging features. The purpose of this essay is to illustrate imaging findings of large intrathoracic masses that cause an opaque hemithorax on mitial chest radiographs. Chest wall masses that do not grow pnimanly lntrathoracically are not Included in this discussion.

Large

Imaging

Essay

large

(Fig.

2) and

is an

undifferentiated

small-

round-cell tumor derived from embryonal cells of the neural crest [3]. Key identifying features include chest wall involvement, nib destruction, pleural involvement, and/on muscle invasion (Fig. 2). MR images may be helpful in identifying muscle invasion of the chest wall, and CT scans may aid in identifying pulmonary metastasis. PNET is heterogeneous on CT scans and MR images because of hemorrhage and/or necrosis in the mass. Calcification in PNET is unusual, although it was seen in our case [3]. PNET must be distinguished histologically from other small-round-cell tumors of

,

April 21 199S. Roentgen Ray Society, New Orleans, April 1994. Davis

Medical

for Sick Children,

American

Center, University

Roentgen

Ticon

II Bldg., 2516

of Toronto,

Ray Society

Stockton

555 University

Blvd.,

Sacramento,

Ave., Toronto,

Ontario

CA 95817. MSG

Address

1X8, Canada.

correspondence

ABLIN

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926

ET

AL.

AJR:165,

October 1995

Fig. 1.-Ewing’s sarcoma of left sixth rib in 13-year-old boy. A, Anteroposterior chest radiograph shows opaque left hemithorax with apical pleural fluid (arrowheads). Note classic 9-cm-long lytic expansile permeative destructive lesion of left sixth anterolateral rib (black arrows) characteristic of Ewing’s sarcoma and shift of mediastinum and trachea (white arrows) to right. B, Contrast-enhanced CT scan of chest shows bony destruction in left sixth rib (black arrows) indicating site of origin of associated homogeneously enhancing, lobulated, intrathoracic soft-tissue mass (open white arrows). Characteristic of Ewing’s sancoma, soft-tissue mass extends onto chest wall (arrowheads). Mediastinum and aorta (A) are shifted to right, and left lung is partially collapsed (solid white arrows) because of mass effect. Large pleural effusion contributing to mass effect is present. Homogeneous appearance of intrathoracic soft-tissue mass in Ewing’s sarcoma is helpful in distinguishing this tumor from PNET, which also arises from chest wall but frequently has inhomogeneous intrathoracic soft-tissue mass (see Fig. 2). C, Contrast-enhanced CT scan of chest, late in bolus, shows multiple homogeneous diaphragmatic metastatic implants (arrows), indicating malignant lesion. Aorta (A), only faintly enhanced, is displaced to right because of mass effect. Large pleural effusion is present. D, Delayed planar image (oblique magnified view) of bone scan of left ribs shows irregular increased uptake of radionuclide in anterior and lateral left sixth rib (arrows), localizing site of origin of mass to rib of chest wall.

F

‘: . .

A

I

_f I_

I

I

-

1)

D childhood that cause large intrathonacic masses, which include neunoblastomas, nhabdomyosancomas, other soft-tissue sarcomas, Ewing’s sarcomas, and lymphomas [2, 4]. Benign and metastatic bony chest wall tumors are usually small and are not considered in the differential diagnosis of large intrathonacic masses at presentation. However, when a malignant metastatic bone lesion does become large, the primary site and diagnosis are already known [i 2]. The most common extrapleunal nonskeletal chest wall softtissue tumor in children is rhabdomyosarcoma, and it may grow primarily intrathoracically [2, 4]. Other intrathonacic softtissue sarcomas that may occur include undifferentiated sancomas, malignant mesenchymomas, PNETs, extnaosseous Ewing’s sarcomas, and other rare sarcomas (i.e., Ieiomyosarcomas, fibrosancomas, and hemangiopenicytomas) [i 2, 4]. Although the majority of large intnathoracic rhabdomyosancomas or other soft-tissue sarcomas arise from the chest wall, ,

,

the exact site of origin may be difficult to determine (Fig. 3). Two percent of these sarcomas anise outside the chest wall, from

the

mediastinum

(Fig.

4),

pleura,

on lung

panenchyma

(Fig. 5). For those arising outside the chest wall, the mediastinum is the most common site [4]. Eighty-two percent of intrathoracic sarcomas are unresectable at diagnosis because of widespread infiltration, encasement, on compression of vital structures and are best shown by CT [4] (Figs. 3B and 4). High-density pleural fluid attributable to hemorrhage may occur. Rhabdomyosarcomas and other soft-tissue sarcomas involve bony structures less commonly than do Ewing’s sarcomas and PNETs, but when bone is involved they may mimic other tumors arising from the bony chest wall on posterior mediastinum [2]. Lange benign intrathonacic soft-tissue chest wall tumors, such as lipomas, lipoblastomas, lymphangiomas, and benign mesenchymomas, are uncommon in relation to malignant

AJR:165,

LARGE

October 1995

INTRATHORACIC

TUMORS

927

IN CHILDREN

Fig. 2.-Primitive neuroectodermal tumor (PNET) of chest wall in li-year-old girl. A, Chest radiograph shows opaque left hemithorax with marked shift of mediastinum and trachea to right (solid arrows), narrowing of carinal angle (asterisks), and small left apical pleural effusion relative to amount of shift, suggesting solid mass. Per-

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meative destruction,

erosion, and splaying of left seventh through

ninth posterolateral

ribs (arrowheads) indicate mass arising from chest wall. Left hemidiaphragm is inverted as soft-tissue mass indents into upper abdomen (open arrow), indicating its large size. B, Contrast-enhanced CT scan of chest shows large left-sided intrathoracic inhomogeneously and slightly enhancing mass involving left ribs (black arrows) and extending between ribs to left chest wall (solid white arrows), indicating its origin from chest wall. Mass extends anterior to aorta to right of midline (open white arrow). Areas of necrosis and/or hemorrhage within mass are responsible for its heterogeneous appearance on CT scans and MR images (not shown). This heterogeneous appearance of soft-tissue mass is

helpful in distinguishing PNET from Ewing’s sarcoma, which also originates from chest wall but has homogeneously appearing soft-tissue mass. Both Ewing’s sarcoma and PNET may have associated rib destruction and soft-tissue chest wall involvement. C and D, Delayed planar images of bone scan, posterior (post) (C) and anterior (ant) (D) views, show increased uptake in left fifth through 10th ribs and show more extensive bony involvement than was visible on plain film or seen in the Ewing’s sarcoma case (Fig. 1 ). Radionuclide uptake is increased in mass in left hemithorax because of microcalcifications that were not visible on CT scan. Oblique linear areas of increased uptake crossing right upper ribs near midline and over left iliac wing are related to Broviac catheter and IV tubing, as confirmed by oblique views (not shown).

.‘

a

..

post

ant

C

bony on soft-tissue masses included in the differential masses [2]. Identifying fat images may be helpful in lipoma on lipoblastoma.

Large

Pleural

and Lung

of the chest wall but should be diagnosis of lange intrathoracic in a mass on CT scans on MR identifying a large intrathonacic

Parenchymal

Tumors

Most intnapulmonary tumors in children are benign and, except for cystic adenomatoid malformations, bnonchogenic cysts, and congenital loban emphysema, rarely become massive on manifested by an opaque hemithonax on chest radiographs. Cystic adenomatoid malformations are classified into

D

three types and are manifested in the neonatal period when they are large. Type I, the most common, consists of a few large cysts 3-i 0 cm in diameter. Type II consists of numerous small to medium cysts, 0.5-3.0 cm in diameter. Type III, the most severe form, occurring in only i 0% of cases, usually involves the entire lobe on lung and consists of diffuse microscopic cysts that appear as a solid mass on imaging [5]. Large cystic

adenomatoid

malformations

of types

I and

II and

panen-

chymal bronchogenic cysts are usually easily distinguished from other large solid intrathonacic masses because of the presence of air and/on fluid within the variably sized cysts, as shown by plain radiography, CT, and/or sonography [5, 6]. Lange cystic adenomatoid malformations of type Ill and panen-

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A

B

Fig. 3.-lntrathoracic A, Chest radiograph,

undifferentiated sarcoma in 7-year-old girl. posteroanterior view, shows complete opacification of left hemithorax with shift of mediastinum and trachea to right (arrows) and narrowing of carinal angle (asterisks ), suggesting solid mass. Ribs are not involved, suggesting that mass did not originate from ribs. B, Contrast-enhanced CT scan of chest shows inhomogeneously enhancing mass filling left hemithorax and shifting trachea (T), esophagus (E), and vessels to right. Mass shows its frequently malignant unresectable nature by encasing left common carotid artery (arrow) and left subclavian artery (asterisk). Chest wall is not involved. Exact site of origin of mass, exclusive of chest wall, could not be determined by imaging. Among all large solid intrathoracic tumors not Involving chest wall, most marked amount of inhomogeneous contrast enhancement on CT scans is seen in soft-tissue sarcomas and in rhabdomyosarcomas (see Figs. 4 and 5). S = superior vena cava receiving left brachiocephalic vein, B = brachiocephalic artery.

4

5

Fig. 4.-Alveolar rhabdomyosarcoma chest, obtained after chest radiograph

vena cava and inferior vena cava in i-year-old boy. CT scan of inhomogeneously enhancing intrathoracic mass arising from mediastinum, shifting ascending aorta (A) to left and displacing right bronchus posteriorly (black arrow) because of mass effect. Because of local malignant extension typical of this type of tumor and other soft-tissue sarcomas, superior vena cava (arrowhead) was compressed by mass; body wall edema is related to superior vena cava obstruction. Small left pericardial and pleural effusions (white arrows) and atelectasis of right lower lobe of lung from bronchial compression are apparent. Inferior vena cava (not shown) was also compressed by mass as it extended inferiorly to fill right hemithorax. Typical of rhabdomyosarcoma, this mass was unresectable at diagnosis. Because lymphoma commonly originates in anterior mediastinum and frequently causes superior vena cava obstruction, It would be considered in differential diagnosis but would not typically show this amount of inhomogeneous contrast enhancement. Fig. 5.-Large-cell nearly completely large intrathoracic in other sarcomas

and encasement graph

of mediastinum showed opaque

with obstruction of superior hemithorax, shows right-sided

soft-tissue sarcoma of lung in 3.5-year-old girl. Contrast-enhanced CT scan of chest was obtained after chest radiograph showed opaque right hemithorax with small apical pleural stripe relative to amount of shift of mediastinum and trachea to left, suggesting mass. CT scan shows mass occupying most of right hemithorax with inhomogeneous enhancement, similar to enhancement seen and rhabdomyosarcomas (Figs. 3B and 4). Right lower lung (arrowheads) is collapsed medially because of bronchial compression

above this level. Air within mass is result of attempted

was mistaken

for large

pleural

effusion

by clinician.

thoracentesis,

which was performed

after opaque hemithorax

on chest radio-

AJR:165,

October

LARGE

1995

INTRATHORACIC

TUMORS

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chymal bronchogenic cysts associated with complex fluid, obstructive pneumonia, on compression of a bronchus resulting in atelectasis may be confusing, as they mimic other large solid intrathoracic tumors. Congenital loban emphysema, which occurs in the upper and middle lobes, appears as a solid mass on plain films only when

filled

with

fluid

in the

immediate

neonatal

period;

pulmonary

and

pleural

rhabdomyosarcomas,

of the “mass” it

soft-tis-

sue sarcomas (Fig. 5), pulmonary blastomas, malignant mesenchymomas, Ieiomyosarcomas, and pleural mesotheliomas [4, 5, 8]. Mesenchymal sarcomas, rhabdomyosancomas, and pulmonary blastomas may arise from preexisting cystic lung lesions (including cystic adenomatoid malformations) or from mesenchymal cystic hamartomas [5, 8]. In children, secondary malignant metastatic lung and pleural lesions, such as osteogenic sarcomas or Ewing’s sancomas (Fig. 7), rarely have been reported to become massive; usually the primary lesion is already known [i 6]. The most common diseases that mimic large pulmonary or pleural masses are large consolidating pneumonias or ,

Fig. 6.-Plasma cell granuloma of lung in 10-year-old boy with cough. A, Anteroposterior chest radiograph shows lobulated mass containing calcifications (arrow) in base of right hemithorax. No rib involvement or pleural fluid is apparent. B, CT scan of chest shows large lobulated mass in right lung with extensive

calcifications and no pleural fluid, characteristic features of plasma cell granulomas. No rib or vertebral Involvement is noted to suggest posterior mediasti-

nal mass, such as ganglioneuroblastoma or ganglioneuroma, which could contain similar calcifications in patients of similar age. Although teratomas and

germ cell tumors may contain similar calcifications, they occur in anterior mediastinum and would have additional tissue elements, unlike plasma cell granulomas. Because plasma cell granulomas may be difficult to distinguish on imaging from malignant neoplasms, such as pulmonary blastoma, surgery is treatment of choice.

929

pseudotumors, large pleural fluid collections, large fluid-filled abscesses, or combinations of these (Fig. 8). These abnormalities are most rapidly recognized by CT on sonography [1]. Findings on CT scans suggesting the possibility of an inflammatory or infectious origin of the mass include (1 ) visualization

should not be considered in the differential diagnosis of large intnathoracic masses beyond this time [5]. Pulmonary sequestnations may be manifested as masses at any age but are usually located in the lung bases and are not massive [5]. Plasma cell granuloma, a rare benign lung parenchymal tumor consisting predominantly of mature plasma cells (Fig. 6), is an inflammatory pseudotumor that is usually well cmcumscnibed, with frequent calcifications and no associated pleural effusion. It may rarely contain central cavitation. Patients are usually asymptomatic but may have cough, fever, chest pain, and hemoptysis. This tumor has rarely been reported to become large [7]. Large primary malignant lung on pleural tumors are rare, but those that have been reported to become massive include

IN CHILDREN

on both

sides

of a fissure

containing

pleural

fluid,

an unlikely method of spread for a solid tumor; (2) multiple bculated rim-enhancing pleural fluid collections; (3) Iow-attenuation nodes with or without rim enhancement; and (4) the presence of abnormal air collections not seen on plain film (Fig. 8). Low-attenuation nodes should alert the radiologist to consider granubomatous disease, especially tuberculosis.

Large The

Mediastinal

Tumors

mediastinum

is

the

most

common

location

for

intrathoracic masses in children, and the differential diagnosis is best approached by use of mediastinal compartments [9]. CT or MR imaging or both are most useful in localizing large intrathoracic masses to the anterior, middle, or postenor mediastinum and in showing the overall extent and relationship

of masses

Anterior

Mediastinum

to vital

structures.

The majority of large intrathonacic masses of the anterior mediastinum are lymphomas (Fig. 9), thymic infiltration from lymphomas or leukemia, other thymic lesions, teratomas, and malignant germ cell tumors. Lymphomatous masses enlarge the thymus

and create

lobulated

borders,

compress

the airway

and vital structures, and may have associated adenopathy, pleural effusion, on chest wall involvement [9]. The presence of calcifications, fat, and/or cysts within the mass distinguishes tenatomas and germ cell tumors from other anterior mediasti-

ABLIN

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930

ET AL.

AJR:165,

October

1995

A Fig. 7.-Metastatic pulmonary osteogenic sarcoma with endotracheal and left endobronchial lesions in 17-year-old boy. Patient had primary osteogenic sarcoma of right femur and previous resection of metastatic nodules in base of left lung. A, Anteroposterior chest radiograph shows completely opaque left hemithorax with shift of trachea (black arrows) and mediastinum to left. Calcified metastatic nodules (white arrows) are present In right lung. Left main bronchus is not aerated because of endobronchial lesion. B, Unenhanced CT scan of chest shows shift of mediastinum (M) to left and soft-tissue-density mass containing metastatic ossification (solid arrows) typical of osteosarcoma. Right main bronchus (B) is visualized, and left bronchus and left lung are not aerated because of endobronchiai lesion. Arrowhead indicates right pulmonary artery. Calcified metastatic pulmonary nodule is present in right lung (open arrow). No rib destruction or chest wall extension is associated to suggest tumor arising from bony chest wail.

Fig. 8.-Pseudotumor

attributable to pulmonary tuberculosis and superimposed bacterial pneumonia with empyema and adenopathy in 8-year-old for medical attention after two episodes of acute hematemesis, 2 weeks of fevers, and 6 months of chronic cough, fatigue, and weight loss. Boy’s mother subsequently had pulmonary tuberculosis diagnosed. A, Anteroposterior chest radiograph obtained at admission shows opaque left hemithorax with left pleural fluid collection (white arrowheads) and associated tracheal deviation to right (solid arrows), Indicating mass effect. Mediastinal adenopathy is seen in right lower paraspinal region (open arrow). Subtle periostitis of left seventh and eighth anterior ribs, related to infection, is present (black arrowheads). B, Contrast-enhanced CT scan of chest obtained at admission shows diffuse consolidation of left lung and complex loculated left pleural fluid collection with curvilinear and rim enhancement, suggesting inflammation or infection. Areas of curvilinear enhancement surrounding areas of necrosis are visible in lung. Pleural fluid is seen in major fissure (black arrows) with abnormal lung on both sides, indicating consolidation and not mass. Small pericardlal effusion is present (arrowheads). Associated low-attenuation adenopathy (white arrows) is apparent in paraspinal region. Low-attenuation nodes with or without rim enhancement are typical of tuberculosis.

boy. This child first presented

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Fig.

9.-Anterior mediastinal T-cell lymphoma in 6.5-year-old boy. A, Chest radiograph shows large anterior mediastinal mass causing

fullness and lobulation In right paratracheal region are important slightly to right. Left apical chest tube is present. B, Contrast-enhanced

CT scan of chest

shows

large solid,

opaque left hemithorax with small left apical pleural stripe (arrowheads). Slight imaging findings suggesting that mass arose from mediastinum. Trachea Is shifted

homogeneous,

diffusely

and mildly

enhancing

mass

(M) originating

in anterior

mediastinum

and extending predominantly

into left hemithorax. Right and left main bronchi (arrows) and mediastinum are compressed posteriorly by mass effect. Chest tube is present in left side of chest. There Is no evidence of calcifications, fat, or cysts within mass to suggest possibility of germ cell tumor or ten-

atoma. Lymphoma, thymic infiltration from leukemia, and thymic hyperplasia may resemble each other at imaging and are distinguished by histopathology. S = superior vena cava, A = ascending aorta, D descending aorta, P = main pulmonary artery, L = left pulmonary artery, R = right pulmonary artery. =

Fig. 10.-Neuroblastoma

with Intraforaminal

extension In 2.5-year-old girl. A, Anteroposterlor chest radiograph shows large posterior mediastinal mass (white arrows) in

left hemithorax

with multiple punctate

calcif ice-

tions and associated shift of trachea (arrowheads) and mediastinum to right. Left lower lobe (solid black arrows) is collapsed because of compres-

sion of left lower lobe bronchus. Left sixth through ninth posterior ribs are splayed, and posterior medial sixth and seventh ribs are mildly eroded (open black arrows), indicating location of mass

in posterior mediastinum. B, Contrast-enhanced CT scan of chest shows homogeneous posterior medlastinal mass con-

taming

calcifications (helpful distinguishing feature) displacing aorta (A) and left bronchus (arrowheads) anteriorly. Posterior medlastinal

mass with calcificatlons is typical of neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, which are primarily differentiated by patient age and histopathologic findings. C, Coronal Ti-weighted (698/21 [TR/TE])

MR image shows large left-sided posterior mediastinal mass extending into three intervertebral foramina (arrows), distinguishing feature of neurogenic tumors.

932

ABLIN

ET

AL.

AJR:165,

October

1995

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Fig. ii.-Ganglloneuroblastoma

of posterior mediastinum in 2-year-old girl. A, Anteroposterlor chest radiograph shows nearly completely opaque right hemithorax with shift of trachea (white arrows) and mediastinum to left and assodated pleural fluid. Component of mass extends to left of midline in lower thoracic region (black arrows), and lower posterior right seventh through ninth ribs are eroded and thinned (arrowheads), Indicating location of mass in posterior mediastinum. B, Coronal Ti-weighted (600/20 [TRITE]) MR Image shows large right-sided intrathoracic mass extending to left of midline and displacing descending aorta to left (arrowheads). C and D, Axial contrast-enhanced Ti-weighted (800/20) MR Images show enhancement of intraspinal component of mass (arrows) extending through two thoracic neural foramina into spinal canal, indicating neurogenic origin of mass. This characteristic was seen from T6-Ti0 levels. Neuroblastoma, gangiioneuroblastoma, and ganglioneuroma are similar In appearance on MR images and are distinguished by histopathologic findings.

A .

.

.-.

.

,#{149}if

-..

II

A

Fig. oma

in

12.-Anterior 10-year-old

mediastinal lymphangigirl with partially opaque

right hemithorax. A, Contrast-enhanced CT scan of shows inhomogeneousiy enhancing mass ing from anterior medlastinum. Superior cave (5), ascending aorta (A), descending (D), pulmonary artery (P), and right main chus (B) are displaced posteriorly by mass. B, Contrast-enhanced CT scan of

shows

,;:L

mass

extending

Inferiorly,

filling

chest arisvena aorta bronchest

right

hemithorax and containing fluid-filled cysts with enhancing septa (arrows), key distinguishing features of lymphangioma. Right lung Is collapsed posteriorly because of compressed right bronchus and mass effect. Presence of cysts is helpful in excluding lymphoma and leukemia as cause of anterior mediastinal mass. Lack of associated fat and caicifications is helpful in excluding teratoma and germ cell tumor.

LARGE

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AJR:165, October 1995

INTRATHORACIC

TUMORS

A

Fig. 13.-Posterior

mediastinal

lymphangioma

bilateral partial opaque hemithoraces A,

Axial sonogram of

right

lower

resembling hemithorax

IN CHILDREN

933

B

In 5-year-old

girl with

chest

radiograph

showing

large bilateral pleural effusions. shows

multiloculated

fluid-filled

cystic

mass

con-

taming mobile septa (arrows) within fluid, characteristic of lymphangioma. H = heart, S = spine, P = posterior, A = anterior, L = lateral. B, Contrast-enhanced CT scan of chest shows fluid-filled posterior mediastinal mass characteristic of lymphangioma

extending

between

aorta

(A) and inferior

vena

cave (I) and having

significant

mass effect on mediastlnum.

Esophagus (E) is deviated anteriorly and to left, Indicating posterior origin of mass. Septa (arrows) are present within mass. C, Coronal Ti-weighted (750/25 (TRITE]) MR image shows high-signal-Intensity mass (M) in right and left posterior mediastinum, extending anteriorly and superiorly to splay carina (arrowheads) and to displace lungs (L) superiorly. Overall extent of mass is best shown on this MR Image.

C

nal tumors [6, 9]. There are two age peaks for germ cell tumors: approximately at age 2 years and later during adolescence. Giant thymomas are extremely rare [9].

Middle

Mediastinum

The most common large intrathonacic masses of the middie mediastinum are enlarged lymph nodes that are attnibutable to lymphoma on leukemia and that usually simultaneously involve the anterior mediastinum. Middle mediastinal adenopathy attributable to infection, inflammation, on metastatic disease is common and rarely massive [9]. Adenopathy associated with consolidating pneumonia and/on empyema may mimic a lange intnathonacic tumor (Fig. 8). Bronchopulmonany foregut malformations, including mediastinal bnonchogenic cysts and esophageal duplication cysts, are commonly found in the middle mediastinum, but they are small and are not usually manifested by an opaque hemithonax. Their cystic nature is readily identified on sonograms and/on CT scans [5, 6, 9].

Posterior

Mediastinum

The majority of large intrathoracic masses of the postenor mediastinum are neurogenic tumors arising from the sympathetic chain, especially neunoblastomas (Fig. 10), ganglioneuroblastomas (Fig. 11 ), and ganglioneuromas, in descending order of frequency. Neunoblastomas usually occur in children less than 5 years old, ganglioneunoblastomas usually occur in children between 5 and 10 years old, and ganglioneuromas usually occur in children more than 10 years old [9]. Key imaging features include paraspmnal bocation

of the

mass;

presence

of calcifications

within

the

mass

(best seen on unenhanced CT scans); thinning, splaying, and erosion of the posterior nibs; neural fonaminal enlargement; and intnafonaminal or intraspinal extension on CT scans on MR images. MR imaging is superior to CT in showing intrafomammal on intraspinal extension of the mass (Figs. bC, 11C, and 11 D) and in showing chest wall invasion or bone marrow involvement [9]. Posterior mediastinal neurentenic cysts are associated with vertebral anomalies on scoliosis and may communicate

with

the gastrointestinal

tract

[5, 6, 9].

ABLIN

934

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All Compartments Massive lymphangiomas, benign tumors resulting from malformation of the lymphatic system isolated to the mediastinum, are rare but may occur in the anterior (Fig. 12), middie, on posterior mediastinum, in decreasing order of frequency; even more namely they may be bilateral [5, 9] (Fig. 13). Their cystic nature, a differentiating feature, is readily identified on sonognams, CT scans, and/on MR images (Figs. 12B and 13). Although lymphangiomas are benign and are cured with complete excision, they may result in serious mombidity and mortality when they infiltrate and/on compress vital structures. Rhabdomyosancomas and other soft-tissue samcomas may namely anise from the mediastinum (Fig. 4), as mentioned earlier.

Diseases

That

Simulate

Large

Intrathoracic

Masses

Other diseases that cause an opaque hemithomax and that could be confused with large intnathonacic masses are large fluid-filled diaphnagmatic hernias, endobronchial lesions (i.e., bronchial adenoma) of a main bronchus with collapse on

ET AL.

AJR:165, October

pneumonia, or massive with associated pleural

candiomegaly on pemicandial fluid on atelectasis.

1995

effusion

REFERENCES 1 . Cumming WA, Sabbah R. Large Assoc Radiol J 1985:36:234-237

unilateral

chest

tumors

in children.

Can

2. Franken EA, Smith JA, Smith WL. Tumors of the chest wall in infants and children.

Pediatr

3. Winer-Muram tive

Radioli977;6:i

HT, Kauffman

neuroectodermal

tumors

3-18

WM, Gronemeyer of the chest

SA, Jennings

wall (Askin

tumors):

5G. PrimiCT and MR

findings. AJR 1993:161:265-268 4, Crist WM, Raney RB, Newton W, Lawrence Intrathoracic soft tissue sarcomas in children.

MA.

5. Hernanz-Schulman

Clin

North

M. Cysts and cystlike

W, TeffI M, Foulkes Cancer i982;50:598-604 lesions of the lung. Radiol

Am 1993:31:631-649

6. Kapoor R, Saha MM. Sonographic

evaluation

Australas Radiol 1991:35:233-236 7. Laufer L, Cohen Z, Mares AJ, Maor E, Hirsch granuloma. Pediatr Radiol 1990:20:289-290

8. Domizio

P. Liesner RJ, Dicks-Mireaux

chymoma associated with and review of the literature.

of chest masses in children. M. Pulmonary

C, Risdon RA. Malignant

a congenital lung cyst in a child: Pediatr Pathol 1990:10:785-797

9. Meza MP, Benson M, Slovis TL. Imaging of mediastinal dren.

Radiol

Clin North

Am 1993;31

plasma-cell

:583-604

case

mesenreport

masses in chil-