大짧放射線뽑쩔會끓‘ 第 26 卷 第 4 號 pp. 735 -742. 1990 Journal of Korean Radiological Society. 26(4) 735 - 742. 1990

Malignant vs. Benign Pleural Lesion: CT Findings

Sung-Jin Kim, M.D. , Jung-Gi 1m, M.D. , K iI S un Park, M.D. , Hak Soo Kim , M.D. , Man Chung Han , M.D.

Department o[ RadioJogy' SeouJ NationaJ Un i versity. CoJlege o[ Medicine

〈국문초록〉

악성 흉막 질환과 양성 흉막 질환으I CT 소견

서 울 이| 학교 의파내혁 l앙사선괴혁교실

김 성 진·임 정 기 ·박 길 선·김 학수·한만청

흉막 질환은 염증성 혹은 악성 종양동의 다양한 원인에 의해서 야기되며 이러한 다양한 질환의

감별은 사실상 매우 어렵다. 그러 나 CT 스캔의 영상 행상력이 좋아지면서 흉막병변의 해부학적

충에 따른 변화를 분석함이 가능하게 되였다. 연자퉁은 고해상 CT를 포함한 CT 스캔 영상에서

질환별 소견의 차이를 분석하여 그 갇별 점을 찾고자 하였다.

대상은 남자 49명 여자 1 9명 총 68명 이었으며 연령 분포는 4세에서 78세까지로 평균 연령은 49.

4세였다. 질환의 종류는 농흉 ( n=29 ) . 악성 흉막질환( n =2 1 ) ， 섬유흉 ( n=9 ) 및 자유 흉막 상출

액 (n=8 ) 이 였 다. CT 스캔상 악성 흉막 질환과 농흉의 전 예에서 벽측 흉막의 비후와 조영 증강이

있었고 섬유흉의 경우에서는 흉막 외 극에 지방동을 포함하는 조직의 축적 이 관찰되었다. 악성 흉

막 병변의 가장 특정적인 소견은 흉막의 소결절성 종괴와 결절성의 전흉막비후(nodular mass

and nodular pleural rind ; 17 / 21, 13 / 21) 흉막 비 후의 단절 (interruption of pleural thickening ;

14 / 21). 공격적 양상의 흉막 삼출액 ( aggress ive fluid collection ; 1 4 / 2 1 ) 과 종격 흉막의 침습

(mediastinal pleural involvement ; 20 / 2 1 ) 이 였 다. 농흉에서는 비후된 흉악이 전장에 걸쳐 서 평

활하고 두께가 일정하였으며 (25/3이 벽측 흉막과 흉내근막 사이인 흉막 외 극에 조직축적

(extrapleural tissue accumulation ; 1 8 / 30 ) 이 있는것이 가장 흔한 CT 소견이 었다.

이상의 결과에서 CT 스캔은 양성과 악성 흉막 질환의 감별에 상당히 도움이 될것이라고 사료

된다.

Index Words: Pleura. CT . 66. 1211 Pleura. f1uid. 66.76 Pleura. infection . 66.20 Pleura. Neoplasm. 66.32

Introduction or metastatic maJignancies . Although th e pro­

gress in the development of a real t ime scanners

has expanded th e appJication of ultrasonography

in pleur외 pathology. pleural lesion s are difficult

to differentiate u s ing coventional imaging me­

thods 1.21. Especialiy plural effu s ions associated

with neoplasms are caused by several different

Pleural les ions are caused by a variety of dise­

ases, including in f1ammatory diseases. primary

이 논문은 1990년 5월 1 일 접수하여 1 990년 5월 28일에

채택되었음

Received May 1. accepted May 28. 1990

m …

- 大韓放射線醫學會註 第 26 卷 第 4 號 1990 -

mechanisms : direct involvement of the pleural

surfaces by tumor , lymphatic or venous obstruc

tion , endobronchial obstruction with atelectasis ,

postobstructive pneumonitis with a parapne­

umonic effusion and severe hypoproteinemia.

These latter four etiologies account for a large

percentage of the negative cytologic and pleural

biopsy findings in these patients3l .

Because of the improvement of resolution po­

wer of CT scan , it becomes possible to analyze

the changes of pleural space , layer by layer. 50,

CT scan is well suitable for detection and char­

aterization of pleural disaese by analyzing the

changes of anatomical layers. But the appea­

rences of pleural disease at CT scan have not

been extensively described and are less well

known. To identify the reasonable criteria in dif­

ferential diagnosis of pleural diseases , we revie­

wed the CT scans of 68 patients with docu­

mented pleural diseases.

Materials and Methods

We reviewed chest CT of 68 patients showing

evidence of pleural pathology or pleural fluid at

chest radiography without regard to any specific

diagnosis between Januarγ 1988 and February

1990. This study group consisted of 19 female

patients and 49 male patients ranging in age

from 4 to 78 years(mean age , 49.4 years). 29 pa­

tients had empyema, 21 patients had pleur머

malignancy such as mesothelioma (n= 3 ) or pleu­

ral metastasis associated with extrapleural pri-

Table 1. Diagnostic Methods

Pleural Biopsy Cytology

Malignancy 8 14 Empyema 7 o Fibrothorax 0 0 Free Fluid 0 0

Total 15 14

- 736

mary malignancies (n= 18) , 10 patients had fib­

rothorax , and 8 patients had free pleural effu­

sion without other pleural pathology.

Diagnoses were confirmed by operation , pleu­

ral biopsy , cytology of pleural fluid , bacteriolo잉r，

or clinical history and course(Table 1). In mali­

gnant pleural lesions , the diagnosis was con­

firmed by pleur외 biopsy (n=8 ), cytology of pleu­

ral fluid (n= 14 ), and operation (n= I) . The di­

agnosis of empyema was based on pleur떠 biopsy

(n=7 ), operation (n= 6 ), bacteriolo잉r of pleural

fluid and sputum (n= 12 ), and compatible clinic­

al course and follow up radiography after treat­

ment (n=5 ).

61 patients were scanned on a GE 9800 scan­

ner(Geberak Electric Medical 5ystem , Milwau­

kee). In the remaining patients scans were done

on Tosiba 80-A (n=4 ), Siemens Somatom DRG

(n=2 ), and Shimadzu SCT 2000 T-ll (n= 1). In

48 patients , contiquous 1 cm thick CT scan was

obtained from the apex to the base of the lung.

In 12 patients , high resolution CT scan was per­

formed with a GE 9800 CT scanner(l .5 mm col­

limation, 140 KVp , 170 rr머， 3 seconds). Both

methods were obtained in 8 patients. An intra­

venous bolus of contrast dye(Telebrix 30 Meglu­

mine , 2 m l/Kg) was given to all patients

CT scans were evaluated to assess the fol­

lowing signs; 1) nodular pleural rind , 2) no­

dular mass , 3) interruption of pleural thicke­

ning, 4) aggressive fluid collection, 5) medias­

tinal pleural involvement , and 6) tissue char­

ateristics of extrapleural space. We defined the

Clinical B없ac따teriology Operation Course

0 l 0 12 6 5 0 9 O o 8

12 8 22

- Sung-Jin Kim. et al. Malignant vs. Benign Pleural Les ion ' CT Findi ngs

interruption of pleural thickening as focal dis

continui앙 of diffuse pleural thickening‘ and the

aggressive f1uid collection as mutiloculated f1uid

collection which has abrupt bulging contoured

tense f1uid collection. acute angle between 10-

culated f1uid and pleura. and extensive atelec­

tasis comparing with the amount of f1uid. Ple

ural thickening was thought to be presen t, if

there was visible soft tissue stripe between rib

and lung. Because visceral pleural involvement

could not definitely evaluate due to associated

atelectasis. we evaluated parietal pleura only. CT

density of exrtapleural tissue was compared with

adjacent fat. muscle. and f1uid

Results

AlI cases of the malignant pleural lesion and

empyema showed pleural effusion. thickened

parietal pleura and enhancement. But in the

cases of free f1uid. pleural thickening and con­

trast enhancement was not identified . The cases

of fibrothorax revealed extrapleural fat accumu­

lation and none of these showed pleural f1uid­

(Fig. 1).

Malignant pleural lesions

The most charateristic CT features of malig­

nant pleural lesions included nodular mass at­

tached to parietal pleura( 17/21). nodular pleur외

rind( 13/21 ), interruption of pleural thicken-

Table 2. CT Findings in Pleural Lesions

Fig. 1. This 35-year old man had left sided tuber culous pleurisy 23 years earlier. CT scan reveals a thickened pleura and calcification without f1uid col­lectin. Fatty tissue(arrow) is seen between the calci­fied pleura and inner chest wal1 .

ing(l4/2 1), aggressive f1uid collection(l 4 /21 )

and mediastinal pleural involvement(20/21). Ex

trapleural tissue ranged in density from fat to

muscle was demonstrated on CT in only 5 pa­

tients(Table 2).

Empyema

The most common findings were diffuse. uni­

form and smooth surfaced pleural thickening

Findings Malignancy( %) Empyema(%) n=21 n=29

14(66.7) O (0)

17(8 1.0) 5(17.2)

13(6 1.9) 1 (3 .4)

14(66.7) 2 (6.9)

20(95.2 ) 6(20.7)

5(23 .8) 18(62.1)

lnterruption of Pleural Thickening

Nodular Mass

n

e 뼈 뼈

… α ·

밍 야

“ 띠 m

않

따 ’ m mn

T

뻐 Jm

뻐 때

빼 앉 뼈 빼

M… 며 M

E

η

- 大障放射線뚫學會픔 : 第 26 卷 第 4 號 1990 -

and contrast enhancemen t. which were present Table 3. Analysis of Extrapleural Tissue

in all cases(Fig. 2). Nodular pleural thickening

was a rare finding of empyema and seen in only

5 patients with tuberculous empyema(Fig. 3). In

contrast to the malignant pleur외 lesions , aggres­

sive f1uid collection (n=2) , nodular pleur려 rind

(n= 1). nodular mass (n=5). intertuption of

pleural thickening (n=O). and mediastinal ple­

ural involvement (n=6) were unusua1 fin-

dings(Table 3). Another characteristic finding of between the chest wall and pleura, which was

empyema was extrapleural tissue accumulation observed in 18 patients. This was a more pro-

nounced feature in tuberculous empyema than

in nontuberculous ones(Fig. 4). The densities of

the accumulated tissue were ranged from fat to

muscle , but mainly were that of fat(1 5/18).

Fig. 2. CT scan in a patient with a tuberculous em­pyema confirmed by operation shows diffuse , uni­form thickening and contrast enhancement of pleura.

Fig. 3. 1.5 mm collimation scan reveals nodular pleural thickening in a patient with a tuberculous empyema. But, note the fatty tissue beneath the thickened pleura(arrow)

Density Malignancy( %) Empyema(%) n=21 n = 29

Fluid 2(9.5) 4(13.8)

Muscle 1(4.8) O( 0)

Fat 2(9.5) 15(5 1. 7)

Total 5(23.8) 19(5 1.5)

Sensitivity and Specificity

The sensitivity and specificity of each finding

for malignant pleural diseases were as follow;

77.3 % and 84.5 % for nodular mass , 92.9 % and

76.5 % for nodular pleural rind , 100 % and 79.4

% for interruption of pleur외 thickening, 87.5 %

and 78.1 % for aggressive fluid collection , 74'.1 %

Fig. 4. 1.5 mm collimation scan with a tuber­culous empyema reveals a linear fatty tissue(arrow) beneath the smooth thickened pleura with a len­ticular fluid collection. These are characteristic fin­dings of empyema(especially, tuberculous empue­ma)

m

ω

- Su ng- Ji n Kim , et al. : rvlalignant vs . Benign Pleural LeS10n : CT Fi ndi ngs-

and 95 , 5 % for mediastinal pleural involvement on its luminal margin7.8l, The explanations are

and 78 , 3 % and 64 , 0 % for extrapleural tissue as followings ‘ as an empyema progresses. a fib-

accumulation. respectively , The most sensitive rin peel coats the visceral and pariet외 pleural

and specific finding were interruption of pleural surfaces , This peel organizes with ingrowth of

thickening and mediastinl pleural involvemen t. capillaries and fibroblasts as early as 7 days after

respectively. the onset of disease. forming the split pleura

sign representing visualization of smooth thic-

Discussion kened. separated visceral and parietal pleural

surfaces71. In the malignant pleur외 effusion. pleu

r외 f1uid accumulation is attributed to inceased Normally the pleura and endothoracic fascia

pass internal to the ribs. But they are not visible

in this location on conventional and high resolu­

tion CT ‘ Therefore. a soft tissue stripe demons­

trated internal to the ribs on conventional CT

can be used to diagnose pleural thickening or

effusion41 . A number of articles have discribed

the CT findings of pleural lesions. including

pleural tuberculosis5,61. empyema7

,81. mesothe­

lioma91 . and pleural manifestation of

lymphoma 1ol . But to our knowledge. no large

series except one have compared benign and

malignant pleural lesions focusing to differential

diagnosis , Solanen et a l. described that high

contrast enhancement of the pleura was typical

finding of active pleural disease: this. in com­

bination with an infiltrative nature of lesion. was

indicative of malignancy. but benign infectious

process did not show infiltration ll l. Our results

were consistent with observation of Solanen et

a l.

-Nodular mass and nodular pleural rind ;

It is well documented that mesothelioma has

extensive. lobular thickened irregular masses in

volving 외1 pleural surfaces including the medias

tinum9 , 121. A similar configuration can be en­

countered in advanced metastatic carcinoma in­

volving the pleura91 . And pleural based mass may

be encountered in various malignant diseases

such as lymphoma. metastasis and thymo

ma l 10 , 141 But empyema shows wall charateris

tics that is distinctly thin. uniform and smooth

net filtration of pleural f1uid though serous mem­

branes irritated by tumor implants l31.

In our series. nodular mass and nodular pleu­

r려 rind was observed in 81.0 % and 61.9 % for

malignant pleur외 lesions. respectively(Fig , 5).

These finding. however. were observed each in 5

and patients with tuberculous empyema.

Therefore these findings may be helpful in the

differential diagnosis between malignant and be­

nign pleural lesions.

-Interruption of pleural thickening;

The interruption of pleural thickening was ob­

seπed in 14 cases of malignant pleural le­

sions(Fig , 6). But this finding was not identified

in the cases of empyema. This finding is the

most sensitive finding of malignancy in our se

ries. but has not been discribed ye t. We consider

that this finding may be caused by uneven dis­

tribution and growth of metastatic tumor im­

plants and may be the earliest finding of metas­

tatic pleural lesion that can be detected on CT.

-Aggressive fluid collection ;

Atypical f1uid collection in the pleural space is

well documented finding in the previously dise

ased pleura such as tuberculosis. But the ag

gressive f1uid collection was more common in the

malignant than benign pleural lesions(Fig. 7) , In­

terestingly. 4 cases of these showed nodular

mass or pleur외 thickening abutting the f1uid col­

lection(Fig. 8). lt is the possible explanation for

재

/、템 Ij'z 끼 f쐐감섹혐;t : 第 26 잔 第 ι1 꽤 i 99u

this finding that massive fluid collection between

visceral and parietal pleura is loculated by pleu­

ral adhesion which is produced by metastatic tu­

mor implants. In contrast , this finding is un­

usual in the empyema. Therefore , this may be

another helpful finding to differentiate malig

nant from benign pleural lesion.

-Mediastinal pleural involvement;

The mediastinal p leura is especially difficult to

evaluate on conventional imaging modalities.

But mediastinal pleural pathology and other me-

diastinal lesions are well demonstrated by CT a

h Fig. 5. a. CT scan in a patient with a metastatic adenocarcinoma shows uneven thickening and no­duar mass(a rrow) . b. CT scan reveals nodular pleural thickening in thc entire pleura including mediast inal and parietal pleura. This patient was confirmed to metastatic adenocarcinima by pleural biopsy

b Fig. 6. a ‘ b : CT scan in a same patient with metas­tatic adenocarcinoma show discontinuity of pleural thickening. interruption(arrow). It may be the ear­liest finding of metastatic lesion

Fig. 7. CT scan shows multiple loculated fluid col­lection with bulging contour and acute angle bet­ween loculated fluid and pleura(arrow).

때

- Sung-J in Kim, et al. Malignant vs . Benign Pleural Les ion CT F indings

Fig. 8. CT scan in a patient with metastatic adeno carcinoma shows enhancing nodular mass abutting the f1uid collection(arrow)

scan 11J . Mediastinal p leural involvement in the

mesothelioma has been reported in other arti­

cJes9, 12J. But. to our knowledge . only one paper

discribed mediastinal pleural involvement regar­

ding the differentiation of malignant from be­

nign pleural lesion 15J .

In our s eries . mediastinal pleural invovement

such as loculated f1uid collection. nodular mass

and nod ula r pleural thickening was relatively

common in malignant pleur머 in volvementlFig.

9-AJ. but even loculated pleur혀 effusion was a

rare finding in benign lesion. 6 of our benign

cases showed mediastinal pleural involvement.

and 5 cases of these were tuberculous empye­

ma(Fig. 9 -B) . Al though mediastinal pleural in­

volvement is the most specific finding of mali­

gnancy. it cannot distinctly excJude the possibili­

ty of benign lesion. especially tuberculous empye­

ma. ConcJusively. this findidng may be helpful in

the diagnosis of malignant p leural lesion.

-Extrapleural tissue accumulation ;

Normally. the layer of fatty connective tissue is

located b etween the parie tal pleu ra and endoth o­

racic fascia. This layer is better demonstrated on

h igh resolution CT than on conventional CT. In

most of normal su이ects. however. the intercostal

fat layer is not cJearly seen in all locations4J . In

patients with chronic pleural disease. the CT de­

nsity of extrapleur외 tissue in compa rision with

that of adjacent organ or fluid was ranged from

fat to muscJe density. But. in comparision to

malignancy or nontuberculous empyema. the

b Fig. 9. a. CT scan in a patient with metastatic ade nocarcinoma shows f1uid collection in the media­stinal pleura(arrow) , Also noted nodular pleural th ickenine: in the parietal pleura. b , CT scan shows left sided mediastinal pleural thickening(arrow) and nodular pleural rind , Also note pleural thickening on the righ t. This 4 year old girl was ccnfi rmed to tl . Jerculous empyema by pleu­ral biopsy

- 741 -

- 大韓放射線醫學會註、 第 26 卷 第 4 號 1990 -

5. Hulnick DH. Naidich DP. McCauley DI. Pleural

tuberculosis eValuated by computed tomo­

graphy. Radiology 1983; 149 : 759-765

6. Schimitt WGH. Hubener KH. Rucker HC. Pleu­

ral calcification with persistent effusion. Radio­

logy 1983; 149 : 633-638

7. Stark DD. Federle MP. Goodman PC. Podras애

AE. Webb WR. Differentiating lung abscess and

empyema. AJR 1983; 141 : 163-167

8. Baber CE. Hedlung LW. Oddson TA. Putman

CE. Differentiatlng empyemas and peripher떠

pulmonary abscesses. Radiology 1980; 135 :

755-758

9. Rabinowitz JG. Efremidis SC. Chben B et 외.A

comparatine study of mesothelioma and asbes­

tosis using computed tomography and conven­

tional chest radiography. Radiology 1982 ; 144 :

453-460

10. Shuman LS. Llbishitz HI. Solid pleural mani­

festation of lymphoma. AJR 1984; 142: 269-

273

11. Salonen O. Kivisaari L. Stadertsklold-Norden­

stam CG. Somer K. Mattson K. Tammilehto L

Computed tomography of pleural lesion with

speCl허 reference to the mediastinal pleura. Acta

Radiol 1986 ; 27 : 527-531

12. Kreel L. Computed tomography of the lung and

pleura. Semin Rentgenol 1978; 13 : 213-225

1. Steinberg lN. Erwin BC. Metastasls to the 13. Leff AL. Hopewell PC. Costello J. Pleural effu-

pleura: Sonographic detectlon. JCU 1987; 15: sion from malignancy. Ann Intern Med 1978;

276-279 88 : 532-537

2. Martinez OC. Serrano BV. Romero RR. Real-ti- 14. Kim HJ. 1m JG. Lee JH. CT manifestation of

me ultrasound evaluation of tuberculous pleur외 thymomas : benign versus invasive thymomas.

effusions. JCU 1989; 17 : 407-410 The journal of the korean radiological society

3. Chernow B. Sahn SA. Carcinomatous involve- 1988; 24 : 775-781

ment of the pleura an analysis of 96 patlents. 15. Leung AN. Muller NL. Miller RR. Differential di-

Am J Med 1977; 63 : 695-702 agnosis of diffuse pleural disease with CT

4. 1m JG. Webb WR. Rosen A. Gamsu G. Costal Radiology RSNA ’89 scientiflc program 1989;

pleura : Appearances at high resolution CT. 173(p) : 139

Radiolo밍， 1989; 171 : 125-131

cases of tuberculous empyema showed mainly fat

density. We believe that extrapleural fat accumul

ation may indicate rather a chronic process of

the diseases and fluid accumulation a more

acute process . Therefore. the extrapleural fat ac­

cumulation looks to represent rather a benign

than a malignant disease.

Conclusion

Pleural thickening and enhancement indicate

active pleural lesion either benign or m외ignant.

Nodular mass. nodular pleur외 rind . interruption

of pleural thickening. aggressive fluid collection

and mediastinal pleural involvement are chara­

terestic findings of malignant pleural involve­

ment are charaterestic findings of malignant le­

sion. In contrast. diffuse. smooth and uniform

pleural thickening with or without extrapleural

fat accumulation indicated benign pleur외 lesion.

8ased on these findings presented in this report.

CT is thought to be helpful to differentiate mali-

gnant from benign pleur외 lesions.

REFERENCES

… κ