CT and MR imaging of abdominal liposarcoma

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829

CT and MR Imaging Li posarcoma

Tonsok Kim1’2 Murakami1 Hiromichi 0i2 Kyo Tsuda1 Masaki Matsushita2 Kaname Tomoda1 Hanuki Fukuda3 Hironobu Nakamuna1

Takamichi

of Abdominal

OBJECTIVE. CT and MR images were reviewed to correlate the histologic subtypes of abdominal liposarcoma wIth the radiologic findings. SUBJECTS AND METHODS. Ten patients with liposarcoma who underwent CT or MR imaging before surgery were included in this study. CT and MR imaging findings for these patients were compared retrospectively with histologic findings. RESULTS. Major histologic subtypes found in our group of patients were five welldifferentiated, three myxoid, one pleomorphic, and one round-cell liposarcomas. The well-differentiated subtype consisted of lipoma-like and/or sclerosing components. The predominant attenuation and signal intensity characteristics of the lipoma-like components on CT and MR images resembled those of fat, whereas the predominant attenuation

and

signal

intensity

characteristics

of the

sclerosing

components

resem-

bled those of muscle. The myxoid subtype showed, on unenhanced images, predominant attenuation and signal intensity characteristics that resembled those of water; on contrast-enhanced images, this subtype showed gradual reticular enhancement. The appearance of the round-cell and pleomorphic subtypes was that of heterogeneous, nonfatty tumors. Their characteristics were indistinguishable from those of other malignant soft-tissue masses. CONCLUSION. Each histologic subtype of abdominal Ilposarcoma showed different CT attenuation or MR imaging signal Intensity characteristics. A clear understanding of these findings should prove helpful in the diagnosis of liposarcoma. AJR

1996;166:829-833

Liposancoma is a malignant tumor of mesenchymal origin. Liposarcoma is one of the most common primary neoplasms in the retnopenitoneum, whereas primary mesenteric and primary penitoneal liposancomas are rare [i-3]. It is often difficult to use imaging findings to diagnose abdominal liposancoma when it lacks a fat component. Histologically, liposarcomas are classified as well-differentiated, myxoid, pleomonphic,

Received September 1 5, 1995; accepted after revision November 22, 1995. 1 Department of Radiology, Osaka University Medical School, 2-2 Yamadaoka, Suita City, Osaka 565, Japan. Address correspondence to T. Kim. 2 Department of Radiology, Osaka Teishin Hospital, Osaka

City, Osaka

3Department Medical

School,

of Suita

0361-803X/96/1664-829 © American Roentgen

543, Japan.

Pathology,

Osaka

City, Osaka Ray Society

University

565, Japan.

and

round-cell

subtypes

[4].

In addition,

well-differentiated

tumors

are

subdi-

vided into four types: lipoma like, sclerosing, inflammatory, and dediffenentiated. Prognosis for patients with liposarcoma varies on the basis of the histologic subtype [1 5, 6]. Well-differentiated liposancoma is considered a low-grade malignancy; myxoid liposarcoma is considered an intermediate-grade malignancy; and pleomorphic and round-cell liposarcomas are considered high-grade malignancies with high rates of local recurrence and metastasis. Reports have correlated imaging findings and histologic subtypes of liposarcoma in the extremities [5, 7] but, to our knowledge, no such report exists for abdominal liposarcoma. For this study, we retrospectively reviewed and compared CT and MR imaging findings for abdominal liposancomas with pathologic findings for resected specimens to clearly identify the imaging appearance of each specific histologic subtype of abdominal liposarcoma. ,


Subjects

and

tion) or fast low-angie

Methods

Ten patients with liposarcoma in the abdominal region who underwent CT examination before resection between i 990 and 1995 were included in this study (Table 1). Seven of the 10 patients also underwent MR imaging examination before surgery. All CT and MR imaging examinations were performed within 1 month of surgery. All patients were women and were 43-77 years old (mean, 55 years old). The primary sites of the liposarcomas were the retnoperitoneum in seven patients, the mesentery in one, the mesosigmoid in one, and the peritoneum in one. The liposarcomas were histologically identified

by complete The

AJR:166, April 1996

KIM ETAL.

830

resections

liposarcomas

in nine patients

were

classified

into

and by open biopsy in one. histologic

subtypes

on the

basis of the most aggressive cellular component of the tumor. CT examination was performed with a Somatom Plus scanner (Siemens,

Erlangen,

tnic-Yokogawa

Germany),

Medical,

Tokyo,

a Quantex Japan),

scanner

(General

or a High-Speed

mmol

of

gadopentetate

Japan)

dimeglumine

(Magnevist;

per kg of body weight.

Nihon

Schening,

MR imaging

before and after administration of gadopentetate dimeglumine was performed on two of the four patients. The gradient-echo MR images

were obtained

with fast multiplanar

tion in the steady

TABLE

Patient

1

state

1 : Abdominal

spoiled gradient-recalled [TRITE];

Liposarcoma

Age (Yr)

65

(160/2.5

Primary

flip angle,

[TRITE];

flip angle,

ated for the six trast-enhanced Predominant sified into four images: group

patients who underwent both unenhanced and conCT imaging. MR signal intensity characteristics of tumors were clasgroups on the basis of both Ti- and T2-weighted A showed signal intensity less than that of muscle;

B showed

signal

intensity

equal

to that of muscle;

group

acquisi-

60#{176}; one excita-

fat; and group D showed fat. Tumor enhancement

Mesosigmoid

Histologic Subtype Seen Majority of Patients

Well differentiated

spin-echo

images also were evaluated for the four patients who both unenhanced and contrast-enhanced MR imaging.

MR

underwent Results

Histologic

Subtypes

In this study, the histologic subtypes of the iO liposarcomas were as follows: five well differentiated (either lipoma like or lipoma like and sclerosing), three myxoid, one pleomorphic, and one round cell. Liposancomas of six patients were of only one histologic subtype, whereas those of the other four patients included minor components of another histologic subtype (Table i). Of the five well-differentiated liposarcomas, one was a lipoma-like subtype with calcifications, three were lipoma-like

subtypes

with

sclerosing

components,

and

was a lipoma-like subtype with a myxoid subtype component. Of the three myxoid liposarcomas, solely myxoid, one included a sclerosing subtype

in

Images Obtained

Histologic Subtype Seen in Minority of Patients

CT

54

Aetroperitoneum

Well differentiated

MR

(lipoma

UE and CE

Ti- and T2-WSEI

(lipoma

UE and CE

Not obtained

(lipoma

CE

Not obtained

UEandCE

Ti-, 12-, and CETi-WSE1

CE

Ti-and

CE

Ti-,

like and sclerosing)

3

65

Retropenitoneum

Well differentiated like and sclerosing)

4

77

Retropenitoneum

Well differentiated

(lipoma

5

46

Mesentery

6

47

Penitoneum

like) Well differentiated (lipoma like and sclerosing) Myxoid

7

43

Retropenitoneum

Myxoid

Myxoid

Well differentiated (sclerosing) Well differentiated

(lipoma

UE and

CE

Ti-,

like)

8

63

Aetroperitoneum

Myxoid

9

43

Retropenitoneum

Pleomorphic

10

49

Retropenitoneum

Round

Note-All

patients

T2-WSEI 12-,

and

CET1-WSEI

12-,

and

CE Ti-WSEI

and gradient

were

women.

UE

=

unenhanced,

cell

CE

Ti-, T2-, and CETi-WSEI

CE

Ti-and

UE and =

contrast enhanced,

T1-WSEI

=

Ti-weighted

echo

UEandCE

and gradient Well differentiated (lipoma like and sclerosing)

CE

spin echo, T2-WSEI

echo

T2-WSEI

Not obtained =

T2-weighted

one

as a minor one was as a minor

like)

2

C

signal intensity equal to or greaterthan that of patterns on contrast-enhanced Ti -weighted

Patients

Site

60#{176};

showed signal intensity greater than that of muscle but less than that of

Advantage

Gradient-echo

(150/4

group 1 showed attenuation approximately equal to that of fat; group 2 showed attenuation greater than that of fat but less than that of muscle; and group 3 showed attenuation equal to or greater than that of muscle. Tumor enhancement patterns also were evalu-

group

Elec-

scanner (General Electric Medical Systems, Milwaukee, WI). Contrast-enhanced CT images were obtained for all 10 patients, and unenhanced CT images were obtained for six patients (Table 1). MR imaging examination was performed with a 1 .5-T scanner (Signa [General Electric Medical Systems] or Magnetom [Siemens]) or a 1 .0-T scanner (Magnetom Impact; Siemens) that used superconducting magnet systems. Ti -weighted (400-600/11-15/2 [TR range/TE range/excitations]) and T2-weighted (1800-2000/80/2 [TR range/TE/excitations]) spin-echo MR images were obtained for all seven patients who underwent MR imaging examination. Presaturation pulses were used for the Tiand 12-weighted spin-echo images, and gradient moment nulling was used for the T2-weighted spin-echo images. Contrast-enhanced Ti -weighted spin-echo images were obtained for four patients after IV administration of 0.1

Osaka,

shot acquisition

one excitation). Unenhanced CT attenuation was classified into one of three groups on the basis of the predominant attenuation of the tumor:

spin echo.

AJR:166,

April

component, minor


and

one

and

round-cell

Correlation

included

The

component.

lipoma-like The

CT AND

1996

sclerosing

Between

Well-differentiated nents: lipoma-like components seen

a lipoma-like

pleomonphic

liposancoma

Imaging

MR IMAGING

subtypes

as

had no minor

Findings

liposancoma and sclenosing in seven of our

subtype

liposarcoma minor

as

a

included components.

components.

and Histologic can

OF ABDOMINAL

have

subtypes. The patients showed

Findings

two

compo-

lipoma-like low atten-

uation on CT images and high signal intensity on Ti- and T2-weighted spin-echo MR images; these findings nesembled those for subcutaneous fat (Figs. 1 and 2). The sclenosing components seen in five patients, on the other hand, showed CT attenuation or MR signal intensity that approxi-

LIPOSARCOMA

mated the characteristics of muscle (Fig. 2). On contrastenhanced CT images, septa within lipoma-like components were enhanced, and sclerosing components were enhanced homogeneously. Myxoid components seen in four patients showed predominant regions in which CT attenuation was less than that of muscle and MR signal intensity was similar to that of waterhypointense compared with muscle on Ti -weighted spin-echo images and hypenintense compared with fat on T2-weighted spin-echo images. T2-weighted spin-echo MR images also indicated septa of low signal intensity within these components. Before contrast enhancement, myxoid components showed CT attenuation and MR signal intensity similar to that of water. After contrast enhancement, gradual reticular enhancement was seen within the myxoid components (Fig.

Fig. 1 .-65-year-oId woman with lipoma-like, well-differentiated Ilposarcoma orIginating from mesosigmoid. A, Contrast-enhanced CT Image shows huge fatty tumor with septa and calcificatlons. Sigmoid colon (thin arrows) and inferior mesenteric and vein (thick arrow) are surrounded by tumor. B, Ti-weighted (600/12/2 [TRITE/excItations]) spin-echo MR image shows tumor to be predominantly isointense in relation to subcutaneous C, T2-weighted (1800/80/2) spin-echo MR Image also shows tumor to be predominantly Isointense in relation to subcutaneous fat.

Fig. 2-43-year-old A, Contrast-enhanced

83i

artery fat.

woman with pleomorphic liposarcoma having well-differentiated subtypes (lipoma like and sclerosing) as minor components. CT image shows huge mass displacing left kidney in left retroperitoneum. Lipoma-like component appears as area of fatty attenuation. Round region of pleomorphic component (thick arrows) and sclerosing components (thin arrows) infiltrate lipoma-like component and appear as areas of less fatty attenuation. Note that it is impossible to differentiate pleomorphic component from sclerosing components by attenuation on this CT image. B, Ti -weighted (600/i 5/2 [TRITE/excitations]) spin-echo MR image shows pleomorphic component (thick arrows) and sclerosing components (thin arrows) to be isointense in relation to muscle. Lipoma-like component appears isointense in relation to subcutaneous fat. C, T2-weighted (1800/80/2) spin-echo MR image shows that pleomorphic component has high signal intensity, like that of subcutaneous fat (thick arrows), whereas sclerosing components have low signal Intensity, like that of muscle (thin arrows). Lipoma-like component appears isointense in relation to subcutaneous fat.


AJR:166, April 1996

KIM ETAL.

832

Fig. 3.-63-year-old woman with myxoid llposarcoma In retroperitoneum. A, Unenhanced image shows tumor (arrows) to be hypoattenuated in relation

to muscle. Reticular pattern is seen within tumor. B, Contrast-enhanced CT scan obtained 1 mm after injection of contrast medium. Tumor shows gradual reticular enhancement (arrows). C, Contrast-enhanced CT scan obtained 3 mm after injection of contrast medium. Tumor shows gradual retlcular enhancement (arrows). 0, Ti-weighted (600115/2 [TRITE/excItations]) spin-echo MR Image shows tumor to be hypomntense In relatIon to muscle. E, T2-welghted (I 800/80/2) spin-echo MR image shows tumor to be predominantly hyperintense In relation to subcutaneous fat and also shows septa (arrows) with low signal intensIty. F, Contrast-enhanced Ti -weighted (600/1 5/2) spIn-echo MR image shows reticular enhancement in tumor.

3). A large area of one myxoid liposancoma enhanced markedly. Although myxoid components appeared to be cystic lesions before contrast enhancement, they appeared to be solid lesions after contrast enhancement. The pleomorphic component seen in one patient showed CT attenuation approximating that of muscle. Signal intensity was equal to that of muscle on Ti -weighted spin-echo MR images and equal to that of fat on T2-weighted spin-echo MR images. Thus, the pleomorphic component that resembled the sclenosing subtype on the basis of CT attenuation differed from it on the basis of MR signal intensity (Fig. 2). The patient with round-cell liposancoma had multiple tumors. CT attenuation of round-cell components approximated muscle attenuation in the retnopenitoneum, as did CT attenuation

of the

sclerosing

subtype.

However,

although

the

Reports have correlated imaging findings and histologic subtypes of liposarcoma in the extremities [5, 7]. Liposarcomas sometimes

include

multiple

histologic

subtypes

within

the same

lesion [5]. Such histologic subtypes are usually classified on the basis of the most aggressive cellular component. However, the CT and MR appearances of liposarcomas can vary according to the combination of these histologic subtypes [5, 7]. Variable CT attenuation or MR signal intensity throughout a lesion may result from different histologic tissue subtypes found in that lesion. Thus, histologic subtypes should be considered for parts of a lesion that show variable appearances on CT and MR images. Well-differentiated liposarcomas in the extremities have been described as tumors with CT attenuation and MR signal intensity equal to those of fat. These tumors also can have thickened, irregular septa and minor nodular components with

sclerosing components were relatively homogeneous, the round-cell subtype appeared heterogeneous, with irregular hypoattenuation on contrast-enhanced CT images (Fig. 4). MR images of the round-cell subtype were not available. The findings for the tumors that had one on two histologic subtype components appeared to be a combination of the characteristic findings for the individual subtypes.

Discussion

Liposarcoma may anise in any region of the body that contains fat [1]. Liposarcoma is one of the most common malignant tumors in the netropenitoneum but is rare in the mesentery and in the penitoneum. Although liposarcoma has been reported to occur without a sex predilection [i], the patients that we studied were all women.

Fig. 4.-49-year-old woman with round-cell Ilposarcoma in retroperitoneum. Contrast-enhanced CT image shows multiple heterogeneous nonfatty masses In retroperltoneum (white arrows). Invasion into left kidney also Is seen (black arrows).

AJR:166,

1996

CT AND

MR IMAGING

OF ABDOMINAL

on CT scans approximating that of skeletal muscle. Focal areas of well-differentiated liposarcomas on T2-weighted spin-echo images may have a signal that is hypenntense relative to that offat [5]. The lipoma-like component, which is one of the well-differentiated subtypes, usually contains fat. Fat within the tumor may lead to a diagnosis of liposarcoma, although abdominal tumors with fat are not always liposarcomas [8, 9]. It has been suggested that the greaten the fat component within a liposancoma, the lower the tumor should be graded histologically [7, 10]. The sclerosing component, which also is one of the well-differentiated subtypes, showed CT attenuation and MR signal intensity that approximated the characteristics of muscle. Less fatty liposarcomas composed of myxoid, pleomorphic, on round-cell subtypes have been reported [5]. The sclerosing subtype also could produce a nonfatty liposarcoma. In this study, myxoid liposarcomas showed CT attenuation less than that of muscle and a homogeneous MR signal intensity similar to that of waten-hypointense Compared with muscle on Ti-weighted spin-echo images and hyperintense compared with fat on T2-weighted spin-echo images-like previously reported Iiposarcomas in the extremities [5, 7]. On CT and MR images, although the myxoid liposarcomas of our patients appeared to be cystic lesions before contrast enhancement, they appeared to be solid lesions showing gradual reticular enhancement after contrast enhancement. These findings, which we believe result from the myxomatous interstitial content and fibrous tissue within this tumor subtype, may prove useful in differentiating such tumors from other benign abdominal Cystic tumors or malignant necrotic tumors (e.g., leiomyosarcoma). Round-cell and pleomorphic liposarcomas were heterogeneous, nonfatty tumors, as previously described [5]. Their characteristics were indistinguishable from those of other malignant soft-tissue masses (e.g., leiomyosarcoma and malignant fibrous histiocytoma) [ii]. We found that lipoma-like and myxoid liposancomas showed characteristic CT and MR appearances. Sclerosing, pleomorphic, and round-cell liposarcomas showed similar CT attenuaattenuation


April

tion.

LIPOSARCOMA

However,

the

MR

833

signal

intensity

of

the

sclerosing

component was different from that of the pleomorphic component on T2-weighted spin-echo images. These differences may allow differentiation of the sclerosing subtype, typical of lowgrade malignancy, from the pleomorphic subtype, typical of high-grade malignancy. However, further study is needed because our study group included few cases of these subtypes. In conclusion, we emphasize that a clear understanding of the imaging appearances of histologic subtypes of liposarcoma should be helpful for diagnosis and for predicting the prognosis for a patient with liposarcoma because histologic subtypes affect the prognosis.

REFERENCES 1 . Evans HL. Liposarcomas

and atypical lipomatous tumors: a study of 66 cases followed for a minimum of 10 years. Surg Pathol i988;1:41-54 2. Moyama TN. Primary mesenteric liposarcoma. Am J (3astroenterol 1988; 83:89-92 3. Entenline HT, Cuiberson JO, Rochlin DB, et al. Liposarcoma: a clinical and pathological study of 53 cases. Cancer i960;13:932-950 4. Enzinger FM, Weiss SW. Soft tissue tumors, 2nd ed. St. Louis: MosbyYear Book, 1988:346-382 5. Jelinek

JS,

Kransdort

Liposarcoma types.

MJ, Shmookler

of the extremities:

Radiology

Aboulafia

AJ,

Malawer

MM.

i993;i86:455-459

6. Reitan JB, Kaalhus 0, Brennhovd Prognosis 7. Sundaram

BM,

MR and CT findings in the histologic sub-

factors in liposarcoma. M, Baran G, Merenda

10, Sager EM, Stenwig AE, Talle K. Cancer i985;55:2482-2490 G, McDonald DJ. Myxoid

magnetic resonance imaging appearance relation. Skeletal Radiol i990;i9:359-362

liposarcoma:

with clinical and histologic

cor-

8. Dooms GS, Hnicak H, Sollitto A, Higgins C. Lipomatous tumors and tumors with fatty component: MR imaging potential and comparison of MR and CT results. Radiology 1985;i57:479-483 9. Friedman AC, Hartman OS, Sherman J, Lautin EM, Goldman M. Computed tomography of abdominalfatty masses. Radiology 1981139:415-429 10. Do Santos LA, Ginaldi S, Wallace S. Computed tomography in liposarcomas. Cancer 198147:46-54 11. Benquist TH, Ehman AL, King BF, Hodgman CG, llstrup DM. value of MR imaging in differentiating benign from malignant soft tissue masses: study of 95 lesions. AJR i990;155:125i-1255


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46. Keiji Matsumoto, Masahiko Takada, Hidetoshi Okabe, Michihito Ishizawa. 2000. Foci of signal intensities different from fat in well-differentiated liposarcoma and lipoma: correlation between MR and histological findings. Clinical Imaging 24, 38-43. [CrossRef] 47. Datla G.K. Varma. 1999. Optimal radiologic imaging of soft tissue sarcomas. Seminars in Surgical Oncology 17:10.1002/ (SICI)1098-2388(199907/08)17:11.0.CO;2-9, 2-10. [CrossRef]