AJR 2003; 181:1369-1374
© American Roentgen Ray Society
CT and MRI of Uterine Sarcomas and Their Mimickers
Sung Eun Rha1,
Jae Young Byun1,
Seung Eun Jung1,
Soo Lim Lee1,
Song Mee Cho1,
Seong Su Hwang1,
Hae Giu Lee1,
Sung-Eun Namkoong2 and
Jae Mun Lee1
1 Department of Radiology, College of Medicine, The Catholic University of
Korea, 505, Banpo-Dong, Seocho-Ku, Seoul 137-040, South Korea.
2 Department of Obstetrics and Gynecology, Kangnam St. Mary's Hospital, Seoul
137-040, South Korea.
Received February 3, 2003;
accepted after revision March 18, 2003.
Address correspondence to J. Y. Byun.
Introduction
Uterine sarcomas are rare tumors of mesodermal origin, constituting only
2–6% of uterine malignant tumors
[1]. The three most common
histologic variants of uterine sarcomas are malignant mixed müllerian
tumors, leiomyosarcomas, and endometrial stromal sarcomas. Uterine sarcomas
are, in general, the most malignant group of uterine tumors; they differ from
endometrial cancers with regard to diagnosis, clinical behavior, pattern of
spread, and management [1]. The
distinction among the various subgroups of uterine sarcoma and between uterine
sarcomas and other uterine tumors cannot be made on clinical grounds.
Therefore, imaging studies, particularly CT and MRI, are important for
evaluating the pelvic mass at presentation and for aid in staging the tumor.
This pictorial essay discusses the clinical and imaging features of each of
the subtypes of uterine sarcoma and their mimickers.
Malignant Mixed Müllerian Tumors
Malignant mixed müllerian tumors are the most common of the uterine
sarcomas and constitute about 2% of all corpus malignant tumors. Malignant
mixed müllerian tumors are quite malignant and contain both carcinomatous
and sarcomatous components. The epithelial component is usually an
adenocarcinoma, and stromal sarcoma is the most common type of sarcoma
[1]. Interestingly, 4–38%
of patients with malignant mixed müllerian tumors have received pelvic
irradiation for unrelated pelvic malignancies several years before the
symptoms [2].
A malignant mixed müllerian tumor usually grows as a large solid mass
replacing the endometrial cavity; necrosis and hemorrhage are prominent
features (Figs. 1,
2A,
2B,
3). The myometrium is invaded
to various degrees in almost all cases. Malignant mixed müllerian tumor
is usually in the fundus but can involve the cervix and sometimes presents as
a protruding mass from the cervical os. Although malignant mixed
müllerian tumors may metastasize hematogenously, local and lymphatic
spread and intraperitoneal seeding are more common
[3] (Figs.
2A,
2B and
3).
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Fig. 1. —67-year-old woman with malignant mixed müllerian tumor.
Sagittal T2-weighted (TR/TE, 2,000/80) spin-echo image shows markedly
distended endometrial cavity (E) with peripheral polypoid masses. Patient had
history of pelvic irradiation for cervix carcinoma 12 years previously. These
characteristic imaging features are probably caused by stenosis of cervical
canal resulting from previous pelvic irradiation.
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Fig. 2A. —73-year-old woman with malignant mixed müllerian tumor.
Sagittal T2-weighted spin-echo image (TR/TE, 2,000/80) shows polypoid
endometrial mass (M) distending uterine cavity. Bulky peritoneal mass
(arrows) is also present in cul-de-sac, suggesting peritoneal
metastasis.
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Fig. 2B. —73-year-old woman with malignant mixed müllerian tumor.
Sagittal gadolinium-enhanced fat-suppressed T1-weighted spin-echo image
(583/11) shows irregular central nonenhancing necrotic portion of peritoneal
mass (arrows). Almost all of these tumors occur after menopause, at
median age of 62 years. Most frequent presenting symptom is bleeding. M =
endometrial mass.
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Fig. 3. —62-year-old woman with malignant mixed müllerian tumor.
Contrast-enhanced CT scan shows markedly enlarged uterus totally replaced by
mass and focal disruption of uterine margin (arrowheads). Note
inhomogeneous contrast enhancement and calcification. Lobulated peritoneal
mass (arrows) is noted anterior to main mass. Ascites (f) is also
seen. Intraperitoneal metastases are more common than hematogenous metastases
in malignant mixed müllerian tumors. Peritoneum is usually involved in
more than half of cases extending beyond uterus. Extent of tumor at time of
diagnosis is most important prognostic factor.
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Leiomyosarcomas
Leiomyosarcomas account for one third of uterine sarcomas. Leiomyosarcomas
may arise either de novo from uterine musculature or the connective tissue of
uterine blood vessels or in a preexisting leiomyoma. The incidence of
sarcomatous change in benign uterine leiomyomas is reported to be
0.1–0.8% [4].
Leiomyosarcoma usually presents as a massive uterine enlargement with
irregular central zones of low attenuation, suggesting extensive necrosis and
hemorrhage (Fig. 4). Foci of
calcification may be present. The pattern of tumor spread is to the
myometrium, pelvic blood vessels and lymphatics, contiguous pelvic structures,
abdomen, and then distantly, most often to the lungs. Although it has been
suggested that an irregular margin of a uterine leiomyoma on MRI is suggestive
of sarcomatous transformation, the specificity of this finding has not been
established [5].
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Fig. 4. —73-year-old woman with uterine leiomyosarcoma. Sagittal
gadolinium-enhanced T1-weighted spin-echo image (TR/TE, 200/20) shows massive
uterine enlargement (arrows) with irregular central zones of low
signal intensity, suggesting extensive tumor necrosis (N). Uterine
leiomyosarcoma should be suspected if rapid uterine enlargement occurs,
especially in post-menopausal women. Because most leiomyosarcomas are located
in myometrium, endometrial biopsy is not as useful as in other sarcomas, but
it may establish diagnosis in as many as one third of patients in whom lesion
is submucosal.
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Endometrial Stromal Sarcomas
Endometrial stromal sarcomas constitute 0.2% of all uterine malignancies
and 15–23% of primary uterine sarcomas. There is no relationship to
parity, associated disease, or prior pelvic radiotherapy. Pathologically,
endometrial stromal sarcoma is further subdivided into low-grade stromal
sarcoma and high-grade stromal sarcoma, each of which shows different clinical
presentations and outcomes.
Low-Grade Endometrial Stromal Sarcomas
Low-grade endometrial stromal sarcomas tend to occur in a younger age group
than do high-grade endometrial stromal sarcomas. Low-grade endometrial stromal
sarcomas tend to invade extensively into the myometrium and surrounding
structures, even with scant cytologic atypia. The imaging findings of
low-grade endometrial stromal sarcomas are variable, from a polypoid
endometrial mass to a myometrial mass mimicking intramural myoma with cystic
degeneration [6] (Figs.
5 and
6A,
6B).
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Fig. 5. —40-year-old woman with low-grade endometrial stromal sarcoma.
Contrast-enhanced CT scan shows relatively well-defined low-density myometrial
mass (arrows) that cannot be differentiated from intramural myoma on
this scan. Usual preoperative diagnosis of low-grade endometrial stromal
sarcoma is leiomyoma with unusual degree of bleeding. On CT scans, some cases
of low-grade endometrial stromal sarcoma cannot be clearly differentiated from
myoma. However, on MRI, endometrial stromal sarcoma usually has infiltrative
margin and shows high-signal intensity on T2-weighted images. B = bladder.
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Fig. 6A. —42-year-old woman with low-grade endometrial stromal sarcoma.
Axial fat-saturated T2-weighted spin-echo image (TR/TE, 2,000/80) shows large
relatively well-marginated hyperintense mass (solid arrows) in left
lateral wall of uterus. Endometrial cavity is not distended (open
arrows).
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Fig. 6B. —42-year-old woman with low-grade endometrial stromal sarcoma.
Axial gadolinium-enhanced T1-weighted image (417/11) shows multiple internal
septalike enhanced areas in mass (arrows), which was located
predominantly in myometrium on pathologic examination. Presence of bands of
low signal intensity in areas of myometrial involvement of low-grade
endometrial stromal sarcoma on T2-weighted images may be important imaging
finding for low-grade endometrial stromal sarcoma. Pathologically, this
imaging finding is considered to be preserved myometrial bundles separated by
tumor cells.
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High-Grade Endometrial Stromal Sarcomas
High-grade endometrial stromal sarcomas have a much more aggressive course
and a poorer prognosis than low-grade endometrial stromal sarcomas and tend to
occur in an older age group. High-grade endometrial stromal sarcomas
infiltrate the myometrium in a more destructive manner and are associated with
areas of hemorrhage and necrosis
[7]. MRI reveals a voluminous
polypoid mass in an expanded endometrial cavity, characterized by
heterogeneous signal intensity on both T1- and T2-weighted images (Figs.
7A,
7B,
7C and
8A,
8B). Continuous extension of
the lesion into the adjacent structures is frequently found on imaging because
of marked vascular and lymphatic involvement of the tumor.
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Fig. 7A. —58-year-old woman with high-grade endometrial stromal
sarcoma. B = bladder, C = ovarian cyst. Sagittal T1-weighted gradient-echo
FLASH image (TR/TE, 162.3/4.8; flip angle, 80°) shows enlarged uterus with
large homogeneous low-signal-intensity mass located mainly in endometrial
cavity.
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Fig. 7B. —58-year-old woman with high-grade endometrial stromal
sarcoma. B = bladder, C = ovarian cyst. Sagittal T2-weighted turbo spin-echo
image (3,900/99) shows inhomogeneous increased signal intensity of mass
(arrowheads). Note focal invasion of deep myometrium
(arrow).
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Fig. 7C. —58-year-old woman with high-grade endometrial stromal
sarcoma. B = bladder, C = ovarian cyst. Gadolinium-enhanced T1-weighted image
(162.3/4.8) shows inhomogeneous contrast enhancement of mass. Gross specimen
(not shown) showed lobulated mass resembling fish flesh with hemorrhage and
necrosis.
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Fig. 8A. —High-grade endometrial stromal sarcoma in 20-year-old woman
who had profuse vaginal bleeding. (Reprinted with permission from
[9]) Axial T2 -weighted turbo
spin-echo image (TR/TE, 3,900/99) shows bulky lobulated intracavitary mass
(arrows). Tumor invasion of entire thickness of myometrium at
right-sided fundus (arrowhead) is well visualized.
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Fig. 8B. —High-grade endometrial stromal sarcoma in 20-year-old woman
who had profuse vaginal bleeding. (Reprinted with permission from
[9]) Axial contrast-enhanced
T1-weighted image (450/13) shows inhomogeneous contrast enhancement of uterine
mass (straight arrows) that extends through entire thickness of
myometrium (arrowhead). Endometrial cavity is mildly widened
(curved arrow). Diagnosis can be confirmed by endometrial biopsy.
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Mimickers of Uterine Sarcomas
Endometrial Carcinoma
Occasionally, advanced endometrial carcinoma cannot be differentiated from
endometrial stromal sarcoma or malignant mixed müllerian tumors by
imaging findings (Fig. 9).
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Fig. 9. —65-year-old woman with advanced endometrial carcinoma.
Sagittal T2-weighted turbo spin-echo image (TR/TE, 3,900/99) shows enlarged
uterus and diffuse tumor involving entire endometrial surface. Hydrometra (E)
is also present. Large amount of ascites (A) and peritoneal metastases
(arrows) are also seen. Advanced endometrial carcinoma cannot be
clearly differentiated from malignant mixed müllerian tumor on images.
However, in practice, most patients with endometrial carcinomas have tumors
that are confined to endometrium or that only superficially invade myometrium,
and most malignant mixed müllerian tumors or endometrial stromal sarcomas
tend to be massive with deep myometrial invasion on initial presentation.
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Lymphoma
Initial uterine involvement occurs in 1% of patients with lymphoma.
However, uterine involvement is more common as part of a generalized process,
as shown in 40–50% of these patients at autopsy. Imaging findings of
lymphoma involving the uterus are nonspecific
[8] (Fig.
10A,
10B).
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Fig. 10B. —48-year-old woman with uterine lymphoma. Contrast-enhanced CT
scan obtained at level above A shows multiple small, nodular
low-density lesions in both kidneys, suggesting multinodular form of renal
lymphoma. Although imaging findings of lymphoma involving uterus are
nonspecific, diffuse uterine enlargement, somewhat lobular contour, and
relatively homogeneous attenuation with multiple lymphadenopathy, can suggest
lymphoma involvement of uterus.
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IV Leiomyomatosis
IV leiomyomatosis can mimic endometrial stromal sarcoma because both
conditions have the tendency to extend as a contiguous tumor into the adjacent
vascular structures (Fig. 11A,
11B).
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Fig. 11A. —37-year-old woman with IV leiomyomatosis. Axial T2-weighted
image (TR/TE, 2000/80) shows lobulated high-signal-intensity mass in right
side of uterine body and another mass with same features in right adnexa.
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Fig. 11B. —37-year-old woman with IV leiomyomatosis. Axial T2-weighted
image (2,000/80) caudal to A shows that parametrial mass extends out
from uterine mass. Pathology confirmed diagnosis of IV leiomyomatosis. IV
leiomyomatosis is characterized by growth of histologically benign smooth
muscle initially into venous channels within broad ligament and then into
uterine and iliac veins. This IV growth takes form of visible, wormlike
projections extending out from a myomatous uterus into parametria toward
pelvic sidewalls. IV extension of endometrial stromal sarcoma must be
considered in differential diagnosis.
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Adenomyosis
Adenomyosis is a diffuse lesion involving the myometrium and is similar to
endometrial stromal sarcoma. However, adenomyosis exhibits ill-defined low
signal intensity with multifocal punctate high-signal-intensity spots on
T2-weighted images (Fig.
12).
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Fig. 12. —35-year-old woman with focal adenomyosis. Sagittal
T2-weighted turbo spin-echo image (TR/TE, 3,900/99) shows ill-defined
circumscribed area of low signal intensity in posterior wall of uterine body.
Multiple punctate foci of high signal intensity (arrowheads) that are
thought to represent hemorrhagic endometrial nests are scattered throughout
mass. These foci were also seen on T1-weighted images (not shown). In contrast
to adenomyosis, endometrial stromal sarcoma exhibits high signal intensity on
T2-weighted images.
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Myoma with Secondary Degeneration
Although nondegenerated myomas have a typical appearance at MRI,
degenerated myoma may mimic the imaging findings of uterine sarcoma (Fig.
13A,
13B).
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Fig. 13A. —42-year-old woman who has intramural leiomyoma with myxoid
and cellular degeneration. Sagittal T2-weighted turbo spin-echo image (TR/TE,
3,900/99) shows well-defined intramural mass (arrows) with high
signal intensity peripherally and irregular isointensity of signal in
myometrium centrally.
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Fig. 13B. —42-year-old woman who has intramural leiomyoma with myxoid
and cellular degeneration. Gadolinium-enhanced T1-weighted image shows poor
enhancement of periphery of mass and homogeneous enhancement of central
portion of mass (arrows). Pathologically, mass was identified as
intramural leiomyoma, its central portion showed cellular degeneration, and
its periphery showed myxoid degeneration. Degenerated myoma may mimic imaging
findings of uterine sarcomas.
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Conclusion
The imaging findings of uterine sarcomas are large uterine masses with
extensive hemorrhage and necrosis. However, the findings may be nonspecific,
and the diagnosis is based on pathologic findings. Knowledge of the imaging
spectrum and the clinical features of uterine sarcomas is important for
radiologists because imaging plays a crucial role in staging and
management.
Acknowledgments
We thank Bonnie Hami, Department of Radiology, University Hospitals of
Cleveland, Cleveland, OH, for her editorial assistance in the preparation of
this manuscript.
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Top
Introduction
Malignant Mixed Mullerian Tumors
