AJR 2002; 179:1068-1070
© American Roentgen Ray Society
Cystic Adenomatoid Tumor of the Uterus
Jin Young Kim1,
Kyung-Jae Jung1,
Nak Kwan Sung1,
Duck Soo Chung1,
Ok Dong Kim1 and
Soyoon Park2
1 Department of Radiology, School of Medicine, Catholic University of Daegu,
3056-6, Daemyung 4-Dong, Nam-gu, Daegu 705-718, Korea.
2 Department of Diagnostic Pathology, School of Medicine, Catholic University of
Daegu, Daegu 705-718, Korea.
Received January 7, 2002;
accepted after revision February 28, 2002.
Address correspondence to K.-J. Jung.
Introduction
A cystic variant of an adenomatoid tumor is a rare benign tumor that may
arise in the uterus
[1,2,3,4,5].
It is thought to be of mesothelial origin and is usually very small
[1,2,3,4,5].
To our knowledge, no reports exist about the MR imaging findings of cystic
variants of the tumor. We report the sonographic and MR imaging features of a
histologically confirmed large cystic adenomatoid tumor of the uterus and
relate those features to pathologic findings.
Case Report
A 40-year-old woman presented with a history of menorrhagia. Physical
examination revealed uterine enlargement. She was slightly anemic; her
hemoglobin was 11.4 g/dL. Sonography performed 2 years previously showed
negative findings in the uterus. Current sonography showed a large
multilocular cystic mass in the left side of the uterus
(Fig. 1A). The mass was located
subserosally. Each loculus was free from echoes and was separated by a thin
smooth septum. The wall of the lesion was imperceptible. No dilated veins were
detected around the lesion on Doppler sonography. Our first impression was of
a large leiomyoma with cystic degeneration.
MR imaging was performed for further characterization of the lesion. A
cystic mass measuring 5.2 x 3.2 x 4.3 cm was seen in the uterine
myometrium (Figs. 1B and
1C). The lesion showed the same
signal intensity as that of water: homogeneous low signal intensity on
T1-weighted images (Fig. 1B)
and high signal intensity on T2-weighted images
(Fig. 1C). A thin hypointense
rim was seen around the lesion on T2-weighted images. On gadopentetate
dimeglumine—enhanced T1-weighted images
(Fig. 1D), the septa were
well-enhanced similar to adjacent normal myometrium. No enhancing solid
portion was seen.
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Fig. 1C. —40-year-old woman with cystic adenomatoid tumor. T2-weighted
axial MR image shows thin smooth septum traversing mass. Thin hypointense rim
surrounds mass (arrows), which suggests compressed normal
myometrium.
|
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Laparotomy revealed a large subserosal cystic lesion on the left anterior
uterine surface. Clear fluid gushed from the mass on incision. At gross
inspection, the mass showed a multilocular appearance
(Fig. 1E). Surrounding
compressed myometrium correlated with the hypointense rim seen on T2-weighted
images. Microscopic examination revealed that the spaces were lined with
flattened cuboidal cells (Fig.
1F). Immunohistochemical staining showed the presence of
cytokeratin in the cytoplasm of the lining cells.
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Fig. 1E. —40-year-old woman with cystic adenomatoid tumor. Gross
specimen shows uterine tumor consisting of multiple cystic cavities containing
pale yellow clear fluid. No solid nodules are seen.
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Fig. 1F. —40-year-old woman with cystic adenomatoid tumor.
Histopathologic specimen shows tumor to be primarily composed of cystic spaces
lined by single layer of flattened cuboidal cells with oval nuclei. (H and E,
x200)
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Discussion
Adenomatoid tumors are relatively rare benign neoplasms that usually arise
in the genital tract
[1,2,3,4].
The tumor is most frequently observed in the male genitalia such as the
epididymis [3]. It also appears
in the female genitalia, most commonly in the fallopian tubes. The next most
common locations are the uterus and ovaries
[2]. Rarely, these tumors may
originate in extragenital sites such as the adrenal gland, omentum, and
mesentery [2,
6]. The histogenesis of
adenomatoid tumors is controversial; mesonephric, müllerian, endothelial,
and mesothelial origins have been suggested. Previous studies based on
transmission electron microscopy, scanning electron microscopy, and
immunohistology support a mesothelial origin
[1,2,3,4,5].
The incidence of adenomatoid tumors in the uterus has been reported in one
series to be 1.2% [7]. However,
the true incidence is probably greater because these tumors frequently go
unsampled as a result of their small size and gross appearance, which is
similar to that of leiomyomas
[3,
4]. Most large adenomatoid
tumors are located subserosally in the posterior wall of the fundus or near
the cornua [4,
5]. Almost all adenomatoid
tumors of the uterus are solitary, asymptomatic tumors that are incidentally
discovered in hysterectomy specimens
[6].
Several histologic types of adenomatoid tumors are found. Quigley and Hart
[6] described four types:
adenoid, angiomatoid, solid, and cystic. Combinations of two or more patterns
occurred in each tumor. The most frequent types are the adenoid and the
angiomatoid.
The cystic type is the least common type and is very rare
[1,2,3,4,5]
but has been reported in the pathology literature in several case reports
[1,
3,4,5].
Locations were intramural [1]
and subserosal
[3,4,5].
The tumor of our patient was located subserosally. Two of four reported cases
showed multilocular cystic appearances with small or large solid areas
[1,
5]. These cases probably were a
combination of cystic and other types. The other two cases showed a purely
cystic appearance with no solid portion
[3,
4]. Our case was purely cystic;
no solid portion was seen.
The cross-sectional imaging findings of uterine adenomatoid tumor have been
reported in only a few cases
[2]. CT and MR imaging findings
of these tumors simulated the findings of uterine leiomyoma, and pre-operative
diagnosis was difficult. Mitsumori et al.
[2] described the MR imaging
findings of two cases of the angiomatoid type. The tumors showed low signal
intensity on T2-weighted images and gadopentetate dimeglumine—enhanced
T1-weighted images and isointensity on T1-weighted images. A flow void was
seen in the periphery of the tumor. Mitsumori et al. presumed that cystic
types probably have a multilocular appearance on MR images. They concluded
that the radiologic findings of adenomatoid tumor may range from a solid tumor
to a cystic tumor depending on the content of the cystic spaces, smooth
muscle, and fibrous tissue.
To our knowledge, no reports exist of the MR imaging findings of cystic
adenomatoid tumor of the uterus. Our case showed good correlation between the
MR imaging and pathologic findings. MR imaging revealed the multilocular
appearance of the mass with no enhancing solid portion. Both sonography and MR
imaging showed an imperceptible wall of the lesion.
Differential diagnoses of large cystic uterine lesions include cystic
degeneration of uterine leiomyoma, cystic adenomyosis (adenomyotic cysts),
congenital uterine cysts such as mesonephric and paramesonephric cysts,
cervical nabothian cysts, intramyometrial hydrosalpinx, and echinococcal cysts
[8]. Relatively large
leiomyomas have a potential for malignancy, but many of them respond to
hormone therapy. In contrast, recurrence or metastasis has never been
reported, and the effectiveness of hormone therapy is unclear in adenomatoid
tumors [2,
3]. In most cases,
differentiating between an adenomatoid tumor and a leiomyoma is impossible,
regardless of whether the lesion is cystic. Cystic adenomyosis has MR imaging
findings similar to those of hematomas and a hypointense rim on T2-weighted
images [8]. Various kinds of
congenital cysts cannot be differentiated from cystic adenomatoid tumor. In
our patient, congenital cyst could be excluded because of the absence of the
lesion on the previous sonograms.
In summary, we report a case of cystic adenomatoid tumor of the uterus,
which is an exceedingly rare benign tumor. Our patient presented with
significant symptoms and required hysterectomy. Although to our knowledge the
imaging findings of this tumor have not been reported previously in the
radiology literature, it is not surprising that this tumor shows a
multilocular cystic appearance with no solid portion. Sonographic and MR
imaging findings of this tumor correlated well with pathologic results.
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Introduction
Case Report
