AJR 2001; 176:1455-1457
© American Roentgen Ray Society
Multiple Mobile Spherules in Mature Cystic Teratoma of the Ovary
Satomi Kawamoto1,2,
Katsuhiko Sato3,
Hiroshi Matsumoto4,
Yoshichika Togo4,
Yoshihiko Ueda5,
Junji Tanaka1 and
Atsuko Heshiki1
1
Department of Radiology, Saitama Medical School, 38 Morohongo Moroyama Iruma,
Saitama, 350-0495 Japan.
2
Department of Radiology, Otsu Municipal Hospital, 2-9-9 Motomiya Otsu, Shiga,
520-0804 Japan.
3
Department of Radiology, Kasukabe Municipal Hospital, 7-2-1 Chuo Kasukabe,
Saitama, 344-0067 Japan.
4
Department of Obstetrics and Gynecology, Kasukabe Municipal Hospital, Saitama,
344-0067 Japan.
5
Department of Pathology, Dokkyo University, School of Medicine, 880
Kitakobayashi Mibu Shimotsuga, Tochigi, 321-0293 Japan.
Received September 20, 2000;
accepted after revision December 5, 2000.
Address correspondence to S. Kawamoto.
Introduction
Mature cystic teratoma is one of the most common human germ cell tumors and
is often found in the ovary in women of reproductive age. Ovarian cystic
teratomas are usually cystic fatty tumors that can be diagnosed without
difficulty using CT [1,
2] and MR imaging
[3].
We present a case of a 24-year-old woman with multiple spherical structures
floating in a large cystic mass in the lower abdomen and pelvis seen on
sonographic and MR images. A mature cystic teratoma of the ovary was the
presumed preoperative diagnosis. The patient underwent excision of the lesion,
and pathologic diagnosis was consistent with a mature cystic teratoma. The
striking aspect of multiple spherical structures in the cyst was caused by
multiple spherical desquamative keratin formations.
Case Report
A 24-year-old woman presented with a 1-year history of abdominal fullness
and lower abdominal pain during menstruation. Physical examination revealed a
large mass in the lower abdomen and pelvis. She was slightly anemic; her
hematocrit was 34.5%. The tumor markers were normal except for minimal
elevation of CA 19-9 (39.0 U/mL; normal, <35 U/mL) and immunosuppressive
acidic protein (659 µg/mL; normal, <500 µg/mL). Sonography showed a
large cystic mass in the lower abdomen and pelvis. Multiple mobile spherical
structures of increased echogenicity were floating in the cystic mass
(Fig. 1A).
MR imaging was performed for further characterization of the lesion. A
cystic mass measuring 22 x 24 x 12.5 cm occupied the lower abdomen
and pelvis, extending to the level of the upper pole of the kidneys. There
were numerous small spherical structures approximately 1 cm in diameter and
two larger ones (3-4 cm) floating in the nondependent portion of the cystic
mass. On sagittal T1-weighted images, the outer portion of the spherical
structures was slightly hyperintense to the surrounding fluid, but not as
hyperintense as subcutaneous fat. The center of the spherical structures was
relatively hypointense compared with the outer portion. There was a
fluid—debris level in the dependent portion of the cystic mass
(Fig. 1B). On sagittal and
coronal T2-weighted images, the outer portion of the spherical structures was
hypointense, and the center relatively hyperintense (Figs.
1C and
1D). The normal left ovary
could not be identified. The uterus and the right ovary were of normal
appearance, and no other abnormal findings were detected in the abdomen or
pelvis. Mature cystic teratoma arising from the left ovary was considered as a
preoperative diagnosis.
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Fig. 1B. —24-year-old woman with mature cystic teratoma. Sagittal
T1-weighted MR image shows large cystic mass occupying lower abdomen and
pelvis. Spheres approximately 1 cm in diameter and larger float in
nondependent portion of cystic mass. Outer portion of spherical structures is
slightly hyperintense to surrounding fluid, but not as hyperintense as
subcutaneous fat. Note fluid—debris level in dependent portion.
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Fig. 1C. —24-year-old woman with mature cystic teratoma. Sagittal
(C) and coronal (D) T2-weighted MR images show spheres floating
in large cystic mass. Outer portion of spherical structures are hypointense,
and center is relatively hyperintense.
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Fig. 1D. —24-year-old woman with mature cystic teratoma. Sagittal
(C) and coronal (D) T2-weighted MR images show spheres floating
in large cystic mass. Outer portion of spherical structures are hypointense,
and center is relatively hyperintense.
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Laparotomy revealed a large cystic tumor of the left ovary. The tumor
contained numerous small and two larger black spherical structures
(Fig. 1E). Hair was present in
some of these spherical structures. The internal surface of the cystic tumor
was smooth, and there was no solid component. The right ovary and the uterus
were normal.
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Fig. 1E. —24-year-old woman with mature cystic teratoma. Photograph of
gross specimen of cystic mass seen from internal surface with emptied contents
shows tumor containing numerous black spheres the size of blue-berries. Also
note large spheres. Internal surface of cystic tumor is smooth and lacks solid
component.
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The diagnosis at pathology was mature cystic teratoma of the ovary.
Contained within the cyst wall were cartilage, skin and its appendices,
muscle, ganglion, peripheral nerve, salivary gland, and fatty tissue. There
was no evidence of immature features, and no evidence of malignancy. A
striking finding was numerous dark black, small spherical structures of a
claylike material within the cyst. Two larger spherical structures also had
similar texture. Microscopic examination found desquamative keratin spherules
containing fibrin, hemosiderin, and hair. Azan stain failed to show a fat
component in these spherules.
The patient's postoperative course was uneventful, and she was discharged
12 days after surgery.
Discussion
Mature cystic teratoma is one of the most common human germ cell tumors,
and it is often found in the ovary of women of reproductive age. Generally,
the diagnosis is made using CT
[1,
2] and MR imaging
[3] without difficulty. The
presence of fatty and calcific (or osseous) elements is usually necessary for
a correct diagnosis [2]. Buy et
al. [4] reported that fat was
present in 93%, tooth or calcification in 56%, and a fat—fluid level in
12% of 43 cases of cystic teratomas of the ovary (41 benign and two with
malignant transformation) on CT scans. Typical imaging features of cystic
teratomas include layering or floating debris, or both, within a tumor, and
nodular or palm tree—like mural protrusions, known as Rokitansky
protuberances or dermoid plugs, containing hair and other atypical tissues
[2,
3]. Bone or tooth tends to
locate within this area [1,
2]. Curvilinear calcification
of the cyst wall may also be observed
[1].
Unusual associated findings of mature cystic teratoma may result in
occasional diagnostic difficulty. To our knowledge, only a small number of
cases of cystic teratoma with multiple mobile spherules or globules have been
reported in the literature. These lesions were found in the ovary
[5,
6], retroperitoneum
[7], and mediastinum
[8]. In the case of cystic
teratoma of the ovary, the nodules consisted of sebaceous debris with skin
squames and hair [6]. In mature
cystic teratoma of the mediastinum, mobile globules consisted of pastelike
material, fat, and hair [8]. In
retroperitoneal mature cystic teratoma, fat deposition was seen around hair
tissue [7]; these spherical
structures have been called intracystic fat balls
[5,
7]. In our patient, however,
fat was not revealed in the spherules with azan stain, but it was possible
that the fat component had dissolved during the fixation process. In the
reported cases and our patient, the center of the spherical structures showed
relatively lower signal intensity on T1-weighted MR images, corresponding to
hair or a softer component [5,
6]. It has been speculated that
each spherule was formed by the aggregation of sebaceous matter around a nidus
(a tiny focus of debris, disquamative material, or fine hair shaft), and may
be formed into a discrete mass because of the difference in physical and
thermal properties of the material being deposited
[7]. The specific gravity of
spherules or globules is lower than that of the surrounding fluid, so that
they float and are mobile in the cyst. Other than mature cystic teratoma,
similar multiple spherules in the cystic mass have been reported in a patient
with an epidermoid cyst in the floor of the mouth
[9]. In this case, the
spherules consisted of multiple spherical keratin formations. To the best of
our knowledge, the appearance of multiple spherules floating within a pelvic
cystic tumor has not been found in other tumors, and we think this appearance
is pathognomonic for a cystic teratoma.
In summary, we present a case of mature cystic teratoma of the ovary
containing numerous spherules floating in the cyst. Sonography and MR imaging
revealed numerous spherical structures floating in the cystic mass, which is
thought to be pathognomonic for a cystic teratoma. Microscopically, these
spherical structures were composed of desquamative keratin containing fibrin,
hemosiderin, and hair.
Acknowledgments
We thank Hisataka Kobayashi for valuable discussion and editorial
assistance.
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Introduction
Case Report
