DOI:10.2214/AJR.04.1799
AJR 2006; 186:320-323
© American Roentgen Ray Society
Atypical Polypoid Adenomyoma of the Uterus: Appearance on 18F-FDG PET/MRI Fused Images
Tetsuo Maeda1,
Ukihide Tateishi1,
Yuko Sasajima2,
Tadashi Hasegawa2,
Hiromitsu Daisaki3,
Yasuaki Arai1 and
Kazuro Sugimura4
1 Division of Diagnostic Radiology, National Cancer Center Hospital, 5-1-1,
Tsukiji, Chuo-Ku, Tokyo, Japan 104-0045.
2 Division of Pathology, National Cancer Center Research Institute, Tokyo,
Japan.
3 Division of Diagnostic Radiology, Research Center for Cancer Prevention and
Screening, National Cancer Center Hospital, Tokyo, Japan.
4 Department of Radiology, Kobe University Graduate School of Medicine, Chuo-ku,
Kobe 650-0017 Hyogo, Japan.
Received November 19, 2004;
accepted after revision January 10, 2005.
Address correspondence to U. Tateishi.
Keywords: adenomyoma • MRI • PET • uterus • videofluoroscopy
Introduction
Atypical polypoid adenomyoma (APA) is a rare polypoid tumor of the uterus
composed of atypical endometrial glands surrounded by smooth muscle
[1]. It generally occurs in
women of reproductive age who have abnormal genital bleeding. Although it is
considered to be benign, adenocarcinoma is occasionally found in resected
specimens [2].
MRI findings have been reported in a few cases of APA
[3]. However, to the best of
our knowledge, the 18F-FDG PET appearance of APA has not been
reported. Here we describe a case of APA identified on 18F-FDG PET
combined with MRI in which malignancy could not be ruled out.
Case Report
A 44-year-old nulliparous woman underwent a medical checkup for cancer
screening with FDG PET scanning. The patient was tested for a normal glucose
level (91 mg/dL) before PET scan. Emission scans from the base of the skull to
the midthigh were obtained starting 60 min after IV administration of 223.2
MBq of 18F-FDG. 18F-FDG PET images revealed a single
focus of abnormal 18F-FDG uptake in the uterus. The patient was
referred to our hospital for further examination and treatment. She was
asymptomatic and the physical examination was unremarkable. The serum
carcinoem-bryonic antigen, carbohydrate antigen 19–9, and carbohydrate
antigen 125 values were all within the normal range. MRI of the pelvis was
performed. T1-weighted MR images showed a polypoid mass in the endometrial
cavity that was isointense relative to myometrium.
On T2-weighted MR images, the mass was slightly hyperintense and contained
markedly hyperintense foci (Fig.
1A). Contrast-enhanced study showed irregular enhancement of the
tumor (Fig. 1B). PET and PET/MR
fused images localized the abnormality to the endometrial cavity (Figs.
1C and
1D). The standardized uptake
value (SUV) of the tumor was 5.8. The round shape of the polypoid mass and the
pattern of irregular enhancement resembled the findings in submucosal
leiomyoma of the uterus. However, the slight hyperintensity of the mass on
T2-weighted MR images and abnormal 18F-FDG uptake in the uterus
were inconsistent with an ordinary uterine leiomyoma.
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Fig. 1A —44-year-old woman with atypical polypoid adenomyoma of uterus.
Sagittal T2-weighted image (TR/TE, 4,000/90) showing polypoid mass with slight
hyperintensity and containing markedly hyperintense foci
(arrows).
|
|
Because we could not rule out a malignant tumor, a therapeutic hysterectomy
was performed. A 3.2 x 3.0 cm polypoid mass with yellowish white cut
surface arising from the anterior-to-lateral aspect of the lower uterine
segment was identified in the surgical specimens
(Fig. 1E). Histologically, it
was composed of hyperplastic endometrial glands admixed with a stromal
component consisting of interlacing bundles of smooth muscle cells
(Fig. 1F). No architectural
atypia of the glands was detected. Immunohistochemical staining of MIB-1
(Ki–67) revealed increased proliferative activity of the epithelial
cells in the endometrial glands (Fig.
1G), and a diagnosis of atypical polypoid adenomyoma of the uterus
was made. Recovery was uneventful, and the patient was discharged 11 days
after surgery. No local or systemic recurrences have been detected during the
first 2 months after surgery.
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Fig. 1F —44-year-old woman with atypical polypoid adenomyoma of uterus.
Photomicrograph shows hyperplastic endometrial glands (arrows)
admixed with stromal component of interlacing bundles of smooth muscle cells
(arrowheads).
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Fig. 1G —44-year-old woman with atypical polypoid adenomyoma of uterus.
Photomicrograph of MIB-1 immunohistochemical staining shows positive
epithelial cells of endometrial glands (arrows), which is suggestive
of strong proliferative activity.
|
|
Discussion
APA is considered to be a benign form of mixed epithelial and mesenchymal
uterine tumors, and the tumors often involve the lower uterine segments,
endocervix, or upper corpus
[4]. The histologic appearance
of APA is that of admixture of endometrial glands having varying degrees of
structural atypia and a stroma predominantly consisting of smooth muscle
cells. Several cases have been reported of APA accompanied by the foci of
endometrial carcinoma in the previous studies
[1,
2]. Although the association
between APA and endometrial carcinoma is unclear, recognition and correct
diagnosis are important.
The PET image in our patient showed focal intense accumulation of
18F-FDG consistent with the polypoid uterine mass and suggested a
malignant tumor. Although 18F-FDG uptake by tissue is a sensitive
indicator of a malignant tumor, identifiable focal 18F-FDG uptake
is sometimes seen in benign uterine tumors
[5]. Leiomyoma of the uterus is
the most common uterine benign neoplasm and often shows moderately intense
18F-FDG accumulation
[6]. Holder et al.
[7] reported that several
benign tumors, including a leiomyoma of the uterus, took up enough
18F-FDG to produce false-positive results for melanoma. The
mechanism of 18F-FDG uptake in our patient's tumor is uncertain.
However, pathologic examination of the resected specimens in our case revealed
strong proliferative activity in the epithelium of the endometrial glands in
the tumor. A positive correlation between degree of 18F-FDG uptake
and the proportion of MIB-1-positive cells has been described in previous
studies [8]. Active
proliferation of tumor cells may be associated with increased accumulation of
18F-FDG, even in benign tumors.
MRI findings in our case were characteristic. Yamashita et al.
[3] reported the MR appearance
of three cases of APA. In their study, a polypoid mass was visualized as a
mixture of hypointensity and hyperintensity on T2-weighted MR images, and
contrast-enhanced study showed irregular enhancement of the tumor. These MRI
findings are consistent with those in our case.
In summary, APA of the uterus is visualized as a polypoid mass with
abnormal uptake of 18F-FDG in the endometrial cavity on PET/MR
fused images. APA should be included in the differential diagnosis whenever
increased 18F-FDG uptake by a polypoid uterine tumor is
observed.
Acknowledgments
We wish to express our sincere thanks to Tatsushi Kobayashi, Ryuichiro
Tunematsu, Mitsuo Satake, and Noriyuki Moriyama for assistance with the data
collection.
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Introduction
Case Report
