Echogenic Uterine Fluid Collection as an Unusual
Presentation of Endometrial Squamous Metaplasia
Pia V. Hurst, MD,1Melissa J. Nicosia, MD,1Ilina Datkhaeva, BA,1
Khushbakhat R. Mittal, MD,2and Ming C. Tsai, MD1
Background: The optimal management of intrauterine fluid accumulation in postmenopausal women with cer-
vical stenosis is currently debatable. Diagnostic challenge still remains, because of the low accuracy of sono-
graphic histologic prediction.Case: In the case described, an asymptomatic postmenopausalwoman was found to
have an echogenic endometrial fluid collection on pelvic ultrasound, suspicious for uterine malignancy. Results:
After a failed attempt at endometrial sampling secondary to cervical stenosis, the patient underwent a total
abdominal hysterectomy and bilateral salpingo-oophorectomy. The fluid-filled endometrial cavity was found to
have extensive benign squamous differentiation. Conclusions: Extensive endometrial squamous metaplasia
should be considered as a rare differential diagnosis when postmenopausal women are found to have echogenic
intrauterine fluid collections on ultrasound. (J GYNECOL SURG 29:148)
has long been considered a possible indication of serious
endometrial or cervical disease, including hyperplasia or can-
cer. No consensus exists regarding the optimal management of
asymptomatic postmenopausal women with intrauterine fluid
collection.1There is controversy as to whether the presence of
malignancy, or if it is solely a consequence of fluid accumula-
tion secondary to cervical stenosis. The sonographic aspect of
intrauterine fluid appears to be a predictor for malignant dis-
ease. In a study by Takacs et al. of postmenopausal women
with endometrial fluid collection, echogenic fluid in the endo-
metrial cavity was significantly more likely to be found in pa-
tients with concerning pathologies—endometrial hyperplasia,
cervical cancer, endometrial cancer—than in those with benign
processes (45.8% versus 4.8%).2A rare case of benign extensive
endometrial squamous metaplasia presenting as an echogenic
endometrial fluid collection in an asymptomatic postmeno-
pausal woman is presented.
terine fluid collection in postmenopausal women
A 63-year-old asymptomatic postmenopausal woman pre-
sented to the gynecology clinic for her annual examination. She
was morbidly obese with a past medical history significant for
diabetes, hypertension, and chronic renal insufficiency. The
patient’s Papanicolaou tests had been negative for malignancy
over the past 6 years, and she had never been on hormone
replacement therapy. She denied any episodes of postmeno-
On speculum examination, her cervix was difficult to
identify and was found to be extremely atrophic and stenotic.
On bimanual examination, her uterus could not be palpated
secondary to body habitus. Pelvic ultrasound depicted an
echogenic uterine fluid collection measuring 9.2cm·5.4cm·
7.1cm, and a thin wall was noted surrounding this complex
cystic mass which most likely represented a thin myometrium.
An irregular endometrial cavity, and a hyperechoic focus and
calcification in the region of the cervix were also noted (Fig. 1).
These findings were suspicious for malignancy. After a failed
attempt to obtain an endometrial biopsy in the office because
of her cervical stenosis, the patient underwent an attempted
cervical dilation with ultrasound guidance under general an-
esthesia, which was also unsuccessful.
The patient made an uneventful recovery, and she was
discharged on postoperative day 2. At her 6-month follow-
up, she was free from any abdominal pain.
After extensive discussion with the patient regarding the
risks and benefits of expectant management with close fol-
low-up versus hysterectomy, the patient opted to undergo
hysterectomy to obtain a definitive histologic diagnosis. She
underwent an uncomplicated total abdominal hysterectomy
Departments of1Obstetrics and Gynecology and2Pathology, New York University School of Medicine, New York, NY.
JOURNAL OF GYNECOLOGIC SURGERY
Volume 29, Number 3, 2013
ª Mary Ann Liebert, Inc.
and bilateral salpingo-oophorectomy. Intraoperatively, the
uterus was found to be enlarged and the endometrial cavity
was covered with diffuse, white raised papules and filled
with yellow particulate material. The endocervix was found
to be dilated and filled with similar particulate material. Both
ovaries were atrophic.
Microscopic study revealed extensive squamous metapla-
sia involving the entire endometrium (Fig. 2). The cervix was
noted to have a focus of condylomatous type nuclear atypia
with mild squamous dysplasia. In situ hybridization was
performed with human papillomavirus (HPV) DNA probes
for low-risk and high-risk HPV types. Hybridization for HPV
types 6 and 11 showed focal nuclear positivity in the cervix
(Fig. 3), but was negative in the endometrial cells. Detection
of high-risk HPV yielded negative results on representative
blocks from both cervical and endometrial sections.
Large-scale use of routine ultrasound screening in post-
menopausal women has enabled the detection of an increasing
number of intrauterine fluid collections in asymptomatic wo-
men. Various studies have reported a 4%–18% incidence of
intrauterine fluid collection as an incidental finding on ultra-
sound in asymptomatic postmenopausal women.2It is im-
portant to understand the implications of such a finding in
order to properly direct management. Practitioners should be
aware of the spectrum of underlying pathology and the risk of
malignancy. The broad differential diagnosis includes benign
atrophic endometrium, endometritis, endometrial polyps, and
malignant cervical and endometrial lesions.3
Breckenridge et al. reported 16 cases of uterine carcinoma
of the 17 cases of fluid collection in postmenopausal women
studied.4It is of note that all of these women were symp-
tomatic, and many had a history of endometrial or cervical
carcinoma. In contrast, recent reports have found a low in-
cidence of significant endometrial pathology associated with
the presence of intrauterine fluid. Goldstein et al. postulated
that the etiology of the fluid collection may be benign, as-
sociated with age-related atrophy and transudate attribut-
able to cervical stenosis. The same authors concluded from a
study of 30 asymptomatic postmenopausal patients with
fluid collections that the endometrial thickness is more im-
portant than the presence or amount of intrauterine fluid.
They proposed, based on this study, that if the endometrial
tissue surrounding the fluid is thin (<3mm), sampling is not
necessary, as the endometrium is inactive.5Takacs et al. re-
ported that echogenic fluid on ultrasound in postmeno-
pausal women is a more significant risk factor for
endometrial or cervical cancer than simply the presence of
commended by the authors if endometrial lining is >3mm
or if echogenic fluid is present on ultrasound.2In the case
described here, the ultrasound appearance was suspicious
for malignancy; therefore, the endometrial sampling attempt
and subsequent hysterectomy were justified.
trial lining by squamous epithelium (·40, hematoxylin
and eosin stain).
Micrograph showing replacement of the endome-
endometrial cavity with distinct echogenic fluid (arrow A).
Arrow B indicates the bladder.
Transabdominal ultrasound revealed a fluid-filled
strong positive staining for low-risk HPV types 6 and 11
Human papillomavirus (HPV) in situ hybridization:
EXTENSIVE ENDOMETRIAL SQUAMOUS METAPLASIA149
Squamous differentiation of the endometrium is uncom-
mon, and is usually found in association with endometrial
adenocarcinoma, hyperplasia, or chronic endometritis. The
squamous transformation of the endometrium has been at-
tributed to various etiologies, such as chronic trauma, repair,
irritation, inflammation, foreign materials including intra-
uterine devices, and estrogenic effects.6The involvement of
HPV in the pathogenesis of endometrial squamous meta-
plasia is currently debatable. Kinjo et al. transfected adeno-
carcinoma cells with HPV type 16, which induced squamous
metaplasia, demonstrating a possible direct causality be-
tween HPV and endometrial squamous metaplasia.7This
patient’s unique case of extensive endometrial squamous
metaplasia and coincident cervical infection with HPV 6 and
11 suggested a possible mechanism of HPV-induced squa-
mous differentiation. Furthermore, the role of chronic renal
failure, an immunosuppressive state, contributing as a pre-
disposing factor for HPV reactivation, should be considered
in this case.
Although squamous endometrial metaplasia has been re-
ported before and characterized as benign pathology in
many case reports, the clinical significance of extensive
squamous metaplasia in the endometrial cavity is less clear.
Squamous metaplasia has been implicated as a potential
precursor to primary endometrial squamous cell carcinoma
(ESCC), an extremely rare condition, often associated with
postmenopausal status, cervical stenosis, pyometra, chronic
inflammation, nulliparity, and extensive squamous endo-
metrial metaplasia. Squamous cell carcinoma of the endo-
metrium is believed to occur either through cephalad spread
of a primary cervical lesion or transformation of stem cells
positioned between the glandular basement membrane and
the endometrial columnar epithelium.8
Similar to the case described here, in the few cases reported
in the literature, the diagnosis of endometrial squamous
metaplasia was made retrospectively via histologic study of
surgical specimens.6Unfortunately, the sonographic histologic
prediction lacks specificity to differentiate extensive squamous
transformation of the endometrium from endometrial malig-
nancy in the presence of echogenic fluid. So far, knowledge of
extensive endometrial metaplasia is limited and based on a
few case reports. In light of current uncertainty about the
neoplastic potential of endometrial squamous differentiation,
surgical removal of the uterus is prudent.
Extensive endometrial squamous metaplasia is a rare
condition that can be found in postmenopausal women, and
it should be considered in the differential diagnosis of
echogenic fluid collection in the uterine cavity. Currently, the
role of HPV as a causative agent has not been completely
elucidated; however, this case supports its participation in
the pathogenesis of this condition. Given the concern for
malignancy associated with extensive endometrial squamous
metaplasia, it is reasonable to recommend surgical removal
of the uterus.
Extensive endometrial squamous metaplasia should be
included as a rare differential diagnosis in postmenopausal
women presenting with echogenic uterine fluid accumula-
tion on pelvic ultrasound.
No competing financial interests exist.
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Address correspondence to:
Ming C. Tsai, MD
Department of Obstetrics and Gynecology
New York University School of Medicine
550 First Avenue, NBV 9E2
New York, NY 10016
150 HURST ET AL.