Diagnostic ultrasound ( PDFDrive )

540 PART II Abdominal and Pelvic Sonography
Leiomyomas: Sonographic Features
Hypoechoic or heterogeneous solid mass, occasionally
hyperechoic
Round or oval shape
Distortion of external uterine contour or endometrium,
depending on size and location
Attenuation or shadowing
Calciication
Cystic areas from degeneration or necrosis
Fibroids may have variable appearances (see Fig. 15.11, Video
15.3) but most oten appear as well-deined, spherical to ovoid,
solid masses that are hypoechoic compared with normal myometrium.
hey are frequently heterogeneous and tend to produce
mass efect on adjacent structures depending on size and location.
Leiomyomas may attenuate sound deep to the entire mass, but
also commonly have bandlike areas of shadowing originating
from nonhyperechoic areas within the mass, termed “refractory
shadowing.” 77 Calciication occurs in a minority of leiomyomas.
he calciication is usually in one or more focal areas and has
associated acoustic shadowing. Less frequently, rim calciication
may occur and in general is seen ater hemorrhagic degeneration
or ater uterine artery embolization (UAE). Occasionally,
leiomyomas are isoechoic or hyperechoic compared with myometrium.
When one encounters a hyperechoic leiomyoma, a
lipoleiomyoma should be considered, 78,79 although it is likely
that not all hyperechoic leiomyomas are lipoleiomyomas. he
fat in a lipoleiomyoma is probably due to adipocyte diferentiation
rather than a degenerative change. 80 Lipoleiomyomas are most
frequently noted in postmenopausal women 78 and usually have
a benign clinical course. 80,81
Uterine leiomyomas occasionally undergo various forms of
benign degeneration. Many types of degeneration are not evident
sonographically and may be better detected on MRI. 82 Cystic
spaces within a leiomyoma usually indicate cystic degeneration
but may also be seen with myxoid degeneration. Hyaline,
hemorrhagic, and hydropic degeneration are usually diicult to
diagnose by ultrasound. Hemorrhagic degeneration may not
produce any change in appearance, although homogeneity, a
hyperechoic rim, and lack of detectable low by Doppler imaging
have been described. 76 In a patient with acutely degenerating
ibroid (typically during rapid growth in pregnancy or as a result
of UAE), pain will usually be localized to the ibroid(s) undergoing
degeneration, and thus the diagnosis can be suggested during
the sonographic examination, even if the sonographic appearance
of degeneration is not yet evident.
Fortunately, the vast majority of myometrial masses are due
to leiomyomas. here are other uncommon forms of myometrial
neoplasms, such as cellular leiomyomas and smooth muscle
tumors of uncertain malignant potential (STUMPs), but we
are not aware of any speciic sonographic features to diagnose
such entities. 76 Rarely, leiomyomas have unusual growth patterns
such as intravenous leiomyomatosis, disseminated peritoneal
leiomyomatosis, benign metastasizing leiomyomas, and parasitic
leiomyomas; the leiomyomas in these rare entities have a
similar appearance to the more usual leiomyomas but are in
vastly diferent locations. 76,82
Ater noninvasive treatment with UAE most ibroids remain
hypoechoic, although cystic change or increased echogenicity
occasionally occurs; diminished or absent low on Doppler
imaging is expected. 83 Tubular hyperechoic structures thought
to be due to thrombosed uterine artery branches have been
described ater UAE. 84 Echogenic foci due to gas may occur in
leiomyomas as a normal inding ater UAE, and clinical assessment
is needed to help distinguish this from a pyomyoma. 82 Submucosal
ibroids may prolapse and thus a mass may be seen in the
endometrial cavity, cervix, or vagina. 85 Little has been reported
about the appearance of leiomyomas ater MRI-guided focused
ultrasound ablation.
Leiomyosarcoma
Uterine sarcomas are uncommon. Although some forms of
uterine sarcoma arise in the endometrium, the more common
leiomyosarcomas arise in the myometrium. Risk factors for
leiomyosarcoma include pelvic irradiation, tamoxifen, and rare
genetic syndromes. 72 Unfortunately, it is diicult to diagnose
leiomyosarcomas by ultrasound or other imaging modalities
because their appearance and growth rate overlap with the much
more common leiomyomas. Other than evidence of metastasis,
no currently known imaging feature is reliably predictive.
Leiomyosarcomas tend to be large and heterogeneous and to
have cystic change (Fig. 15.12), but such changes are also common
in leiomyomas. 82 Doppler imaging has not proven reliable. Rapid
growth, particularly in a postmenopausal patient, has been
considered a worrisome sign for leiomyosarcomas but “rapid”
is not well deined and the usefulness of rapid growth is unclear.
Diagnosis of leiomyosarcoma by MRI is also challenging, although
difusion-weighted imaging may be helpful. 86,87 Serum lactate
dehydrogenase levels may be helpful for diagnosis of
leiomyosarcoma. 87a,87b
Adenomyosis
Adenomyosis is a benign condition wherein endometrial glands
and stroma are present in the myometrium. In general, the histologic
diagnosis of adenomyosis requires the presence of endometrial
glands or stroma to be located more than 2.5 or 3 mm away from
the outer edge of the endometrium. 88,89 It may cause pain, abnormal
vaginal bleeding, or infertility, although some patients are asymptomatic.
he prevalence of adenomyosis is uncertain; there are
widely varying estimates from 5% to 70%. 90 Adenomyosis and
Adenomyosis: Sonographic Features
Diffuse, sometimes globular-shaped, uterine enlargement
Diffusely heterogeneous myometrium
Asymmetrical thickening of myometrium
Indistinct hypoechoic areas
Myometrial cysts
Poor deinition of endometrial-myometrial border
Focal tenderness elicited when scanning over the uterus
Subendometrial echogenic linear striations
Subendometrial echogenic nodules