Benign smooth muscle neoplasm of uterus

Synonym: Fibroid

Ultrasound (transabdominal and transvaginal): Study of choice; supplemented by 3D US and saline-infused sonohysterography

Circumscribed mass, hypoechoic to myometrium

Posterior acoustic shadowing, even without associated calcifications

Variable location: Submucosal, intramural, subserosal, intracavitary, pedunculated, cervical, or broad ligament

Bulky uterine enlargement from large or multiple leiomyomas

Masses appear heterogeneous when there is cystic degeneration or hemorrhage

Size: Extremely variable, subcentimeter to > 10 cm

MR

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  Low T2 signal from smooth muscle proliferation

  
  
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  Variable enhancement on postcontrast imaging

  
  
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  High signal on T1WI if hemorrhage; high signal on T2WI if cystic degeneration

Submucosal: Mass effect on endometrium, may obstruct endometrial canal if intracavitary

Subserosal: Distorts uterine contour, especially if large

Pedunculated: At risk for torsion with vascular connection visible on color Doppler

Color Doppler: Peripheral vascularity

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  Ischemia/degeneration: Decreased or absent color flow

  
  
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  Cervical: Unlike nabothian cyst, will have internal blood flow

Vascular stalk helps characterize pedunculated leiomyoma

Broad ligament: May be confused for solid ovarian mass, unless ovary identified separately

Lipoleiomyoma: Variant of leiomyoma with variable amount of fat

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  May be hyperechoic due to significant fat component

Saline-infused sonohysterography helpful in characterizing submucosal fibroids

Adenomyosis

Focal myometrial contraction

Leiomyosarcoma

Uterine duplication

Increase in size and frequency with age

25-30% incidence in United States

Symptoms primarily related to leiomyoma location, size, &/or growth: Heavy bleeding, pelvic pressure, pain

Degeneration can cause acute pelvic pain

Can undergo rapid growth during pregnancy

Submucosal: Dysfunctional uterine bleeding

Subserosal: Bulk symptoms, including urinary urgency &/or constipation

Pedunculated: Can have severe pain from torsion

Cornual leiomyoma may cause tubal obstruction

For bulk symptoms or bleeding, management includes uterine artery embolization, myomectomy, or hysterectomy

If greater than 50% of submucosal leiomyoma is within endometrial cavity, will require hysteroscopy for removal

If borders are not well delineated, consider adenomyosis

SIS to evaluate submucosal leiomyomas

MR prior to uterine artery embolization, and to evaluate multiple or complex leiomyomas

Consider malignant form if rapidly growing uterine mass in postmenopausal woman

Cine clips are useful to differentiate from adenomyosis