Epidemiology

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Etiology

Predisposing factors

• Nulliparity
• Early menarche (< 10 years of age)
• Age: 25–45 years
  • Fibroids are largely found in women of reproductive age.
  • Influenced by hormones (i.e., estrogen, growth hormone, and progesterone)
  • During menopause, hormone levels begin to decrease and leiomyomas begin to shrink.
• Increased incidence in African American individuals

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Pathophysiology

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Clinical features

Symptoms depend on the number, size, and location of leiomyomas. Most women have small, asymptomatic fibroids.

• Abnormal menstruation (possibly associated with anemia): hypermenorrhea, heavy menstrual bleeding, metrorrhagia, dysmenorrhea
  • Submucosal leiomyomas are most frequently associated with significantly prolonged or heavy menstrual bleeding. The mechanism may be related to the increased total surface area as a result of the bulging uterine wall, impaired uterine wall contractility, or micro/macrovascular abnormalities.
• Features of mass effect
  • Enlarged, firm and irregular uterus during bimanual pelvic examination
    • Size can range from normal to full-term gestation
    • Differ from Adenomyosis, which shows globular, uniformly enlarged uterus that is soft but tender on palpation
  • Back or pelvic pain/discomfort
  • Urinary tract or bowel symptoms (e.g., urinary frequency/retention/incontinence, constipation, features of hydronephrosis)
• Reproductive abnormalities
  • Infertility (difficulty conceiving and increased risk of pregnancy loss)
    • Related to an obstructed uterine cavity and/or impaired contractility of the uterus.
  • Dyspareunia

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Diagnostics

Warning

Uterine leiomyomas are extremely common (affecting 70% of women) and are often found incidentally on ultrasound; do not attribute abnormal uterine bleeding to leiomyomas until other etiologies have been ruled out!

Pathology

• Macroscopic
  • Grayish-white surface
  • Homogeneous; tissue bundles on cross-section partly in a whorled pattern
  • Some leiomyomas may involve regressive changes: scar formation, calcification, and cysts
• Microscopic: Smooth muscle tissue in a whorled pattern with well-demarcated borders, consisting of monoclonal cells interspersed with connective tissue

Differential diagnostics

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Uterine leiomyosarcoma (uterine sarcoma)

Rare malignant tumor arising from the smooth muscle cells of the myometrium

• Risk factors
  • Menopause
  • Tamoxifen use
    • Because it stimulate the ER on uterine myometrium
• Uterine findings
  • Rapidly enlarging
• Pathology
  • Single lesions with areas of coagulative necrosis and/or hemorrhage
  • Cords of polygonal cells with eosinophilic cytoplasm, abundant mitoses, and cellular atypia are common.

Treatment

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