Etiology

• A benign, hormone-sensitive smooth muscle tumor of the uterus

• Can be submucosal, intramural, or subserosal

• Arises from a single myometrial cell (monoclonal growth) and causes:

  • Upregulation of hormone receptors, particularly estrogen and progesterone

  • Excessive production of extracellular matrix (hence "fibroids")

• Results in an overgrowth of smooth muscle cells and connective tissue (often multiple tumors)

• The myometrium also develops vascular changes (e.g., increased arterioles and venules, dilated veins).

• The most common tumor of the female genital tract.

• 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

• Obesity

• Family history

Leiomyomas are classified according to their location.

• Subserosal leiomyoma: located in the outer uterine wall beneath the peritoneal surface

• Intramural leiomyoma (most common): growing from within the myometrium wall

• Submucosal leiomyoma: located directly below the endometrial layer (uterine mucosa)

• Cervical leiomyoma: located in the cervix

• Diffuse uterine leiomyomatosis: The uterus is grossly enlarged due to the presence of numerous fibroids.

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

• Features of mass effect

  • Enlarged, firm and irregular uterus during bimanual pelvic examination

  • 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)

  • Dyspareunia