Leiomyomas

Definition

Leiomyomas, also known as uterine fibroids, are benign smooth muscle tumors of the uterus that can cause a range of symptoms depending on their size, number, and location.

Epidemiology

• Most common benign tumor in women of reproductive age.
• Prevalence increases with age until menopause; estimated 20–40% of women aged 35–50 are affected.
• More common and symptomatic in African-American women.
• Often asymptomatic; incidental findings are frequent during imaging or surgery.

Etiology

• Exact cause unknown; multifactorial involving genetic, hormonal, and environmental factors.
• Estrogen and progesterone promote growth; tumors often regress after menopause.
• Genetic mutations, particularly MED12, have been associated with fibroid development.
• Risk factors: nulliparity, early menarche, obesity, family history, and African descent.

Pathophysiology

• Fibroids arise from a single myometrial cell undergoing clonal proliferation.
• Dependence on estrogen and progesterone for growth and vascularization.
• Can be submucosal (beneath endometrium), intramural (within myometrium), or subserosal (beneath serosa).
• May cause uterine enlargement, distortion of endometrial cavity, or pressure on adjacent structures.
• Degenerative changes (hyaline, cystic, calcific) can occur in large fibroids.