Role of imaging

The role of imaging is to confirm the diagnosis of uterine leiomyoma and to differentiate leiomyomas from other causes of uterine enlargement or pelvic masses such as ovarian or endometrial based masses, adenomyosis, serosal implants and lymphadenopathy. In addition, the number, size, and location of leiomyomas must be assessed. This is particularly important in the symptomatic, infertile, or pregnant patient. Possible complications including benign degeneration should be recognized. Signs suggestive of malignant transformation must be evaluated. Imaging is useful in preoperative mapping, particularly in the setting of uterus-sparing procedures and for therapy monitoring.

General histology

Uterine leiomyomas are well-circumscribed, benign smooth muscle neoplasms with various amounts of fibrous connective tissue. Leiomyomas may be single or, more frequently, multiple. Uterine leiomyomata are estrogen-sensitive neoplasms that occur in 20–30% of reproductive-aged women. Leiomyomas regress during anovulatory cycles as a result of unopposed estrogen stimulation. As leiomyomas enlarge, they may outgrow their blood supply, resulting in ischemia and degeneration characterized as hyaline, cystic, myxomatous, fatty, or hemorrhagic. Rapid increase in size of leiomyomas in a postmenopausal patient should raise the possibility of sarcomatous change.

Classification by location

Leiomyomas originate from the uterine corpus in the vast majority of cases; however, rarely (3–8%) they can arise from the cervical region. Uterine leiomyomas are categorized with respect to their location (subserosal, intramural, submucosal).