Table 1.

Comparison between leiomyoma and uterine leiomyosarcoma.

Features	Uterine Leiomyoma	Uterine Leiomyosarcoma
Clinicopathologic	Similarities Abnormal uterine bleeding Pelvic pressure Pelvic mass Differences No growth after menopause in the absence of hormonal therapy Commonly exists in multiples	Similarities Abnormal uterine bleeding Pelvic pressure Pelvic mass Differences Growth after menopause Commonly exists as a solitary mass
Tissue Origin	Similarities Originates in the myometrium of the uterus Differences Cell type: MMSCs	Similarities Originates in the myometrium of the uterus. Differences Cell type: unknown
Genetic Abnormality	MED12 and HMGA2 mutation	Complex karyotypes and aneuploids
Morphology	Similarities May be a solitary uterine tumor Express progesterone, estrogen, and androgen receptors Myxoid features of degenerated LM can be seen in LMS Differences Sharply demarcated or defined border Variants may exhibit increased cellularity and infarct-type necrosis	Similarities May be a solitary uterine tumor Express progesterone, estrogen, and androgen receptors Myxoid features of degenerated LM can be seen in LMS Differences Invades adjacent myometrium Extensive areas of tumor cell necrosis and hemorrhage, hypercellularity, and severely atypical nuclei with >15 mitotic figures per 10 high-power fields
Behavior, Onset, Incidence	Similarities Incidence increases with age Common at age >40 More prevalent in Black women Differences Common and benign More common in reproductive age No growth after menopause Low mortality rate May be asymptomatic	Similarities Incidence increases with age Common at age >40 More prevalent in Black women Differences Rare and malignant More common in late perimenopause and menopause Growth after menopause High mortality rate Rarely asymptomatic

Note: LM: leiomyoma; LMS: leiomyosarcoma.