Uterine leiomyosarcomas are malignant uterine tumors that arise from the myometrium. The uterus is the commonest location for a leiomyosarcoma.
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Epidemiology
Typically, these tumors present in women in the 6th decade. They account for up to one-third of uterine sarcomas but only ~8% of all uterine cancers 10.
Clinical presentation
Most commonly, patients present with abnormal vaginal bleeding, pelvic mass, and/or pelvic pain. Uncommonly, patients present with symptoms from local extension or metastases 10.
Pathology
Leiomyosarcomas mostly arise de novo 5 from uterine musculature or the connective tissue of uterine blood vessels, but can rarely arise from a pre-existing leiomyoma. The incidence of sarcomatous transformation in benign uterine leiomyomas is reported to be 0.1-0.8% 2.
The pattern of tumor spread is to the myometrium, pelvic blood vessels and lymphatics, contiguous pelvic structures, abdomen, and then distantly, most often to the lungs.
Histology can be similar to leiomyosarcomas at other sites. A leiomyosarcoma is differentiated histologically from a leiomyoma by noting the presence of infiltrative margins, nuclear atypia and increased mitotic figures.
Radiographic features
Generally, the uterus is often massively enlarged.
CT
- may show irregular central zones of low attenuation, suggesting extensive necrosis 8 and hemorrhage
- foci of calcification may be present but rare
MRI
Although it has been suggested that an irregular margin of a uterine leiomyoma on MRI is suggestive of sarcomatous transformation, this is not considered that specific.
Treatment and prognosis
Surgical resection, followed by chemotherapy and/or radiotherapy, is the treatment of choice when possible. They generally carry a poor prognosis 6.
Differential diagnosis
Consider other uterine masses such as:
- other uterine sarcomas:
- carcinosarcoma of the uterus (previously known as a malignant mixed Müllerian tumor of the uterus)
- endometrial stromal sarcoma (ESS)
- endometrial carcinoma
- large uterine leiomyoma (fibroid): especially those with myxoid degeneration or myxoid subtype 9
- uterine smooth muscle tumors of uncertain malignant potential: rare
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