Uterine leiomyosarcoma


A rare and aggressive form of uterine cancer that arises from the endometrial lining or the myometrium in the uterus.

Originates from mesenchymal tissue of embryonic origin from the mesoderm.

Uterine sarcomas account for about 4% of uterine cancers, and uterine leiomyosarcomas account for about a quarter of that 4% of cases.

Uterine sarcomas behave more aggressively and are associated with a poorer prognosis than adenocarcinomas of the uterus.

Accounts for approximately 1% of patients with uterine cancer, with an estimated annual incidence of 0.64 per 100,000 women.

Incidence of sarcoma in patients with presumed fibroids is 0.2-0.7%.

Prevalence of unsuspected sarcoma in women undergoing surgery for fibroids is approximately 1 in 352, to as low as 1 in 7,450.

Possible risk factors include long-term use of tamoxifen, prior pelvic radiation, and African American heritage.

Majority of leiomyosarcomas arise independent of pre-existing abnormalities.

May develop within a leiomyoma, and rarely leiomyomas may transform into a leiomyosarcoma.

Malignant transformation of uterine leiomyomas is more likely to occur in women from agents 40-73 years, and the prognosis for patients with such lesions is better than before patient’s with primary uterine leiomyosarcoma.

Patients with locally advanced or metastatic disease with a poor prognosis, with a median overall some viable fine of approximately 17 months after first-line treatment with a doxorubicin-based regimen.

This lesion has a high metastatic potential with 5-year overall survival rates varying between 0 and 73%.

Occurs primarily in women 40 to 60 years of age.

The most frequent presenting symptoms are abnormal vaginal bleeding and pelvic or abdominal pain.

Bleeding ranges from spotting to menorrhagia.

Patients may present with a pelvic mass.

The uterus is often enlarged clinically, and tumor may prolapse through the cervical os.

Diagnosis is usually made at the time of surgery and with findings of advanced disease.

There exists a 2-3 times higher incidence among African-American women compared to Caucasian women.

Prior pelvic irradiation is noted in 5-10% of patients.

Benign fibroid tumors often coexist in the same uterus, and they rarely, if ever, evolve into uterine leiomyocarcomas.

Not hormonally associated.

Lesion size variable, but usually 3-5cm, but can be greater than 10 cm.

About 50% of patients present with stage I disease, confined to the uterus.

Ultrasound of leiomyosarcomas he was usually are described as being a large, inhomogeneous, mass with central necrosis.

MRI examination may show lobularization with areas of necrosis and have an absence of calcifications.

PET/CT fusion scans provide anatomic and morphologic information.

Classification by the Gynecologic Oncology Group (GOG) into five categories:

Mixed homologous mullerian sarcoma-similar to endometrial stroma or myometrium

Mixed heterologous mullerian sarcoma-similar to other cell types-fat, muscle

Malignant mixed mullerian tumors (carcinosarcomas), arise from endometrial adenocarcinoma, but resemble sarcoma on histology.

Pathology indicates hypercellularity, tumor necrosis, cellular atypia, significant mitoses with >10 to 20 mitotic figures per 10 high power fields, and infiltrative borders.

Mitotic rate is the most important determinant of malignancy in uterine leiomyosarcoma.

Mitotic rate as a finding for malignancy is modified by the presence of necrosis and cytologic atypia.

Without tumor cell necrosis, the diagnosis requires moderate to severe cytological atypia and a mitotic index of >10 mitotic figures/10hpf.

In the presence of a mitotic index is < 10mitotic figures/10hpf, the chance of recurrence is less than 2-3%.

Recurrence rates vary between 45 and 75%, with a median interval to recurrence of 12-24 months.
Uterine leiomyosarcoma spreads hematogenously and often to the lungs.

Estimated five year survival is stage depending on ranges from 76% in stage I disease to 29% and stage IV disease.

In the absence of tumor cell necrosis and significant atypia, a high mitotic index is compatible with a benign clinical course.

Staging is based on surgical findings.

Associated with extensive local growth and spreads by local, lymphatic, and hematogenous routes.

Frequently associated with lung metastases, and staging requires chest imaging.

Pembrolizumib may be an alternative therapy for refractory disease.

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