Clinical Pearls & Morning Reports

Published May 24, 2017

What are some of the features of uterine leiomyosarcoma?

Sarcomas account for 3 to 7% of uterine cancers, and leiomyosarcomas represent the most frequent histologic subtype of sarcomas. Leiomyosarcomas most commonly occur in postmenopausal women, and the prevalence of these tumors increases with age. Read the latest Case Record of the Massachusetts General Hospital.

Clinical Pearls

Q. Can adenomyosis manifest as a uterine mass?

A. Adenomyosis typically affects premenopausal women and is associated with pain, dysmenorrhea, and vaginal bleeding. It is usually associated with uterine enlargement. On imaging studies, the interface between the endometrium and the myometrium is usually abnormal, and the myometrium often has a heterogeneous echotexture. Adenomyosis may occasionally be manifested by a mass in the uterus, which is known as an adenomyoma.

Q. Where do uterine carcinosarcomas typically arise?

A. Uterine adenocarcinomas typically arise in the endometrium and are associated with vaginal bleeding. Uterine carcinosarcomas are composed of cancerous epithelial tissue with a malignant mesenchymal component; these cancers usually progress rapidly and are associated with early metastatic spread.

Q: What are some of the features of uterine leiomyosarcoma?

A: Uterine sarcoma is a rare diagnosis. The leiomyosarcoma variant is the most common malignant mesenchymal tumor of the uterus, with an estimated 1000 cases diagnosed in the United States in 2016. Leiomyosarcomas are usually solitary and measure an average of 10 cm in diameter. The cut surface of the tumors is fleshy and tan and often has foci of hemorrhage and necrosis. The tumors may be well circumscribed or may infiltrate the surrounding myometrium. Uterine leiomyosarcoma usually arises independently, although it can arise in association with a benign leiomyoma. There are three features in uterine smooth-muscle tumors that are characteristic of cancer: prominent moderate-to-severe cytologic atypia, sufficient mitotic activity (i.e., ≥10 mitoses per 10 high-power fields examined), and tumor-cell necrosis. At least two of these three features are generally needed to establish a diagnosis of leiomyosarcoma.


Figure 1. Pelvic Ultrasound Images.


Figure 2. Hysterectomy Specimen.

Morning Report Questions

Q: Can uterine leiomyosarcoma be distinguished from leiomyoma using imaging alone?

A: Distinguishing uterine leiomyosarcoma from leiomyoma is challenging, because there are no reliable signs, symptoms, or diagnostic tests. A leiomyoma is typically a hormonally responsive tumor that is stimulated by estrogen, and growth is relatively uncommon after menopause. The presence of a rapidly growing leiomyoma, particularly in a postmenopausal woman, is often worrisome for leiomyosarcoma. Transvaginal ultrasonography and magnetic resonance imaging (MRI) are the most commonly used imaging techniques in evaluating for leiomyosarcoma. Irregular tumor margins, cystic changes, and specific signal characteristics on MRI have been associated with leiomyosarcoma; however, both transvaginal ultrasonography and MRI have relatively poor accuracy in discriminating leiomyosarcoma from leiomyoma. Endometrial biopsy also has a relatively low sensitivity for the detection of leiomyosarcoma. Definitive diagnosis of uterine leiomyosarcoma typically relies on surgery, usually hysterectomy.

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