Uterine sarcoma (leiomyosarcoma)

Definition

• Uterine sarcomas are rare malignant mesenchymal tumours of the uterus; leiomyosarcoma arises from smooth muscle cells or their mesenchymal precursors.

Classification

• Leiomyosarcoma is the most common subtype; others are low-grade and high-grade endometrial stromal sarcoma, undifferentiated uterine sarcoma and adenosarcoma.
• Carcinosarcomas are of epithelial origin and are no longer regarded as uterine sarcomas.

Occurrence & epidemiology

Risk

• Sarcoma risk: A finding clinically classified as a fibroid conceals a sarcoma in the order of approximately 0.2 to 0.3 percent.
• Risk factors: The risk increases with age and is significantly higher after menopause.
• Entities: The most common entity is leiomyosarcoma, in addition to endometrial stromal sarcoma and undifferentiated sarcoma.
• Origin: A leiomyosarcoma usually arises de novo and not from a pre-existing fibroid.

Epidemiology and risk factors

• Uterine sarcomas account for about 3–7% of all uterine malignancies.
• Incidence is higher from the age of 50 than in younger women and about twice as high in women of Afro-Caribbean descent as in white women.

Clinical features

• Symptoms are often non-specific: lower abdominal or pelvic pain, abdominal distension and, most commonly, abnormal vaginal bleeding.
• A rapidly growing presumed fibroid in a peri- or postmenopausal woman is suspicious; malignancy is often only recognised on histology.

Histology

• Leiomyosarcoma is distinguished from leiomyoma morphologically by mitoses, atypia and necrosis.
• Spindle cells in intersecting fascicles with co-expression of SMA, desmin and h-caldesmon are typical.

Diagnosis

What Raises Suspicion

• Clinical signs: Suspicious signs are rapid growth progression, growth after menopause, pain, and bleeding.
• Sonography: Sonographic indicators are inhomogeneity with necrotic zones, an indistinct border, and disordered, strong central vascularisation.
• Imaging: The crucial statement on imaging is: neither ultrasound nor MRI can reliably rule out a sarcoma.
• Laboratory tests: In terms of laboratory chemistry, there is no useful marker.

• Ultrasound and MRI cannot yet reliably distinguish a leiomyoma from a sarcoma; the diagnosis is histological.
• FIGO staging for uterine sarcomas has been adapted to the histological subtype.

Keep learning in the app

Further reading (selection)

1. Uterine sarcoma - current perspectives (Int J Womens Health 2017, PubMed Central)
2. StatPearls: Leiomyosarcoma (NCBI Bookshelf)
3. DocCheck Flexikon, Leiomyosarkom

Cross-references