A 48-year-old woman presents with abnormal uterine bleeding. Hysteroscopy and curettage reveals a uterine tumour. Histopathology shows spindle-shaped cells with >10 mitoses per 10 high-power fields and moderate nuclear atypia, without a distinct epithelial component. The MOST likely diagnosis is:

• A Endometrial adenocarcinoma
• B Carcinosarcoma (malignant mixed Müllerian tumour)
• C Endometrial stromal sarcoma
• D Uterine leiomyosarcoma ✓

Explanation

Leiomyosarcoma is the most common uterine sarcoma and arises from smooth muscle. The diagnostic criteria include ≥10 mitoses per 10 high-power fields (HPFs), significant cytological atypia, and coagulative tumour cell necrosis. The purely mesenchymal (spindle cell) histology without an epithelial component distinguishes it from carcinosarcoma. Endometrial stromal sarcoma has low mitotic activity (<10/HPF in low-grade variety) and tongue-like infiltration of the myometrium.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

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Written and medically reviewed by the StethoPrep medical team.