A 50-year-old woman undergoes hysterectomy for a presumed uterine leiomyoma. Histology shows a smooth muscle tumor with moderate nuclear atypia, tumor cell necrosis, and 12 mitoses per 10 high-power fields. According to the Bell criteria, what is the correct diagnosis?

• A Leiomyosarcoma ✓
• B Smooth muscle tumor of uncertain malignant potential (STUMP)
• C Leiomyoma with bizarre nuclei
• D Intravenous leiomyomatosis

Explanation

Per the Bell criteria, a smooth muscle tumor with any two of the three features (moderate-to-severe atypia, tumor cell necrosis, and >=10 mitoses/10 HPF) is classified as leiomyosarcoma. This tumor has all three features, making leiomyosarcoma the definitive diagnosis. The triad of coagulative tumor cell necrosis, diffuse moderate-to-severe atypia, and >=10 mitoses/10 HPF are the diagnostic criteria. Leiomyoma with bizarre nuclei lacks tumor cell necrosis and has <10 mitoses.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.