A 58-year-old postmenopausal woman not on any hormonal therapy presents with rapid enlargement of a previously stable fibroid over 3 months, accompanied by new pelvic pain and weight loss. Ultrasound shows a heterogeneous mass with irregular margins, central necrosis and Doppler flow within the necrotic areas, with endometrial thickness 4 mm. The MOST likely diagnosis is:

• A Leiomyosarcoma ✓
• B Red degeneration of fibroid
• C Hyaline degeneration
• D Endometrial carcinoma invading the myometrium

Explanation

Rapid growth after menopause without exogenous estrogen, new pain, constitutional symptoms, irregular margins and necrosis with intralesional vascularity are the accepted red flags for leiomyosarcoma. Rapid growth in premenopausal women almost always reflects benign degeneration, but the same finding in a postmenopausal woman not receiving estrogen is suspicious. Hyaline and red degeneration occur mainly in reproductive years and lack these malignant imaging features. The normal thin endometrium argues against endometrial carcinoma.

Reference: Berek and Novak's Gynecology, 16th ed.

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Written and medically reviewed by the StethoPrep medical team.