Differentiating uterine adenosarcoma from endometrial polyps: MRI imaging features

This study was conducted to identify MRI features distinguishing uterine adenosarcoma from endometrial polyps and to predict the presence or absence of sarcomatous overgrowth (SO), a pathological finding linked to poor prognosis.

This multicenter retrospective study included 11 cases of uterine adenosarcoma, with 5 showing SO and 6 without, and 20 cases of endometrial polyps measuring 3 cm or greater diameter. Quantitative evaluations (tumor volume, cystic lesion size, diffusion-weighted imaging [DWI] signal ratio, apparent diffusion coefficient [ADC] value, and normalized ADC value) and qualitative evaluations (degree of hemorrhage, signal intensity on T2-weighted imaging and DWI, number of cystic lesions, degree of contrast enhancement, and tumor localization) were performed. The evaluation parameters were compared between uterine adenosarcoma and endometrial polyp groups, and between SO and non-SO subgroups within uterine adenosarcoma.

Uterine adenosarcoma had significantly larger tumor volumes (median 192,324 mm³ vs. 15,717 mm³, p < 0.001), larger cystic lesions (median 17.7 mm vs. 6.7 mm, p = 0.0074), and higher DWI signal ratios (median 1.50 vs. 1.08, p = 0.008) along with significantly lower ADC values (median 961.5 × 10^- 6 mm²/s vs. 1222.3 × 10^- 6 mm²/s, p = 0.048) and normalized ADC values (median 0.34 vs. 0.49, p = 0.001) compared to endometrial polyps. Gross hemorrhage (9/11 vs. 1/20, p < 0.001) and high signal intensity on DWI (10/11 vs. 4/20, p < 0.001) were observed more frequently with uterine adenosarcomas. No significant difference was found between uterine adenosarcomas with SO and without SO for any quantitative or qualitative evaluation parameter.

This study identified key imaging features of uterine adenosarcoma, including larger tumor volume, larger cystic lesions, gross intratumoral hemorrhage, higher DWI signal intensity, and lower ADC values. These findings can facilitate preoperative differentiation of uterine adenosarcoma from endometrial polyps.