Differentiating Endometrial Stromal Sarcoma from Cellular Leiomyoma Based on a Nomogram Integrating Multimodal MRI and Clinical Data

This retrospective, dual-center study developed and validated a nomogram combining quantitative ADC metrics and MRI features to differentiate endometrial stromal sarcoma (ESS) from cellular leiomyoma (CL). A total of 155 women were included (ESS: n = 57, CL: n = 98), divided into a derivation cohort (n = 111) and an external validation cohort (n = 44). All participants underwent preoperative contrast-enhanced pelvic MRI. A nomogram incorporating irregular margin, cystic areas, and mean ADC value was constructed. The model achieved an area under the curve (AUC) of 0.828 (95% CI: 0.742–0.911) in the derivation cohort and 0.873 (95% CI: 0.768–0.977) in the external validation cohort. Sensitivity and specificity were 78.5% and 87.9% in the derivation set, and 87.5% and 75.0% in the validation set, respectively. In conclusion, this nomogram provides a simple, accurate, and non-invasive tool for the preoperative differentiation of ESS from CL and has been implemented as a user-friendly web-based calculator to facilitate clinical use.