Occult sentinel lymph node metastasis detected by intraoperative ex vivo high-frequency ultrasound in clinically early-stage cervical cancer: a case from the prospective RHINOCERUS study.

Accurate nodal staging in early-stage cervical cancer remains challenging. Although preoperative imaging is mandatory in the preoperative workup, its limited sensitivity for small-volume disease, together with the suboptimal performance of intraoperative frozen section, may result in undetected lymph node metastases. We report a case from the ongoing RHINOCERUS study (NCT06906705) exploring the feasibility of intraoperative high-frequency ultrasound for sentinel lymph node evaluation. A patient with cervical cancer clinically staged as FIGO 2018 stage IB1, with no evidence of nodal involvement at preoperative imaging, was selected for radical hysterectomy with sentinel lymph node biopsy. After surgical excision, sentinel lymph nodes were intraoperatively assessed ex vivo using a 33 MHz high-frequency linear ultrasound probe and classified according to standardized ultrasound criteria. Ultrasound classified one sentinel node as malignant (LN5) and the other as probably malignant (LN4). Histopathological examination subsequently confirmed metastatic involvement in both sentinel lymph nodes. Qualitative comparison demonstrated concordance between ultrasound features and the histopathological correlates. These preliminary findings suggest that high-frequency ultrasound may provide real-time intraoperative morphological assessment of lymph nodes. Intraoperative identification of nodal metastases could inform surgical decision-making. Further prospective evaluation is ongoing to define its diagnostic accuracy and clinical applicability.