Predicting Occult Retropharyngeal Lymph Node Metastasis in Surgically Treated Oropharyngeal and Hypopharyngeal Carcinoma: An Integrated Clinico-Radiological Model.

BACKGROUND: The clinical significance and true incidence of pathologically confirmed retropharyngeal lymph node (RPLN) metastasis in surgically treated oropharyngeal and hypopharyngeal squamous cell carcinoma (SCC) remain unclear, particularly regarding small, occult lesions. METHODS: We retrospectively evaluated 235 surgical patients (2005-2024). RPLN positivity was pathologically confirmed or defined by delayed recurrence within 1 year without initial RPLN treatment. Multivariable logistic regression models were developed to optimize combined multimodal imaging criteria (CT, MRI, and FDG-PET) and clinical features. RESULTS: Relying strictly on multimodal imaging findings (using a 5-mm MRI short-axis cutoff) yielded a diagnostic sensitivity of only 0.48. However, incorporating independent clinical predictors-posterior wall extension (OR: 3.50) and multiple ipsilateral Level II metastases (OR: 3.47)-into the final model at a probability threshold of 0.15 significantly expanded sensitivity to 0.74 while maintaining high specificity (0.93) and diagnostic accuracy (0.90). CONCLUSION: Combining radiological findings with clinical risk factors significantly enhances the prediction of occult RPLN metastasis, providing a reliable framework for individualized surgical planning and postoperative surveillance.