Risk Factors and Prognosis of Retropharyngeal Lymph Node Metastasis from Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) metastasis to the retropharyngeal lymph node (RPLN) is rare but clinically significant due to its implications for patient prognosis and treatment strategies. This study aims to investigate the risk factors and prognosis associated with this uncommon metastasis.

We conducted a retrospective case-control study involving 34 PTC patients with RPLN metastasis treated between January 2007 and December 2017. These patients were compared with a control group of 68 PTC patients with lateral lymph node metastasis but no RPLN involvement, selected randomly from those treated between January 2010 and December 2012. Inclusion criteria included confirmed PTC diagnosis, documented RPLN metastasis, and comprehensive follow-up data. Data collection encompassed preoperative examinations, surgical treatments, and follow-up outcomes. Statistical analyses were performed using SPSS 19, with survival analysis conducted via the Kaplan-Meier method and the Log-rank test for single-factor analysis.

Among the research group, only 7 patients were initially treated, while 27 had a history of thyroidectomy. The average time from initial thyroidectomy to RPLN metastasis was 93.1 months. Imaging methods such as CT scan, MRI, and 131I-SPECT/CT demonstrated high sensitivity in detecting RPLN metastasis. The 5-year survival rate was 77.5%. Patients with RPLN metastasis exhibited higher rates of tumor dedifferentiation, distant metastasis, and higher central lymph node density compared to the control group.

RPLN metastasis in PTC, though rare, should be considered during follow-up, particularly for patients with tumor dedifferentiation, glandular dissemination, and distant metastasis. Routine ultrasonography may miss these metastases; hence, periodic CT scans, MRI, or 131I-SPECT/CT are recommended. Despite the advanced disease stage at diagnosis, active treatment, including surgical resection via the transcervical approach, can result in a favorable prognosis. Metastasis to lymph nodes below the hyoid plane indicates a poorer prognosis.