Abstract:

Objective: To study the clinical value of ultrasonography in diagnosis of cervical lymph node metastasis of thyroid cancer. Methods: The data of 70 cervical lymph nodes of 52 pathologically confirmed thyroid cancer patients (papillary carcinoma 43 cases, follicular carcinoma 4 cases, medullary carcinoma 4 cases, undifferentiated carcinoma 1 case) were retrospectively analyzed. All patients had ultrasonographic examination taken before operation. Gray-scale ultrasound was used to observe the morphology of lymph nodes, the internal echo, and the existence of lymph node hilum. Color doppler ultrasonography was used to detect blood flow distribution of lymph node. Lymph node length to diameter ratio <2, disappearance of lymph node hilum, calcification, cystic change, rich blood supply, and high echo were considered as suspicious character. The distribution of lymph nodes was recorded according to cervical lymph node area, and the lymph node metastasis in neck was assessed. Postoperative pathological diagnosis was taken as gold standard for evaluating the value of ultrasonography in diagnosis of lymph node metastasis of thyroid cancer in neck. Results: Seventy cervical lymph nodes were confirmed by pathology, among which 36 were thyroid cancer metastasis. The sensitivity and specificity of ultrasonography for diagnosis of cervical lymph node metastasis of thyroid cancer were 86.11% and 100%,respectively; the positive predictive value (PPV) was 100%, and negative predictive value (NPV) was 87.17%. The sensitivity of ultrasonography for diagnosing lymph node metastasis in central cervical region was 78.95%, NPV was 85.19%, lower than that of lymph node metastasis in lateral region (sensitivity 94.12%, NPV 91.67%). Cervical metastatic lymph nodes of different pathological types of thyroid carcinoma had different ultrasonographic features. Most of the metastatic lymph nodes had a length to diameter ratio <2 (28/31), disappearance of lymph node hilum (26/31), and rich blood supply (18/31). The feature of papillary carcinoma metastatic lymph nodes was diverse; calcification, cystic change and high echo were not seen in follicular carcinoma metastatic lymph nodes(0/3); medullary carcinoma metastatic lymph nodes were often calcified (3/4) and rich in blood supply (4/4), and cystic change was not seen (0/4); anaplastic carcinoma metastatic lymph nodes was rich in blood supply (1/1), and no calcification, cystic change and high echo(0/1). Conclusions: Ultrasonography is of practical value in the clinical diagnosis of cervical lymph node metastasis of thyroid cancer, which can make an accurate diagnosis and guide the establishing of appropriate treatment program. The diagnostic accuracy for metastatic lymph nodes in cervical lateral region is higher than that in central region.

Key words: Ultrasonography, Thyroid carcinoma, Cervical lymph node