Cytologic features of metastatic papillary thyroid carcinoma in cervical lymph nodes

OBJECTIVE: To elucidate the cytologic characteristics of metastatic papillary thyroid carcinoma (PTC) in cervical lymph nodes and the differences in cervical lymph nodes from those of stage I (intrathyroidal) PTC. STUDY DESIGN: Forty-seven cases of papillary thyroid carcinoma with cervical lymph node metastasis (group A) and 38 cases of intrathyroidal papillary carcinoma (group B) were included in this study. Preoperative fine needle aspiration cytology (FNAC) examination was performed on enlarged cervical lymph nodes (47 cases, group A) and enlarged thyroid nodules (13 cases, group A, and 38 cases, group B). All the cases were surgically excised and pathologically verified. The cytologic smears were reviewed and analyzed. RESULTS: The cytologic characteristics of metastatic PTC in cervical lymph nodes displayed a higher frequency of foamy macrophages (51.1% vs. 26.3%) and a lower frequency of distinct cell borders (38.3% vs. 71.1%) than those of stage I PTC. Metastatic PTC in cervical lymph nodes also had a higher frequency of cystic degeneration (44.7% vs. 5.3%) than intrathyroidal lesions. In 1 of the 47 cases with lymph node metastasis, the aspirate contained macrophages but no tumor cells. CONCLUSION: FNAC was useful in the diagnosis of metastatic PTC in cervical lymph nodes. However, because cystic degeneration appeared frequently, FNAC combined with thyroid ultrasonography to find the primary lesion is necessary in this situation.