Metastatic Papillary Thyroid Carcinoma
Cervical lymph nodes are commonly involved in papillary thyroid carcinoma (PTC) and sometimes are the first manifestation of the disease. About one-third of patients with PTC present with cervical lymphadenopathy without a thyroid mass. Careful examination will reveal cervical nodal metastases in almost 80% of PTC cases. The lymph node involvement is usually ipsilateral, but 10% of cases show bilateral metastases. After cervical lymph nodes, the next group to be involved is mediastinal (5% of cases). The lymph nodes may not be clinically apparent as they may not enlarge and may retain normal consistency. The metastatic deposits may replace the entire lymph node, although usually there is a rim of residual lymphoid tissue. When small, the metastatic deposits are found within the subcapsular sinuses. The nodal metastases frequently undergo cystic changes and can mimic a branchial cleft cyst.