Ectopic thyroid tissue in the lateral lymph nodes: A rare case and literature review

Background: Ectopic thyroid tissue in the lateral lymph nodes is a rare phenomenon that is difficult to differentiate from metastatic thyroid carcinoma, which poses a great challenge to clinical decisions and may cause unnecessary operations. Puncture eluate thyroglobulin (FNA-Tg) of fine-needle aspiration is usually significantly elevated in malignant samples, but false-positive results still exist. Case Presentation We report a patient with lymph node ectopy who was suspected to have metastatic papillary thyroid cancer (PTC) preoperatively due to an undefined thyroid nodule and a drastically upregulated FNA-Tg level in the enlarged lymph nodes. In this review, we discuss the embryonic development of ectopic thyroid tissue in the lateral lymph nodes and the application of FNA-Tg in the diagnosis of nodal metastasis. We also present the individual treatment based on FNA and ultrasound evaluation. Conclusion For patients who have isolated suspicious lateral nodes but lack direct evidence of thyroid malignancy, ectopic thyroid tissue should be considered.