Thyroid tissue in cervical lymph nodes: clinical significance, management, and review of the literature.

Abstract

Background: When thyroid tissue is found within a cervical lymph node, clinicians must distinguish between a benign ectopic inclusion (thyroidosis) and metastatic thyroid carcinoma-a distinction with major management implications. This narrative review synthesizes the available literature on benign thyroid tissue incidentally identified in cervical lymph nodes.

Methods: A focused literature search was conducted using the PubMed/MEDLINE database with an end date of April 15, 2026. Publications were included if they reported cases of benign thyroid tissue identified in cervical lymph nodes with histological or molecular confirmation, encompassing case reports, case series, or original studies.

Results: Fifteen publications were identified, covering approximately 35 to 45 cases. Patients ranged in age from 13 to 72 years (mean 46), with a marked female predominance (∼75%). Lateral cervical nodes (levels II-IV) were involved in ∼80% of cases. Histologically, benign inclusions were characterized by well-formed follicles with colloid, capsular or subcapsular positioning, and no malignant cytology. Immunohistochemical markers (e.g., HBME-1, CK19) and molecular testing (BRAF/RAS mutation analysis) were reported to be helpful in differentiating benign from malignant thyroid tissue. Associated conditions included autoimmune thyroiditis, head and neck malignancies, and postablative states. Over follow-up periods of 6 months to 10 years, no malignant transformation was observed.

Conclusion: Rigorous histological evaluation, supported by ancillary testing, enables confident diagnosis. Conservative surveillance-rather than thyroidectomy-is appropriate when malignancy has been excluded.