Objectives/hypothesis: The objectives were to quantify the incidence of clinically unsuspected thyroid tissue in cervical lymph nodes encountered during neck dissection in patients with head and neck carcinoma, to describe the location and histological aspect of these inclusions, and to assess their clinical significance.
Study design: Retrospective study.
Methods: The histological records of 1123 neck dissections in 752 patients with head and neck carcinoma were reviewed. In cases with thyroid inclusions, the pathological diagnosis was reviewed and an immunohistochemical study against thyroglobulin and calcitonin was carried out.
Results: Clinically unsuspected thyroid tissue was found in lymph nodes in 11 of the 752 patients with head and neck carcinoma treated with neck dissection. In five cases, the thyroid inclusion was compatible with a metastases of an occult papillary thyroid carcinoma. In the other six cases, a collection of thyroid follicles without malignant characteristics was found beneath the lymph node capsule. These latter cases were considered benign thyroid inclusions. A thyroidectomy was performed in three of the patients with lymph node metastases of the papillary carcinoma. An occult papillary carcinoma was found in only one case. The other two patients had been treated previously with radiotherapy for an early-stage glottic carcinoma. Immunohistochemical study did not find calcitonin-positive cells within the benign thyroid inclusions. After a follow-up period ranging from 1.2 to 8.2 years, no patient had any kind of local, regional, or distant relapse related to the thyroid disease.
Conclusion: The incidence of unsuspected thyroid tissue in lymph nodes of patients with head and neck carcinoma treated with neck dissection was 1.5%. Both lymph node metastases of a papillary carcinoma and benign thyroid inclusions were found. The study results suggest that the incidental finding of thyroid tissue in the lymph nodes during a neck dissection in patients with head and neck carcinoma does not necessarily indicate the need for aggressive therapy.