International Journal of Thyroidology  2015;8(2):226-229

doi:10.11106/ijt.2015.8.2.226

A Case of Primary Papillary Thyroid Cancer That Caused Vocal Cord Palsy Arising from Thyroid Rest.

Mi Sun NA 1 ; Yong Joo LEE ; Gi Beom KO ; Jung Hae CHO

Affiliations

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Keywords

Thyroid rest; Vocal cord palsy; Thyroid cancer

Country

Republic of Korea

Language

Korean

Abstract

Thyroid rest is isolated deposit of normal thyroid tissue arising in the thyrothymic tract below the lower pole of thyroid gland. Malignant transformation of thyroid rest is very rare. We report an extremely rare case of papillary carcinoma arising from thyroid rest in a 56-year-old male. He presented with hoarseness due to vocal cord palsy. Paratracheal mass in the upper mediastinum was identified by the cause of vocal cord palsy on CT. During surgery, we identified that the mass invaded recurrent laryngeal nerve but had no connection to thyroid gland. Histopathologic examination revealed that the mass was primary papillary thyroid carcinoma and there was no evidence of malignancy in thyroid gland. The post-therapeutic I-131 whole body scan detected several focal hot uptake in lung and mediastinum, suggesting distant metastasis. We should have knowledge of developmental variations of thyroid gland such as thyroid rest and its malignant transformation.