An Uncommon Presentation of Thyrothymic Thyroid Rests Presenting as a Lateral Lymph Nodal Mass

Abstract

Aim:The aim of this study is to report an uncommon presentation of the thyrothymic thyroid rests (TTR) presenting as a lateral lymph nodal mass. Background: The thyroid gland has three main embryological remnants: the pyramidal lobe, the tubercle of Zukerkandl, and TTRs. Thyrothymic thyroid rests extend along the thyrothymic ligament from the inferior thyroid pole into the mediastinum and occur in approximately 30-50% of the cases, and they can be often mistaken as lymph nodes or parathyroid glands. These embryological remnants are important as total thyroidectomy entails the removal of the thyroid gland along with all its embryological remnants to prevent recurrences and facilitate radioactive iodine therapy in malignancies. Case description: A 19-year-old female presented with a painless progressive right supraclavicular mass of 8 months duration. Contrastenhanced computerized tomography of the neck revealed a well-defined 5 × 4.5 × 2.7 cm lesion causing medial displacement of the common carotid artery and internal jugular vein and 1 × 1.2 cm nodule in the right lobe of the thyroid. Guided fine needle aspiration cytology from the thyroid nodule revealed an adenomatoid nodule (Bethesda 2), and the supraclavicular mass showed thyroid follicular cells without any lymph node architecture. A diagnosis of thyroid neoplasm with metastases in the right lateral level 4 lymph nodes was made and planned for surgical intervention. Total thyroidectomy along with a right modified radical neck dissection and central compartment node dissection was performed. Histopathology of the 5 × 7 cm right supraclavicular mass showed benign thyroid tissue without any lymph node architecture and the thyroid gland revealed a follicular variant of papillary thyroid carcinoma. Conclusion: Even though rare, TTR can present as a lateral neck swelling mimicking lateral lymph nodal mass and should be considered as a possibility. Clinical significance: As many variations are possible, a detailed embryological and anatomical knowledge regarding all these remnants is crucial for endocrine surgeons for the completeness of surgery.