A rare presentation of metastatic papillary thyroid carcinoma mimicking a branchial cyst in a 35-year-old female: A case report

Abstract

Introduction and importanceNeck masses are common in clinical practice, with branchial cysts presenting as painless, slow-growing lateral neck masses. Metastatic involvement of branchial cysts by thyroid carcinoma is rare. Papillary thyroid carcinoma (PTC) represents 75 %–85 % of thyroid cancers and often presents with a neck mass. This case report describes a rare presentation of metastatic PTC mimicking a branchial cyst in a 35-year-old female, emphasizing the importance of thorough evaluation. Case presentationA 35-year-old female presented with a three-year history of a slowly enlarging right submandibular neck mass. She was otherwise healthy, with no significant family or medical history. Physical examination revealed a well-defined, non-tender mass in the right anterior neck, measuring 3.4 cm. No lymphadenopathy or thyroid nodules were detected. MRI revealed an enlarged cystic lymph node. Fine-needle aspiration initially suggested a branchial cyst, but histopathology after excision confirmed metastatic PTC. Subsequent thyroid ultrasound showed a 3 mm hypoechoic nodule in the right lobe, classified as TI-RADS IV. Total thyroidectomy was planned. Clinical discussionBranchial cysts are typically benign, but this case highlights the possibility of malignancy. Excision and postoperative biopsy are essential for diagnosis, as seen in this case, leading to a total thyroidectomy plan. ConclusionNeck masses can conceal malignancies, including metastatic PTC. This case underscores the importance of thorough pathological evaluation to ensure appropriate management.