Abstract
INTRODUCTION AND IMPORTANCE: Neck 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 PRESENTATION: A 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 DISCUSSION: Branchial 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. CONCLUSION: Neck masses can conceal malignancies, including metastatic PTC. This case underscores the importance of thorough pathological evaluation to ensure appropriate management.