DOI: https://doi.org/10.36347/sjmcr.2026.v14i04.037

Pages: 744-747

Branchial cleft cysts (BCC) are common birth defects that happen on the side of the neck, but it is very rare for these cysts to turn into cancer. Papillary thyroid carcinoma that comes from thyroid tissue that isn't supposed to be there in a BCC is very hard to spot and is not often thought about before surgery. We report a 48-year-old man who presented with a long-standing painless swelling in the lateral aspect of the neck. Fine-needle aspiration cytology (FNAC) didn't help, and imaging showed a complicated cystic lesion that looked like a BCC. The lesion was surgically excised along with evaluation of the regional lymph nodes. Histopathological examination showed papillary carcinoma coming from the cyst wall. It was characterized by arborizing papillae with fibrovascular cores, nuclear features that were typical, psammoma bodies, focal thyroid follicle formation, and metastasis to nearby lymph nodes. The patient continues to be free of disease during follow-up. This reported case illustrates the limitations of preoperative investigations in lateral cervical cystic lesions and emphasizes the significance of histopathological examination.