Papillary Thyroid Carcinoma in a Branchial Cleft Cyst: A Two-Case Single-Center Experience

Papillary thyroid carcinoma (PTC) arising within a branchial cleft cyst (BCC) is an exceptionally rare condition that presents diagnostic and therapeutic challenges. This study aims to describe two such cases identified in our institution and to review the relevant literature. A retrospective review of the pathology database of Unidade Local de Saúde (ULS) de Coimbra in Coimbra, Portugal, from 2015 to the present identified two such cases. Clinical, pathological, and follow-up data were analyzed, and a brief literature review was performed. The first patient, a 63-year-old man, presented with a right lateral cervical cystic mass that was surgically excised and found to be a papillary carcinoma. Subsequent total thyroidectomy revealed a microscopic focus of papillary carcinoma in the thyroid, and he received adjuvant radioactive iodine, remaining disease-free to date. The second patient, a 43-year-old man, underwent excision of a right lateral cervical BCC, with histology confirming papillary carcinoma arising within the cyst. Further evaluation demonstrated a synchronous 12 mm PTC with nodal involvement, treated with total thyroidectomy, neck dissection, and radioactive iodine, with no evidence of recurrence on follow-up. These findings highlight the need to consider malignant transformation in BCCs and underscore the importance of thorough histopathological assessment of lateral neck masses.