Papillary Thyroid Carcinoma Spreading into Branchial Cleft Cyst.

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy and it can cause cystic metastasis to the neck region. Branchial cleft cysts (BCCs) are among the most commonly encountered congenital cystic neck masses. PTC metastasis into BCC has been rarely reported in the literature. In this case report we report a patient presenting with a cystic neck mass for which fine needle aspiration biopsy was reported as benign cytology and eventually was diagnosed as PTC metastasis to the BCC. The importance of investigating the thyroglobulin levels in fine needle aspiration materials of cystic neck masses for early diagnosis of possible PTC metastasis is specifically emphasized.