Papillary thyroid microcarcinoma presenting as a large cystic lymph node: A case report.

Papillary thyroid carcinoma (PTC) may deviate from the expected clinical course, posing diagnostic challenges to clinicians. The present study presents a case of longstanding swelling on the left side of the neck, initially diagnosed as a cystic lesion, which was later revealed to be metastatic thyroid cancer. A 21-year-old woman presented with a 3-year history of a neck mass that had initially been diagnosed as a likely hemangioma or branchial cleft cyst in 2019. However, subsequent scans in 2022 revealed a suspicious cyst and a thyroid nodule, which were confirmed to be PTC with metastasis to the cyst. The patient underwent a total thyroidectomy with neck dissection, followed by radioactive iodine treatment, and has had no recurrence at the 6-month follow-up. Cystic neck masses are often attributed to benign conditions such as dermoid cysts, branchial cleft cysts, epidermoid cysts, teratomas and cystic hygromas. In recent years, the rise in oropharyngeal carcinoma incidence has raised the possibility that cystic neck masses may also represent metastases from tumors in the oropharyngeal or tonsillar region. Cystic lymph node involvement in PTC with metastasis is an uncommon but significant occurrence, posing diagnostic complexities.