Cystic Papillary Thyroid Carcinoma: A Case Report.

Cystic nodule is an unusual presentation of Papillary Thyroid Carcinoma (PTC), seen in less than 10% of cases. Even by ultrasound, finding a thyroid cyst carries a less than 5% chance of malignancy. We present a case of a 45-year-old male, who came in for incidental finding of a palpable thyroid mass with no significant predisposing history. Thyroidectomy was done and immunohistochemical staining confirmed it to be papillary thyroid cancer. He underwent high dose radiation therapy with post therapy whole body scan showing no evidence of radioavid foci aside from the thyroid bed. The malignant potential of cystic nodule(s) should never be overlooked in certain select patients even if it carries a low chance of malignancy. The diagnosis of PTC relies primarily on the typical nuclear features, however in cases of histologic uncertainty, immunohistochemical stains such as HBME-1 may be used to help classify unusual presentations of PTC. Treatment and monitoring of Cystic Papillary Thyroid Carcinoma follows the conventional guideline on solid PTC.