Neoplastic pericarditis represents approximately 5%-7% of the cases with acute pericarditis and is rarely the initial manifestation of malignancy. The most common cause is lung cancer, followed by breast cancer, lymphomas, leukemia, and esophageal cancer. Neoplastic pericardial disease is extremely rare in thyroid cancer, especially as the first manifestation. Here, we present a papillary thyroid carcinoma that was manifested with pericarditis and cardiac tamponade in a 49-year-old female.