Acute transient swelling of the thyroid following fine-needle aspiration: A case series.

Acute transient swelling (ATS) of the thyroid is a rare complication following fine-needle aspiration (FNA) of thyroid nodules. We present 31 cases with 35 nodules encountered at our institute and reported in the literature, to provide further information. The incidence rate in our institute was 0.46%. Of these nodules, 74.3% (26/35) were solid, 65.7% (23/35) exhibited hypervascularity, and 77.2% (27/35) were benign or follicular neoplasms. Although most cases (87.1%, 27/31) occurred within 2 h after FNA, four patients experienced delayed ATS after 7 h to 2 days. Therefore, awareness of this complication, especially its delayed occurrence, should be raised.