Acute transient thyroid swelling following fine-needle aspiration: a case series and a systematic review.

Background: Acute transient thyroid swelling (ATTS) is a rare complication of fine-needle aspiration (FNA) of thyroid nodules. Most cases were in spontaneous remission. However, it is fatal in rare cases. However, there are few literature reports, so it is of great significance to improve the clinical understanding of ATTS. Therefore, this study aimed to present 10 institutional cases and a systematic review of 18 literature cases to delineate clinical features, imaging findings, and management approaches. Methods: Twenty-eight clinical cases (10 cases from institutional archives and 18 cases from literature search) were included in the retrospective analysis. Data collection continued until August 1, 2024. Results: ATTS following FNA is a rare complication. Among the 28 total cases (10 institutional, 18 literature), 89% were female. Bilateral goiter occurred in 71%. Symptoms typically emerged within one hour following FNA, resolving spontaneously within 24 hours in 79% of cases. Neck pain/swelling (54%) was common; severe complications (dyspnea, cardiac arrest) were rare (3%). Ultrasound revealed unilateral/bilateral goiter with linear/patchy hypoechoic areas and preserved vascularity. Non-pharmacological management sufficed for most patients. Conclusions: ATTS following FNA is self-limiting, with distinct ultrasound findings. Clinicians should prioritize airway management in severe cases and avoid unnecessary interventions in mild presentations.