Acute transient thyroid swelling after fine-needle aspiration biopsy: A case report of a rare complication and a literature review

Fine-needle aspiration biopsy (FNAB) is a safe and effective thyroid examination method with rare complications. Herein, we report a rare case of acute transient thyroid swelling that occurred after ultrasound-guided FNAB. The patient experienced acute pain with rapid thyroid swelling. Ultrasound imaging revealed a nodule with a linear, hypoechoic, and "patch-like" appearance, indicating edema without hemorrhage. After receiving anti-anaphylaxis and detumescence therapy for 1 day, the swelling regressed. Acute transient thyroid swelling is an extremely rare event that occurs shortly after FNAB and may frighten patients; therefore, clinicians should be aware of this complication in this context.