SAT-308 - Acute Thyroid Swelling after Fine-Needle Aspiration: A Case of Cracking Thyroid

Introduction: Cracking thyroid phenomenon is an acute rare complication following thyroid fine-needle aspiration (FNA) biopsy with a reported incidence of 0.1–2%. It is characterized by sudden, transient thyroid swelling with associated pain and distinctive ultrasound findings of hypoechoic, avascular septations. Symptoms typically occur within minutes to hours after the procedure and are self-limited, resolving within several hours.

Case Presentation: We present the case of a 42-year-old woman with a history significant for multinodular goiter and family history of Hashimoto’s and Graves’ disease, who underwent surveillance imaging for thyroid nodules. Thyroid ultrasound identified a 1.1 cm right thyroid nodule, TI-RADS 5. TSH was within normal limits 0.66 mIU/L. Patient subsequently underwent interventional radiology-guided FNA using direct sonographic guidance. She tolerated the procedure well without immediate complications and was discharged home.
Approximately one hour after the procedure, patient developed anterior neck pain, fullness, and swelling, prompting evaluation in the emergency department. On arrival, she was hemodynamically stable with no evidence of airway compromise. Physical examination revealed anterior neck swelling with a diffusely enlarged, soft, elastic, mobile, but markedly tender thyroid gland, without appreciable surrounding lymphadenopathy. Laboratory evaluation including CRP, ESR, and TSH were normal. Neck computed tomography demonstrated diffuse thyroid enlargement and edema with surrounding parapharyngeal and peritonsillar edema and trace fluid, consistent with the cracking thyroid phenomenon. She was treated with steroids and antihistamines and admitted overnight for close respiratory monitoring. Her symptoms improved without progression. Repeat thyroid ultrasound the following day showed expected post-biopsy mild right thyroid edema without evidence of hematoma or seroma. Though patient had residual mild right-sided neck tenderness, her symptoms improved, and she was discharged home. Cytology results were benign, consistent with follicular nodular disease.

Conclusion: Cracking thyroid phenomenon is an uncommon, but important post-FNA complication that may mimic more serious conditions such as hematoma or airway-threatening edema. Awareness of this entity with its characteristic examination and imaging findings can prevent unnecessary interventions and hospitalizations. Conservative management with close observation is typically sufficient, as symptoms resolve spontaneously within a short amount of time.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*