Faculty Bibliography

Introduction: Ultrasound guided FNA is important in guiding management of thyroid nodules. Complications are usually limited to localized discomfort, bruising, or minor hematomas. At our institution, cytopathologists perform 600 - 900 ultrasound guided thyroid FNAs yearly. Acute transient thyroid swelling is a rare complication. A diffuse swelling of the entire thyroid occurs after a biopsy with a characteristic "cracked appearance" on ultrasound imaging. Cytopathologists and radiologists need to recognize this phenomenon and terminate the procedure. Materials and Methods: We conducted a retrospective review of our pathology and radiology database from 2004 -2015 for documented transient thyroid swelling. We reviewed patient demographic information, thyroid antibody and function studies, allergies/ medical history, and pathology diagnosis (Table 1). Results: We identified 7 cases of transient diffuse swelling of the thyroid from 6,175 thyroid FNAs. In all cases, the thyroid architecture becomes obscured by diffuse enlargement of the thyroid with an internal "cracked appearance" without skin swelling or hematoma (Figure 1). Imaging shows two to three times increase in overall thyroid volume. Patients usually reported acute pain that resolved shortly after the procedure was ceased and ice pack was applied. Post-procedural observation showed resolution of swelling. Patients had no known latex allergy or prior adverse reactions to needles. In most cases, the patients tolerated initial FNA without complications. One patient had a repeat FNA with Benadryl premedication without adverse complications but it is unclear whether there was a preventative effect. Conclusion: This benign, transient reaction should be distinguished from severe complications such as anaphylaxis and hemorrhage. We hypothesize that this event is attributable to intra-thyroidal edema since no discrete hematoma is seen on imaging. Pre- and post-procedural ultrasound imaging is essential for detecting change in thyroid architecture. Recognition of this rare event is crucial when performing ultrasound guided thyroid FNA. (Figure Presented)