Acute suppurative thyroiditis after fine-needle aspiration causing thyrotoxicosis.

A case of thyrotoxicosis caused by acute suppurative thyroiditis after repeated fine-needle aspiration (FNA) is described. A 39-year-old woman with atopic dermatitis showed rapid enlargement of a left thyroid cyst after a third FNA. She had a high fever, painful swelling of the left thyroid, and elevated thyroid hormone levels. Ultrasonography revealed abscess formation in the left thyroid cyst. The cytologic examination of an FNA specimen showed abundant neutrophils, and culture of the aspirate yielded Staphylococcus aureus. Because antibiotic treatment for 1 month failed to improve the inflammatory findings, the patient subsequently underwent left thyroid lobectomy, which resulted in the normalization of thyroid function and the resolution of inflammation. Thyroid infection had possibly been induced by needle-track seeding, because atopic skin favors colonization by S. aureus because of local immunologic deficiency. FNA is a useful and safe technique for aspirating fluid from thyroid cysts, but special care is required in patients with atopic dermatatis to avoid bacterial infection.