Localized painful giant-cell thyroiditis without inflammatory signs in a euthyroid patient followed by serial sonography.

We describe a patient with localized painful giant-cell thyroiditis. A 45-year-old woman noticed a tender lump in the left side of the neck. Sonography of the thyroid revealed diffuse swelling of the left lobe with irregular hypoechoic areas. Three months later, the tender swelling subsided, and the hypoechoic areas disappeared without any treatment. There were never any systemic signs of inflammation or thyroid dysfunction. Atypical localized subacute thyroiditis was considered to be the most probable diagnosis based on fine-needle aspiration cytology and serial sonography. Serial sonographic evaluations are useful to avoid unnecessary surgery.