Atypical Thyroiditis Following Influenza B Infection

ABSTRACT

Viral infections are known to be a predisposing factor for subacute (De Quervain's) thyroiditis. In this report, we document a novel case of thyroiditis, with an atypical presentation, following an influenza B infection. A 13-year-old previously healthy female visited the outpatient clinic complaining of right neck pain. She had been diagnosed with an influenza B infection at a local clinic 3 weeks earlier. All laboratory tests were normal. A thyroid ultrasound showed an ill-defined hypoechoic mass (1.0×0.5×1.5 cm) in the right lower thyroid, and scintigraphy of the thyroid with Technetium-99m (99m-Tc) demonstrated the normal uptake of the radiotracer. Fine-needle aspiration from the nodule showed the presence of a few neutrophils. To the best of our knowledge, this is the first case of atypical thyroiditis associated with an influenza B infection described in the literature. Influenza B infection should be considered as a possible cause of atypical thyroiditis.