Atypical Subacute Thyroiditis without Thyroid Dysfunction: A Report of Two Cases.

Subacute thyroiditis (SAT) is a painful inflammation of the thyroid that causes transient thyrotoxicosis, followed by hypothyroidism and an eventual recovery. We report two atypical cases of SAT that presented with anterior neck pain, tender thyroid nodules, elevated inflammatory markers, and characteristic ultrasound findings, all suggestive of SAT, but who remained euthyroid throughout their courses. The serum thyroglobulin level increased in one case. These cases demonstrate rare euthyroid presentations of SAT despite not meeting the current diagnostic criteria for SAT established by the Japan Thyroid Association, and underscore that normal thyroid function tests do not exclude this diagnosis.