Localized subacute thyroiditis presenting as a painful hot nodule

BACKGROUND: A diagnosis of subacute thyroiditis is readily considered when patients present with a particular set of typical clinical characteristics. Subacute thyroiditis sometimes presents as a solitary cold nodule; however, the presence of a hot nodule in patients with subacute thyroiditis is exceedingly rare. CASE PRESENTATION: Here, the case of a 57-year-old woman complaining of pain in the left neck and fatigue for two weeks is presented. Physical examination revealed a painful and tender nodule with a diameter of approximately 1.5 cm in the left neck, although all laboratory tests, including white blood cell count, neutrophil percentage, erythrocyte sedimentation rate (ESR), thyroid function, and thyroglobin levels, were normal. A neck ultrasound revealed a hypoechoic mass (1.5 × 0.8 cm) in the left thyroid, and thyroid scintigraphy of the left thyroid with Technetium-99 m (99 m-Tc) demonstrated a focal accumulation of radiotracer. Furthermore, fine-needle aspiration biopsy from the nodule revealed the presence of multinuclear giant cells. The patient was well; there was no cervical mass detected upon palpation following two months of prednisone treatment, and follow-up ultrasound screening and scintigraphy demonstrated the disappearance of the nodule. CONCLUSION: This case, presenting with a localized painful hot nodule, normal thyroid function, normal ESR, and normal serum thyroglobulin levels, is a rare case of subacute thyroiditis, which should be considered during differential diagnosis.