Endocrine Abstracts

Introduction: Subacute thyroiditis-SAT is an acute inflammatory disease of thyroid. It is presumed to be caused by viral infection or a postviral inflammatory process. Whatever factors initiate subacute thyroiditis, the resulting thyroid inflammation damages thyroid follicles and activates proteolysis of the thyroglobulin stored within the follicles. Papillary thyroid carcinoma typically presents as a thyroid nodule. Thyroid nodules come to clinical attention when noted by the patient; during routine physical examination; or when incidentally noted during a radiologic procedure. The diagnosis of thyroid cancer is usually made by fine-needle aspiration (FNA) biopsy. SAT associated with papillary thyroid carcinoma is very rare. Only few case reports of SAT associated with papillary thyroid carcinoma have been reported in the literature.

Case report: A 49-year-old woman was admitted to hospital. She complained of fever, fatigue, malaise, anorexia, and myalgia during the last month. She had a mild pain on both side of the neck that radiated to the jaw. Physical examination revealed diffuse enlargement and mild tenderness of the thyroid gland. There were no palpable cervical lymph nodes. The rest of the exams were normal. On thyroid US, the right lobe was diffusely hypoechogenic with low flow. A hyperechogenic nodule (2.32–1.73 cm) was found in the left lobe. On laboratory investigation: TSH was 0.01 μIU/l (normal range: 0.27–4.2 μIU/l), FT4 was 23.29 pmol/l (normal range: 12–22 pmol/l), erythrocyte sedimentation rate (ESR) was 45 mm/h (normal range: 0–20 mm/h), and C-reactive protein (CRP) was 78.38 mg/l (normal range: 0.0–5.0 mg/l). A Tc-99 imaging study was done, showing low uptake in both sides of thyroid gland. FNA of the thyroid nodule on the left lobe was performed, revealing a high suspicious for malignancy (Bethesda class V). We started oral Ibuprofene 400 mg bid, and the anterior neck pain and tenderness improved within several days. Total thyroidectomy was performed and the nodule was confirmed to be papillary carcinoma, while the rest of the tissue showed granulomatous thyroiditis.

Conclusion: The ultrasound features of the nodule in our patient were not suspicious for malignancy. Despite this we performed the FNA biopsy, which revealed a Bethesda class V, confirmed by postsurgical biopsy as papillary thyroid carcinoma. Therefore, when SAT is clinically suspected, thyroid US is a useful tool for diagnosing this disorder and it may help identify a hidden thyroid malignancy.

Keywords: Subacute thyroiditis, Papillary thyroid carcinoma.