Suspicious sonographic and cytological findings in patients with subacute thyroiditis: Two case reports.

We here report on two cases of suspicious cytological findings upon ultrasound (US)-guided fine-needle aspiration (US-FNA) in patients with subacute thyroiditis (SAT). A 46-year-old woman who underwent US-FNA for a suspicious thyroid nodule in the right lobe at a local clinic was referred to our hospital for surgical treatment. Based on the cytology results, total thyroidectomy was performed. The histopathology findings confirmed the presence of SAT in the right lobe and absence of thyroid malignancy. A 40-year-old woman with a thyroid nodule in the left lobe with suspicious cytological findings upon US-FNA was referred to our hospital for surgical treatment. However, neck US revealed typical sonographic findings of SAT. On follow-up US 3 months later, near complete disappearance of the typical sonographic findings of SAT was observed, while a hypoechoic solid thyroid nodule in the left upper lobe was clearly visualized. Accordingly, US-FNA was performed for the hypoechoic thyroid nodule. Papillary thyroid carcinoma was suspected on the basis of the cytology findings; histopathologically, SAT was confirmed in both thyroid lobes and a papillary thyroid carcinoma was confirmed in the left lobe.