A rare case of hyperfunctioning papillary carcinoma of the thyroid gland

We report a rare case of hyperfunctioning papillary carcinoma of the thyroid. A 32-year-old man was referred to our hospital for the treatment of a painless mass in the left neck, which had been detected on routine physical check-up. Cervical ultrasonography and computed tomography showed a solid tumor with calcification in the left lobe of the thyroid gland. Serum examinations demonstrated hyperthyroidism with a high level of thyroglobulin. Fine needle aspiration biopsy revealed a cytological diagnosis of class II. Tc-99m scintigraphy showed a hot nodule in the left lobe, which implied that the tumor was a hyperfunctioning thyroid tumor. Left lobectomy of the thyroid gland was performed to treat the hyperfunctioning tumor. Postoperative pathological examinations revealed a follicular variant papillary carcinoma. Postoperative thyroid function became within the normal range. Although hyperfunctioning thyroid carcinomas are rare, it is important to correctly diagnose them and to perform appropriate surgical interventions.