Abstract
INTRODUCTION: In contrast to orthotopic thyroid carcinoma, primary accessory thyroid carcinoma is very rare. We herein report a case involving primary accessory thyroid carcinoma in a patient with normal ultrasonography of the orthotopic thyroid and negative (99m)TcO(4)(−) single-photon emission computed tomography (SPECT) scintigraphy. Case presentation: A computed tomography (CT) scan showed soft tissue nodules at the left anterior edge of the thyroid cartilage. To determine whether the mass was accessory thyroid tissue, (99m)TcO(4)(−) SPECT/CT was performed, and the findings were negative. However, pathological examination after resection showed that mass was a primary accessory thyroid papillary carcinoma. The 1-year follow-up ultrasound showed no lesion at the orthotropic thyroid and neck incision sites. CONCLUSIONS: This case suggests that negative (99m)TcO(4)(−) SPECT/CT imaging may not completely exclude the possibility of thyroid carcinoma. A punch biopsy or postoperative pathological examination is necessary for the diagnosis.