Abstract
Cervical tracheal adenoid cystic carcinoma (TACC) invading the thyroid gland is very rare and easily misdiagnosed as thyroid tumor, this paper reports a TACC invading thyroid in a 33-year-old woman who had been diagnosed as a thyroid follicular tumor in right lobe of thyroid by sonography and ultrasound guided fine needle aspiration in other hospital. She accepted surgical treatment in our hospital and was diagnosed as TACC by pathology, locally involving the thyroid. This paper presents the patient's clinical data, imaging findings, pathological diagnosis, treatment process and reviews the literature of TACC mimicking a thyroid tumor.