Accessory Thyroid Tissue and its Possible Clinical Implications

Abstract

Accessory thyroid tissue is a rare congenital anomaly due to developmental defect in thyroid gland. Accessory, aberrant, or ectopic thyroid refers to the presence of thyroid tissue in locations other than the normal anterior neck region between the second and fourth tracheal cartilages. The thyroid dysgenesis occurs due to abnormal organogenesis of the thyroid gland leading to morphological variations, such as hypoplasia, hemiagenesis and agenesis with ectopic or accessory thyroid being the most common form of thyroid dysgenesis. Here, we are presenting a case with the accessory thyroid tissue located during a routine dissection of a male cadaveric body. The accessory thyroid tissue, in the form of an oval structure about 1.5cm x 3 cm, was situated in the midline near the hyoid bone well separated from the normal thyroid gland below. The accessory thyroid tissue could be asymptomatic or it could present with any disorder affecting the main thyroid gland including malignancy. The significance of this case is to show an anatomical variation in the form of developmental defect during the organogenesis of thyroid along with its clinical implications. Thus, this report highlights the importance of knowing and understanding the normal anatomy of thyroid as well as the anatomical variant that could be immensely beneficial while diagnosing thyroid disorders or carrying out surgical procedures involving thyroid.