Thyroid Isthmus Agenesis in a Patient with Papillary Carcinoma of Thyroid.

Thyroid gland is the largest of all endocrine glands. It is composed of two lobes. These two lobes are joined by an isthmus and this resemble the letter "H". A wide range of morphological variations and developmental anomalies of the thyroid gland like hypoplasia, ectopy, hemiagenesis, and agenesis have been reported in literature. Out of these, the incidence of agenesis of the thyroid isthmus is rare, and very few cases have been reported. In our report, 28 year old male patient was found with agenesis of thyroid isthmus with papillary carcinoma in the right lobe of thyroid. During the operation it was seen that the right and left thyroid lobes were independent from each other and isthmus was absent. We will present a case of thyroid isthmus agenesis and discuss the clinical importance and the incidence of this case.