Morphologic Variations of the Thyroid Gland in Korean Adults

Won, Hyung sun; Chung, In hyuk

Abstract

The shape of the thyroid gland was similarly described in many anatomical text books, but we observed that the shape of the thyroid gland was very diverse in the dissecting room. This study was performed to clarify the morphologic characteristics of the thyroid gland in Koreans. One hundred sixty eight Korean adult cadavers were used for this study. It was 57.1% that the size and the location of both lobes were symmetric. The frequency of the existence of the Pyramidal lobe was 76.8%. The pyramidal lobe located in the left, right, and middle of the isthmus were 48.8%, 26.4%, and 21.7% respectively. And the pyramidal lobes located in the both sides of the isthmus were 3.1% of the cases. The thyroid gland was classified into six types. Type I in which the thyroid gland had the classical H shape and the relatively wide isthmus was observed in 31.5%. Type II in which the thyroid isthmus could be distinguished but the distance between two lobes was very short was found in 28.0%. In type III, the inferior margins of the isthmus and the lateral lobes made a straight line (29.2%). In type IV, two lateral lobes of the thyroid gland were directly fused and the isthmus was not distinguished (5.4%). In type V, the thyroid gland had no isthmus and the lateral lobes were separated (3.0%). Type VI was not belonged to five types because of its irregular shape (3.0%). The incidence of the classical thyroid gland described in the text books was 12.5% in Korean adults.