Morphological variations of the thyroid gland: An insight on embryological and clinicoanatomical considerations

Abstract

Background: The thyroid gland, a highly vascular endocrine gland, is composed of two lateral lobes connected by isthmus. A wide range of morphological alterations of the thyroid gland such as hypoplasia, ectopy to hemiagenesis, and genesis are common because of disturbed embryogenesis. The significance of diagnosing such extensions of the thyroid gland is crucial. It may alter the normal anatomical relationship of the thyroid gland with other adjacent cervical structures. Further, it may be confused with a tumor mass on magnetic resonance imaging and scintillation scans. Methods: The primary aim is to study the thyroid gland for gross anatomical variations (weight, height, and breadth) and secondarily to document the morphometric and congenital/developmental variation gross of the thyroid gland in 65 cadavers from the coastal belt of South India. The glands were according to the various age groups of the cadavers. Results: The mean thyroid weight was 26.01 ± 7.14 g. In males, it was 26.59 ± 6.96 g, whereas in females, it was 20.93 ± 8.98 g. The pyramidal lobe was present in 35 (53.8%), and the presence of the levator glandulae thyroideae was noted in 25 (38.48%) of male cadavers. Agenesis of the isthmus was found in 20 (30.76%). However, the accessory thyroid tissue was found in only one female cadaver. Conclusions: Our morphometric study on cadaveric thyroid glands highlights individual and ethnic variations. Knowledge of various developmental anomalies and unusual variations of the thyroid gland is of paramount importance to differentiate it from other pathologies such as autonomous thyroid nodule and thyroiditis.