Anatomical variations of the thyroid gland: possible surgical implications.

INTRODUCTION The organogenesis of the thyroid gland in humans is often disturbed, leading to a variety of morphological variations of the gland, such as hypoplasia, ectopy, hemiagenesis and agenesis. As the morphological variations are usually diagnosed incidentally during examination for other thyroid gland diseases, the true incidence is therefore uncertain. METHODS This study was structured to investigate the gross anatomical features of the thyroid gland in 105 (88 male and 17 female) cadavers from the coastal belt of southern India, an endemic goitre region. RESULTS The pyramidal lobe was present in 61 (58 percent) male cadavers, and 52 (49.5 percent) cadavers showed the presence of the levator glandulae thyroideae. 33 percent of the specimens studied showed agenesis of the isthmus. However, the accessory thyroid tissue was found in only one cadaver. CONCLUSION This study highlights the various developmental anomalies of the thyroid gland, which forms a cornerstone to safe and effective surgery.