Hemiagenesis of the thyroid gland

Abstract

Thyroid hemiagenesis is a rare developmental anomaly. This congenital abnormality is usually discovered upon investigating thyroid disorders primarily through thyroid imaging studies. Coupled with its sensitivity, ultrasonography remains as the non-invasive investigation of choice in establishing the diagnosis. A thyroid-stimulating hormone test may similarly provide confirmatory evidence of an absent thyroid lobe which may occasionally involve the isthmus of the gland as well. Surgical exploration performed in relation to a pathological entity affecting the remaining thyroid gland as illustrated in our patient is another means of establishing the diagnosis. Various other abnormalities have been described in relation to thyroid hemiagenesis. We report a case of hemiagenesis of the thyroid gland in a young female who presented with a benign nodule affecting the thyroid isthmus. We believe this lo be the first reported case of thyroid hemiagenesis in Malaysia and this congenital anomaly is discussed with a brief review of the literature.