Abstract
Hemiagenesis of the thyroid gland is a rare congenital abnormality usually left unnoticed without associated thyroid disorders. The most common congenital anomaly of the thyroid gland is a thyroglossal cyst, followed by ectopic thyroid tissue and thyroid dysgenesis, which may be agenesis or hemiagenesis. Preoperative underevaluation of the thyroid hemiagenesis (THA) associated with other thyroid disorders may cause intraoperative difficulty in identifying the gland and difficulty in preservation or even identification of major neurovascular structures during neck exploration. We report a patient who presented to us with right-sided neck swelling. On further evaluation and neck exploration, the patient was diagnosed with THA of the left lobe with right colloid goitre.