Abstract: Thyroid hemiagenesis is a rare condition in which one entire thyroid lobe fails to develop. With only 270 cases reported worldwide1,this may be the first Australian example of this disorder described in the literature. We report upon the case of a 56 year old woman referred by her GP for specialist assessment. Her primary complaint was a self – palpated painless neck mass with associated subjective dysphagia and tiredness . Her concomitant history also included perimenopausal symptoms and history of neck injury from a childhood motor vehicle accident.
Despite clinically presenting in a euthyroid state the patient described further symptoms of altered voice,weight gain, constipation and dry skin. Her thyroid antibodies were negative, with TFTs showing TSH 6.56, FT4 15. Ultrasound imaging revealed an atrophic right thyroid lobe with an enlarged left lobe with associated benign colloid cysts.
There is uncertainty surrounding the prevalence of thyroid hemiagenesis2 with many patients remaining undiagnosed until development of clinical symptoms. Many patients do not display compensatory lobe size which may suggest defective lobule development1.