We report a case of an eight year old female child with a midline neck mass for seven years. Since its early presentation, this midline mass has recently increased in size. A presumptive diagnosis of thyroglossal duct cyst was made clinically and planned for surgery. Preoperative evaluation revealed hypothyroidism, hence she was referred to us for the management of the same prior to excision. On further evaluation 99 Tc-thyroid scan showed that this midline mass was in fact the only functioning thyroid tissue and ultrasonography revealed no thyroid tissue in usual location, therefore no surgery was performed. This case demonstrates the essential role of a thyroid scan and ultrasonography in the preoperative evaluation of a midline neck mass.