Right thyroid hemiagenesis presenting with a contralateral simple diffuse goiter: case report.

Thyroid hemiagenesis (THA) is a rare congenital disorder in which one thyroid lobe fails to develop. A variety of pathological conditions can occur in the remaining thyroid tissue in association with this rare anomaly such as subacute thyroiditis, colloid nodules, Graves' disease, simple goiter, Hashimoto thyroiditis, adenoma and thyroid carcinoma. The association of thyroid hemiagenesis with simple diffuse goiter is rare, and very few cases have been reported in the literature. A 30-year-old female patient presented at the thyroid clinic because of anterior neck swelling for approximately 2 years, thus raising the suspicion of a thyroid disorder. Physical examination revealed an approximately 5 × 5 cm anterior neck mass consistent with a goiter. The thyroid function test results were within normal limits. Ultrasonography of the anterior neck (thyroid gland) revealed thyroid hemiagenesis of the right lobe and a contralateral (left) diffusely enlarged thyroid gland, which had areas of tiny cystic components with a spongy appearance. Fine needle aspiration cytology demonstrated that the lesion was a colloid goiter and the patient was on regular follow up with thyroid function tests and ultrasound as the patient was without symptoms. Finally, the diagnosis of right thyroid hemiagenesis with a contralateral simple diffuse goiter was made which was a very rare association. Right sided thyroid hemiagenesis was also a very rare finding compared to left sided.