BACKGROUND AND OBJECTIVES: Thyroid hemiagenesis is a rare embryological condition, predominantly in females (3:1) with a left lobe being absent. The associated diseases in the remaining thyroid lobe include benign adenoma, multinodular goiter, hyperthyroidism, chronic thyroiditis, and rarely carcinoma. The most common pathology involved in thyroid hemiagenesis is hyperthyroidism. Presence of carcinoma in a patient with hemiagenesis is quite rare and very few cases are reported in the world literature. METHODS: We report a 30-year-old female who presented with left thyroid mass gradually increasing in size over a period of 3 months. The patient's pre-operative workup included a thyroid scan, which revealed a cold nodule in the left lobe with absent right lobe. A fine-needle aspiration biopsy was suspicious for papillary thyroid carcinoma. The patient underwent thyroid exploration and left thyroid lobectomy. RESULTS: The operative findings confirmed hemiagenesis of the right lobe and papillary carcinoma in the left lobe. All four parathyroids were in normal position. CONCLUSIONS: The purpose of this presentation is to discuss and review the literature on thyroid hemiagenesis and present a rare case of absent right thyroid lobe with carcinoma in the remaining left thyroid lobe.
