THYROID HEMIAGENESIS

Background and Objectives: Thyroid hemiagenesis is a rare embryologica l condition, predominantly in females (3:1) with a left lobe being abs ent. The associated diseases in the remaining thyroid lobe include ben ign 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 wi th hemiagenesis is quite rare and very few cases are reported in the w orld 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 c arcinoma. The patient underwent thyroid exploration and left thyroid l obectomy. Results: The operative findings confirmed hemiagenesis of th e right lobe and papillary carcinoma in the left lobe. All four parath yroids were in normal position. Conclusions: The purpose of this prese ntation is to discuss and review the literature on thyroid hemiagenesi s and present a rare case of absent right thyroid lobe with carcinoma in the remaining left thyroid lobe. (C) 1997 Wiley-Liss, Inc.