[THYROID HEMIAGENESIS: A CASE REPORT].

INTRODUCTION: Thyroid hemiagenesis is a rare congenital anomaly characterized by the absence of one thyroid lobe and the isthmus. This case report presents a 4-year-old girl with a history of prematurity. Incidentally, during a routine ultrasound evaluation of the neck, thyroid hemiagenesis was detected along with the presence of normal lymph nodes. The right thyroid lobe was absent, while the left thyroid lobe was preserved. No previous neck or thyroid surgeries were reported.

DISCUSSION: This provides an overview of thyroid hemiagenesis, including its prevalence, predominant involvement of the left lobe, possible genetic and environmental factors, and associations with thyroid and extrathyroidal pathologies. Imaging modalities, such as ultrasound and scintigraphy, play a crucial role in diagnosing thyroid hemiagenesis and identifying additional thyroid gland abnormalities. Long-term follow-up and careful monitoring are recommended to assess thyroid function and identify potential structural abnormalities. The optimal therapeutic approach for thyroid hemiagenesis remains controversial, and further studies are needed to determine the clinical significance and long-term outcomes of this rare condition.