Endocrine Abstracts

Introduction: Thyroid nodules are less common in children than adults, however they have an increased risk of being malignant compared to adults. Follicular adenomas are the most common benign thyroid lesion in children. They present twice as frequently in girls, and the average age at presentation is 12.5 years. Case reports predominantly document cold benign nodules in children. We present the case of a solitary thyroid nodule due to hyperfunctioning follicular adenoma in a 13-year-old girl.

Case: A 13-year-old girl was referred with an incidental finding of a left-sided thyroid swelling. There were no symptoms of thyroid dysfunction. She had no significant past medical history or family history of thyroid disorders or malignancy. On review, she was clinically euthyroid, however she had a smooth, firm, non-tender, solitary, left-sided thyroid mass measuring 5x4 cm which was mobile on swallowing. No lymphadenopathy was evident. Biochemical assessment showed evidence of mild hyperthyroidism with a suppressed TSH 0.02 mIU/l(0.5-4.88), raised FT3 9.6 pmol/l(3.9-7.70) and a normal FT4 14.6 pmol/l(11.2-21.3). Thyroid peroxidase (TPO) antibodies and TSH receptor antibodies (TRAB) were negative. An ultrasound scan revealed a large nodule filling the entire left lobe of her thyroid, with a volume of 26ml. It contained cystic spaces separated by soft septae and peripheral solid components. The right lobe appeared normal. Pertechnetate thyroid scan showed heterogenous and intense uptake of iodine-123 within the left lobe of thyroid with faint homogenous uptake in the right lobe suggestive of a hyperfunctioning left-sided thyroid nodule. The patient underwent a left hemithyroidectomy. Histology found a cystic nodule measuring 50mm suggestive of a follicular adenoma, with complete excision. The surrounding thyroid tissue was unremarkable. Post operatively, she had transient clinical and biochemical hypothyroidism which resolved without treatment over 2 months.

Conclusion: Autonomously functioning hot nodules in children are rare. Although often benign, they can, on occasion, be malignant. It is not always possible to make this differentiation on ultrasound. Surgical management can definitively treat thyroid dysfunction in these cases and avoid the need for long-term medication whilst also allowing a definitive histological diagnosis to be made.