Papillary Thyroid Carcinoma in a Pediatric Patient With Graves' Disease: A Case Report and Literature Review

Graves' disease (GD) is the most common cause of hyperthyroidism in children and adolescents; however, its coexistence with differentiated thyroid carcinoma is rare and may pose significant diagnostic challenges, as diffuse hyperplasia and hypervascularity can obscure malignant nodules. We report the case of a 15-year-old girl with GD treated with methimazole who was found on follow-up ultrasonography to have a hypoechoic thyroid nodule with punctate calcifications and peripheral vascularity. Although she was biochemically euthyroid, fine-needle aspiration cytology was consistent with papillary thyroid carcinoma (Bethesda V), and cervical lymph node mapping showed no evidence of metastatic disease. The patient underwent total thyroidectomy without complications and was discharged on the second postoperative day without the need for calcium supplementation. Histopathological examination confirmed an 11-mm papillary thyroid carcinoma, classic variant, arising in a background of GD, without capsular or vascular invasion. At nine months of follow-up, she remained clinically stable and biochemically euthyroid on levothyroxine, with no evidence of recurrence. This case highlights the importance of careful ultrasonographic surveillance and timely cytological evaluation of thyroid nodules in pediatric patients with GD and supports total thyroidectomy as a safe and definitive treatment when malignancy is suspected.