RESUMEN
Juvenile differentiated carcinoma thyroid is a rare entity. It differs from adult differentiated thyroid carcinoma in a variety of ways, including large tumor volume at presentation with early involvement of the capsule, more frequent nodal and distant metastases, greater expression of sodium-iodide symporter and early recurrence. The overall survival seems to be better than for adult patients; however, due to high and early recurrence rates, prompt and adequate treatment is advocated. The mainstay of treatment includes total thyroidectomy, central lymphadenectomy with modified radical lateral lymphadenectomy, followed by ablation with radioactive iodine (RAI). Both modalities improve the final outcome, but RAI ablation decreases cause-specific death risk independent of the extent of surgery. We present the case of a 5-year-old girl, the youngest ever treated in our country with surgery and RAI therapy successfully after being diagnosed as papillary carcinoma of the thyroid, follicular variant.