摘要:Adamantinoma is a rare, low grade, primary bone malignant tumor. Its rate of appearance on pediatric ages is minimal; therefore it could be misdiagnosed with several tumoral entities typical of childhood and puberty. We report the case of a 12-year-old teenager who coursed with increase of volume in the calf accompanied by intermittent pain, which was managed as osteosarcoma. After immunostaining tests were performed, the diagnostic of adamantinoma was established, leading to its surgical resolution and positive clinical outcome.