[Thymoma in childhood. Clinical case].

Thymoma, the most common tumor mediastinum, is a neoplasm arising from the epithelial cells of thymus. Nearly all thymomas present in adult life. Thymomas in children are exceptional. Chest X-ray, CT, magnetic resonance and fine-needle aspiration help for diagnosis. Surgical resection represents the treatment of choice and the outcome of surgery has been shown to depend on the local invasiveness of the tumor.