[Cervical ectopic thymus]. / Timo ectópico cervical.

We present a case of ectopic thymus in an eight month old male baby, with a right lateral tumor of the neck. Ectopic thymus is a pathology rarely observed, its embryogenesis could explain its cervical localization. X Ray, ultrasonography, IRM, esophagoscophy and laryngoscophy may be helpful in the differential diagnosis with other tumors of the neck. Due to the fact that cystic lesions and neoplasis developments take place, the chosen treatment is the complete chirurgical extirpation. But at the absence of symptoms, no treatments is advisable because eventually the thymus spontaneously involutionates.