[Accessory thymus in cervical ectopy: apropos of a case].

: Cervical tumors of thymic origin are considered to be uncommon lesions in the differential diagnosis of neck masses. They can be either cystic or solid. The authors present one case of solid cervical thymic tumor in a 2 month-old baby. The embryogenesis of the thymus explains the cervical location of these tumors. Theories of physiopathology are presented. The clinical presentation is variable and their nature is often recognized only upon surgery and preoperative pathologic examination. Some cases of thymoma and respiratory complications resulting from ectopic thymus have been described in the literature, so that total excision of the mass must be performed. This lesion may be more common than suggested in the literature.