The aberrant cervical thymus. Embryology, Pathology, and clinical implications.

Cervical thymic anomalies are not as rare as previously suggested. Six cases were encountered over a relatively short period of time, prompting us to report them and emphasize the importance of this entity. Five of the six patients were children, two of them infants less than one year old. The occurrence of thymic remnants in the neck of young children is not surprising, considering the nature and behavior of the thymus at different stages of life. After a brief embryologic survey, the various types of cervical thymus (solitary ectopic, cystic, or partially arrested descent) and their pathogenesis are discussed. The rare occurrence of thyroid and parathyroid tissue within the mass of a large cervical thymic cyst is reported and evaluated. Cervical thymic lesions can either be symptomless or cause severe dyspnea and dysphagia, especially in the young infant. Accurate diagnosis and an intelligent surgical approach in the child with a cervical mass can avoid the obvious parental apprehension and lead to the correct treatment. Symptoms due to pressure on neighoring structures are promptly eliminated after excision, and prognosis is excellent.