Abstract
Recently an unusual mass presenting in the left neck of a 16-day-old boy was removed. The histology showed a thymic tissue. Previous cases reported in Japanese literatures were reviewed. Literatures revealed 11 infant cases and 18 adults in whom the thymus presented in the neck as a cervical mass. In infants, 8 cases demonstrated normal thymic tissues, 3 thymic cysts and one thymolipoma. In adults normal thymic tissue was observed in one, thymic cyst in 5, thymoma in 8 and malignant thymoma in 4. Ectopic thymic tissue of the neck in infants should be removed, because cystic degeneration or malignant change may occur in future. Unilateral thymic removal has little influence on patient's growth, but in cases with bilateral involvement only unilateral thymus should be removed in infants.
