Abstract

Six cases of large thymic cyst are described; five were cystic thymomas and one was nonneoplastic. Two of the thymomas were not only grossly degenerate but showed severe chronic inflammatory change, so that the diagnosis might be missed. The classification of cysts into congenital, inflammatory, and neoplastic groups is discussed. Cystic teratomata of the thymus, lymphatic cysts, and bronchogenic cysts are classed separately since thymic location does not affect their natural history. Cystic thymomas are still not well known clinically, and the literature on the subject is reviewed. It is probable that quite a few non-specific cysts of the anterior mediastinum are of thymic origin.