Thymic cysts are rare, and those occurring totally within the mediastinum are even more unusual. A review of the literature by Krech et al in 1954 found only eight cases to which he added four cases of his own.1 Subsequent reviews by Podolsky et al,2 Zanca et al,3 Seltzer et al,4 and Barrick and O'Kell5 emphasized the paucity and the variety of symptoms caused by mediastinal thymic cysts. Only one patient reported dysphagia. Review of 1,000 mediastinal tumors and cysts by Oldham6 in 1971 failed to add any additional cases. Pokorney7 reported three cysts in 109 patients under 16 years of age with mediastinal masses and Whittaker8 found two cases in 105 pediatric patients with mediastinal tumors.
Report of a Case.—A 4-year-old boy was admitted to the Boston Floating Hospital because of dysphagia of ten days' duration. Chronic granulomatous disease had