[Two cases of thymic cysts and review of the 220 Japanese cases].

Thymic cyst is relatively rare disease among mediastinal tumors. We reported two cases of surgical resected thymic cysts. Case 1: A 72-year-old female was found to have an abnormal shadow at right cardio-phrenic angle on chest X-ray film. Operative and pathological diagnosis was thymic cyst. Immunohistochemical study showed the epithelial cells lining the cyst to contain keratin and CEA but not CA19-9. Case 2: A 67-year-old male was pointed out to have an abnormal shadow at left mediastinum on a chest X-ray film during his stay in our hospital for acute myocardial infarction. Preoperative diagnosis was made to be a thymic cyst and operation was done. Pathological diagnosis was the same. Behçet's disease was accompanied in this patient. It is very rare to be complicated with thymic cyst. We reviewed 220 operated cases of thymic cyst in the Japanese literature.