[Eight cases of thymic cyst]

Eight cases of thymic cyst were treated in our hospital from Jan. 1967 to Oct. 1989, which were 5.6% of all mediastinal tumors and 35% of congenital cysts. All cases were discovered incidentally by routine chest roentgenograms. All but one had no respiratory symptoms. There were no associated autoimmunological disorders such as myasthenia gravis. These tumors showed water density in computed tomography, low intensity area in T1 and high intensity area in T2 weighted magnetic resonance image. Garium scans were negative in all cases. Operations were performed in all cases for their diagnosis and treatment. All of our cases had no signs of malignancy on pathological examinations, and they are free of recurrence during subsequent follow ups. Study of intracystic fluid revealed high titer of CA19-9 and CEA in spite of normal titer in serum, which might be useful clue to preoperative diagnosis. For the poor risk patients with thymic cyst, percutaneous aspiration might be diagnostic and therapeutic when there is no sign of malignancy.