Thymic carcinoma which developed in a thymic cyst

Thymic carcinoma was found in a thymic cyst in a 60-year-old woman who was admitted to our hospital due to cough and pain in her right chest. Chest X-ray showed a huge shadow in the right mediastinum. Chest CT scan showed a cystic tumor with a solid mass. An operation revealed a solid tumor in the thymic cyst. Pathologic diagnosis was squamous cell carcinoma, that contained some glandular tissues. The patient has been in a good condition for two years after the operation. Although the concurrent occurrence of thymic carcinoma and thymic cyst is very rare, it should be added to the differential diagnosis when anterior mediastinal cystic tumor is associated with a solid mass lesion.(Internal Medicine 35: 215-218, 1996)