[Resected case of thymic cyst with primary lung cancer]

Thymic cyst is a rare and benign tumor of mediastinal tumor. A 77-year-old male was pointed out the tumor shadow on Chest X-ray film and diagnosed lung cancer. On admission some examination was performed and revealed mediastinal tumor accidentally. Primary lung cancer was completely resected and mediastinal tumor was extirpated. Pathological examination revealed lung cancer (poorly differentiated squamous cell carcinoma) and thymic cyst. Many methods of examination were tried for diagnosis of thymic cyst, but couldn't diagnose exactly before its resection. Some of the patients with thymic cyst was reported to develop SVC syndrome or change to malignant tumor. Therefore we think complete resection is the best treatment.