Thymic squamous cell carcinoma lurking in a growing large cyst A case report

An 81-year-old man was admitted for resection of an asymptomatic left anterior mediastinal tumor. Chest computed tomography showed that a small, homogeneous lesion had grown to a large, cystic lesion (80 mm) over a 5-year period. The cystic tumor was removed with adherent structures such as the left upper pulmonary parenchyma and lower part of the left innominate vein via median sternotomy with assistance from a left thoracoscopic procedure. Macroscopically, a solid tumor was located within the large multilocular cyst. The pathological diagnosis was cystic squamous cell carcinoma (12 mm), which had not infiltrated any surrounding organs. The patient has remained well without recurrence as of 4 years postoperatively.