Thymic squamous cell carcinoma.

In the case described, a 43-year-old man had an asymptomatic mass involving the right hilar and superior mediastinum. At surgery, the tumor was found to have invaded the right middle lobe of the lung and the pericardium. The mass was found to be a thymic squamous cell carcinoma, a rare tumor. Two serum tumor markers--lipid-associated sialic acid and squamous cell carcinoma antigen--were elevated. The patient underwent postoperative radiation therapy and has responded favorably to treatment. He had no clinical evidence of metastasis or recurrence as of 43 months postoperatively.