Thymoma accompanied by lichen planus.

Thymomas are associated at a high frequency with paraneoplastic autoimmune diseases. We treated a 64-year-old male with a thymoma, who also had lichen planus. The tumor was resected and diagnosed as thymoma, however, the symptoms associated with lichen planus did not subside and persisted. A preoperative examination showed an elevated serum level of squamous cell carcinoma antigen, which gradually decreased to normal after surgery. The findings of this case are interesting for understanding the correlation between a thymoma and autoimmune abnormalities.