Invasive thymoma associated with lung cancer: report of a case.

We report herein a case of invasive thymoma simultaneously associated with lung cancer. A 64-year-old man presented with a cough and anterior chest pain, and preoperative examinations revealed an anterior mediastinal tumor as well as lung cancer. The patient underwent a total thymectomy, partial resection of the right lung, left lower lobectomy, and mediastinal lymph node dissection, followed by radiotherapy. Although it is well known that thymomas may be accompanied by nonthymic cancers, invasive thymomas occurring coincidentally with lung cancer are rarely reported in Japan. This case is very interesting in its relation to the oncogenesis of thymomas.