[A case of the cancer of an unknown primary site with elevated titer of serum CEA which was followed by the right sleeve upper lobectomy and mediastinal lymph node dissection].

A 63-year-old man was admitted because of right pneumothorax. As serum CEA revealed high titer, we underwent further evaluation, but we were not unable to find any lesion except mediastinal and hilar lymph node swelling. Though we performed sleeve resection of right upper lobe and mediastinal lymph node dissection, we were not unable to find primary lesion. But serum CEA was reduced markedly after surgery and we are not able to find the apparent primary site after that.