Small cell lung cancer accompanied by lactic acidosis and syndrome of inappropriate secretion of antidiuretic hormone.

Lactic acidosis is a rare complication in lung cancer. We report a case of lung cancer accompanied by both syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and lactic acidosis. A 70-year-old man was referred to our hospital for examination of a left hilar mass shadow on a chest X-ray film. Small cell lung cancer (SCLC) was demonstrated by brushing the bronchial mucosa of the left lower lobe bronchus. His laboratory data showed SIADH and lactic acidosis that were probably due to SCLC. Fluid restriction improved SIADH, and combination chemotherapy for SCLC improved the lactic acidosis although the tumor size did not change.