A Case of Methemoglobinemia Caused by Toluidine Revelation with Dyspnea and Cyanosis

Toluidine is a known cause of bladder cancer, but it is less widely recognized as a cause of methemoglobinemia because methemoglobinemia is rare. We herein report a case of methemoglobinemia caused by toluidine in a 50-year-old man. A solution of toluidine overflowed from its container during transportation and adhered to the man’s clothes, but he drove to his workplace 100 km away without changing his clothes or undergoing decontamination. Before arriving at his workplace, he developed dyspnea and called emergency services, and he was then transported to a local hospital. He had significant cyanosis upon arrival, and arterial blood gas analysis revealed a high methemoglobin level of 44%. He was diagnosed with toluidine-induced methemoglobinemia and was transported to our hospital, where he was admitted to the intensive care unit. Treatment for methemoglobinemia was started immediately after hospitalization, and the patient’s symptoms and methemoglobin level improved. Methemoglobinemia should be considered in workers who handle toluidine and develop cyanosis and dyspnea.