Severe immune hemolytic anemia due to pemetrexed in a patient with non-small cell lung cancer

Pemetrexed-induced immune hemolytic anemia is a rare acute complication and a potentially life-threatening syndrome. Here we report a case of severe hemolytic anemia induced by pemetrexed in a 67-year-old man with lung adenocarcinoma. Hemoglobin concentration reached a nadir of 6.8 g/dl after 6 days of pemetrexed initiation. Pemetrexed was discontinued and the patient was given a transfusion of red blood cells. The direct antiglobulin test was positive (anti-IgG = 4+, anti-C3d = 2+). The patient's plasma reacted with pemetrexed-treated red blood cells by the immune complex test.