Unusual underlying disorder for pulmonary embolism: Cold agglutinin disease.

Cold agglutinin disease (CAD) is a form of autoimmune hemolytic anemia caused by cold-reacting autoantibodies. The manifestations of CAD are commonly anemia, acrocyanosis, and fatigue caused by hemolysis and agglutination of red blood cells (RBCs) at a temperature lower than normal body temperature. We report a case of CAD presenting with pulmonary embolisms in an 86-year-old man. The patient visited our emergency department complaining of acute chest pain and respiratory distress. Laboratory data showed decreased RBC and hematocrit and markedly elevated mean corpuscular hemoglobin (MCH) and MCH concentration (MCHC). A contrast-enhanced computed tomographic scan demonstrated bilateral massive pulmonary embolisms. After admission, diagnosis of CAD was made on the basis of a high cold agglutinin titer without other factors of coagulation. CAD can contribute to the onset of pulmonary embolisms. It is necessary to incubate blood samples at 37 °C when laboratory data show markedly elevated MCH and MCHC and to consider the presence of cold agglutinins as an underlying disorder for the formation of venous thrombosis. <Learning objective: Cold agglutinin disease can contribute to the onset of pulmonary embolisms. It is necessary to incubate blood samples at 37 °C when laboratory data showed markedly elevated mean corpuscular hemoglobin (MCH) and MCH concentration (MCHC) and to consider the presence of cold agglutinins as an underlying disorder for the formation of venous thrombosis. Complete blood count including MCH and MCHC is always ordered, but we may have overlooked the meaning of abnormal results. We must be aware of these parameters and carefully examine the underlying mechanisms of thrombosis.>.