Paroxysmal cold hemoglobinuria

This a rare autoimmune hemolytic anemia that is due to cold reacting IgG antibodies to the RBC P antigen. These antibodies bind RBCs at cold temperature and with elevated temperature the bound red cells undergo a complement induced destruction (hemolysis). These biphasic unusual cold reacting IgGs are also known as Donath-Landsteiner antibodies. These patients may undergo hemolysis when exposed to cold temperature and present with hemoglobinuria. Peripheral blood may show some neutrophils with erythrophagocytosis.