PNH is an acquired disorder of hemopoiesis and is characterized by recurrent episodes of intravascular hemolysis due to an increased sensitivity to complement-mediated hemolysis . A crucial pathophysiological mechanism is an acquired defect of the glycosylphosphatidylinositol-anchored proteins, namely CD55 and CD59 .
Flow cytometry analysis of red blood cells with monoclonal antibodies directed against CD55 and CD59 is now the gold standard technique for the diagnosis of PNH . The normal values of CD55 and CD59 are more than 85.4% and more than 99.8%, respectively. In the present case, the values of CD55 and CD59 were 18% and 78.6%, respectively. Consequently, PNH was diagnosed.
PNH presents three clinical manifestations: (a) an acquired intravascular hemolytic anemia due to the increased susceptibility of the erythrocyte membrane to complement-mediated lysis; (b) thrombosis in large vessels, such as hepatic, abdominal, cerebral, and subdermal veins; and (c) mild to severe bone marrow hypoplasia that results in different degrees of pancytopenia. The triad of hemolytic anemia, thrombosis, and pancytopenia makes PNH a truly unusual clinical syndrome . These manifestations were visible in our case.
Deficient expression of CD55 and CD59 has recently been reported in patients with autoimmune hemolytic anemia, autoimmune thrombocytopenia, or SLE [6, 7]. An autoimmune condition such as SLE may contribute to the pathogenesis of PNH . It is a very interesting phenomenon and might be associated with the pathogenesis of our present case.