Acquired RBC membrane defects – paroxysmal nocturnal hemoglobinuria

• Rare and acquired

• Unknown etiology; comes from a somatic mutation of affecting a pluripotent stem cell

• RBCs, granulocytes, and platelets are very sensitive to complement-mediated lysis due to a lack of 3 normal membrane proteins: decay accelerating factor (CD55), membrane inhibitor of reactive lysis (CD59) and a C8-binding protein; hemolysis may worsen at night

• Chronic hemosiderinuria may lead to iron deficiency

• Nonlytic complement interactions with granulocyte and platelet membranes predispose to infections and thrombosis (especially in the hepatic, portal, and cerebral veins)

• There is an increased risk for aplastic anemia and acute leukemia because this is a stem cell d/o

• Diagnosis can be suggested by a (+) sucrose hemolysis test and confirmed by performing an acidified serum test (Ham’s test) – flow cytometry of WBC and RBC levels of CD55 and CD59 is currently the gold standard

• Median survival is 10 years

Category: Medical Subject Notes , Pathology Notes