Case of a child with paroxysmal nocturnal hemoglobinuria diagnosed by flow cytometry

A case of a child with paroxysmal nocturnal hemoglobinuria (PNH) is characterized by an increased sensitivity of the erythrocyte to hemolytic action of complement. The widely used Ham test may not always be reliable. Recently, a panel of monoclonal antibodies has become available to detect various glycosylphosphatidylinositol (GPI)-linked proteins by flow cytometry (FCM) and the deficiency of GPI-anchored proteins on the various kinds of cell membranes is implicated as the pathogenesis of PNH. We diagnosed a case of a child with PNH by FCM and complement lysis sensitivity (CLS) test, which showed the increased sensitivity of PNH erythrocytes to complement. His diagnosis was delayed because of Ham test negativity and rarity of PNH cases in children.