Screening for paroxysmal nocturnal hemoglobinuria (PNH) clone in Egyptian children with aplastic anemia.

Aplastic anemia and paroxysmal nocturnal hemoglobinuria (PNH) are clinically related. In addition to their concurrent or sequential appearance in individual patients, PNH and aplastic anemia share several pathophysiologic features. The aim of the present study was to screen for PNH clone in Egyptian aplastic anemia pediatric patients before the initiation of any specific therapy and to evaluate the clinical status of studied patients 3-6 months after initiation of immunosuppressive therapy. We studied 11 pediatric patients with newly diagnosed acquired aplastic anemia and followed them up clinically for 3-6 months after initiation of immunosuppressive therapy. In addition to routine clinical and laboratory evaluation, sucrose lysis test and staining of bone marrow for CD59 were performed in all subjects. All studies cases had severe aplastic anemia (SAA) except one case which had very severe aplastic anemia (VSAA). Sucrose lysis test was negative in all studied cases. Presence of PNH clone (as evident by loss of normal staining of hematopoietic cells for CD59 = CD59 negative cells) was evident in four subjects. All cases with PNH clone were >6 years old and one of them developed splenic vein thrombosis. As regards the laboratory data WBC < or = 2.8 x 10(3)/mm3 and reticulocytes > or = 0.6 per cent were the most frequent factors associated with PNH clone found in all PNH subjects, but only in 28.6 per cent and 14.3 per cent respectively, of non-PNH subjects. Mortality rate was higher in non-PNH subjects (28.5 per cent) compared to 25 per cent of PNH subjects. We conclude that immunohistochemical staining of bone marrow sections is a sensitive tool to detect the emergence of PNH clone in aplastic anemia patients. Thrombotic complications should be anticipated in cases with aplastic anemia having a PNH clone.