It is rare to have myelodysplastic syndrome(MDS) and paroxysmal noctunral hemoglobnuria(PNH) coexist as two full blown disorders but PNH cells can be present in MDS and PNH can resemble some features of MDS. Among acquired stem cell disorders, auch as myelodysplastic syndromes (MDS) and aplastic anaemia (AA), links between paroxysmal nocturnal haemoglobinuria (PNH) and AA, have been often described, whereas the relationship between MDS and PNH is not entirely clear. Many reports identified small PNH clone in both aplastic anemia or low-risk myelodysplastic syndrome and hemolysis(breaking of red cells), which is a feature on PNH, is present to some degree (< 10%) in these conditions but that hemolysis does not contribute significantly to the underlying anemia. Using high-sensitivity flow cytometry, approximately 60% of patients with aplastic anemia and 20% of patients with low-risk MDS have been found to have a detectable population of PNH white and red cells. In these cases, the focus of treatment is on the Bone Marrow failure component of the disease, aplastic anemia or MDS. Hemolysis inside vessels is the dominant feature of classic PNH, and this process is blocked by the complement inhibitor eculizumab(Soliris). When hemolysis is the predominant feature, treatment should be directed to the PNH component. The large majority of patients with PNH/AA and PNH/MDS have relatively small PNH clones (< 10%) and require no specific PNH therapy; in these cases, treatment should focus on the underlying BM failure syndrome.
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Iwanaga M, Furukawa K, Amenomori T, Mori