Second Allogeneic Stem Cell Transplantation in a Patient with Hypoplastic Myelodysplastic Syndrome following a Primary Diagnosis of Aplastic Anaemia

out a human leucocyte antigen (HLA)-identical family donor. In case of allogeneic HSCT, conditioning strategies are different for both diseases, with the intensity usually being increased in MDS patients [5] . Owing to the above-mentioned difficulties in differentiating between hMDS and AA, some patients who were offered treatment and allogeneic HSCT for a diagnosis of AA later turned out to have had hMDS [1] . A 47-year-old male patient presented in the outpatient setting with persistent severe thrombocytopenia (platelets ! 5 ! 10 9 /l) and petechiae in June 2008. Initially, autoimmune idiopathic thrombocytopenia was suspected, but treatment with steroids and cyclosporin A (June to December 2008) was not successful. Bone marrow cytomorphology showed normoto hypocellular bone marrow fragments with severely reduced megakaryopoiesis. There was no dysplasia and no blast increase. Histopathology (Prof. Kreipe, Institute of Pathology, University of Hannover, Hannover, Germany) demonstrated a hypocellular bone marrow, aplasia of megakaryopoiesis and a reduction in erythroand granulopoiesis, but no increase in CD34+ cells. Multiparameter flow cytometry (MFC) excluded paroxysmal nocturnal haemoglobinDue to the morphologic and clinical overlaps, hypoplastic myelodysplastic syndrome (hMDS) can mimic aplastic anaemia (AA) [1] . Inadequate marrow material may be obtained because of severe hypocellularity. The frequency of hMDS in all MDS varies from 8 to 29% in most reports [2] . Most studies defined hMDS by marrow cellularity ! 30% related to age-adjusted healthy controls [2] . One option for differentiation is cytogenetics, but chromosomal aberrations are present in 6 50% of MDS patients [1] . AA can transform to MDS and secondary acute myeloid leukaemia, eventually being accompanied by clonal cytogenetic evolution. The correct differentiation between the 2 disorders is highly important as standard treatment approaches are different. Options for MDS start from supportive therapy to specific agents (e.g. 5-azacitidine). Patients with advanced MDS sometimes receive acute myeloid leukaemia-type induction chemotherapy or are offered allogeneic haematopoietic stem cell transplantation (HSCT) [3] . Immunosuppressive therapy with antithymocyte globulin (ATG) and cyclosporin A is only rarely used for specific subgroups of MDS patients [4] , but is the firstline strategy for patients with AA aged 1 40 years or withReceived: September 2, 2010 Accepted after revision: November 8, 2010 Published online: December 30, 2010