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Introduction: Observation of schistocytes on the peripheral blood following haematopoietic stem cell transplantation (SCT) is a common finding. As their presence is not specific to the onset of SCT-related thrombotic microangiopathy, we evaluated the interest of schistocyte measurement twice a week during the entire follow-up of 195 patients undergoing SCT, particularly focussing on the 125 allogeneic SCT., Methods: Schistocytes were strickly defined as triangular-, crescent- or helmet-shaped red blood cells according to consensus standards and were checked blindly under the microscope and with computer image analysis., Results: Mean schistocyte percentage was 0.7% (±0.5%, reference value ≤0.5). High schistocyte percentage was observed after allografts (0.79%) when compared to autologous SCT (0.47, P < 0.001). All but one patients undergoing allogenic SCT had schistocytes ≥0.6%. Conversely, significant schistocytosis was observed in 20% of the autologous SCT. Initial diagnosis [chronic myelocytic leukaemia, acute lymphoblastic leukaemia (ALL)], high-risk status, unrelated transplant and conditioning regimen including total body irradiation influenced higher schistocyte percentage (≈0.9%). Significant rise in the schistocyte percentage was observed during acute/chronic graft-versus-host disease, veno-occlusive disease (VOD), cholestatic hepatitis, haemorrhagic cystitis (HC) and pulmonary complications. Multivariate analysis showed a significant association between thrombotic microangiopathy (TM), renal impairment and delayed thrombopaenia after day 50, and schistocyte >1.2%. SCT-TM grade ≥2 occurred in nine patients. A marked rise in schistocyte >4.5% was observed, which was not reached during the other SCT-related complications. Children with ALL, undergoing unrelated allogeneic SCT, with early acute graft-versus-host disease refractory to steroids were prone to present SCT-TM, associated with VOD, interstitial pneumopathy and HC, resulting in a high mortality rate (six of seven patients). Our data confirmed that schistocytosis was common after SCT. Mild percentages were likely concomitant with extensive endothelial damage but higher percentage should have prompted to a close monitoring with SCT-TM investigation., Conclusion: In our experience, systematic schistocyte count after HSCT proved to be useful: the occurrence of an increased percentage was a surrogate marker for complications even if unspecific for TM., (© 2011 Blackwell Publishing Ltd.)

We report on a male patient affected by Shwachman Diamond syndrome (SDS) who presented an unusual delayed neutropenia and then developed a poorly differentiated acute myeloid leukaemia (M0-AML) with trilineage myelodysplasia in adulthood. Conventional cytogenetics revealed complex karyotypic changes (monosomies 20, 21, 22, additional 15p). The patient was treated with conventional chemotherapy but never reached complete remission of leukaemia and died 18 months after diagnosis. SDS is an inherited bone marrow failure syndrome with a high propensity to leukaemic transformation. Since neutropenia may be intermittent or with delayed onset, and leukaemic transformation may not occur until adulthood, full blood count should be regularly monitored in such patients.