Transplant-associated thrombotic microangiopathy in children with malign and non-malign diseases after allogeneic stem cell transplantation

Purpose: Transplant-associated thrombotic microangiopathy is a bothersome complication in terms of morbidity and mortality after allogeneic stem cell transplantation. It is believed that the endothelial injury causes to thrombotic microangiopathy, but the pathogenesis is not known completely. In 2007, Although diagnostic criteria can be obtained, there is no concurrence for the treatment particularly. Even though thrombotic microangiopathy is considered by transplantation physician recently, adequate prospective multi-center studies and broad serial cases are not presented yet. We aimed to report transplant-associated thrombotic microangiopathy insidence, mortality rates and risk factors prospectively between January 2006 and June 2008 in Çukurova and Hacettepe University pediatric stem cell transplantation units.Material and Methods: Fifty transplantation cases were included in our study. Patients? data were analysed retrospectively. Peripheral blood and bone marrow were used as a source of stem cell. The Diagnosis of transplant-associated thrombotic microangiopathy was done according to the reports of International Working Group in 2007.Results: Of these patients were 27 (54%) male and 23 (46%) female. Patients were aged between 3 months and 18 years (mean 8.54 ± 5.06). The patients with malign and non-malign disaeses were 13 (26%) and 37 (74%), respectively. Myeloablative and non-myeloablative conditioning regimens were used in 29 (58%) and 21 (%42 ) patients, respectively. Bone marrow in 32 (64%) and peripheral blood in 18 (36%) were applied as the stem cell sources. While 46 (92%) of patients were HLA full-matched, 4 (8%) were HLA mis-matched. 35 (70%) of donors were sibling and 15 (30%) of whom were parents and first degree relatives. There is not any unrelated donors. Transplant-associated thrombotic microangiopathy was seen in 3 of 50 cases (6%). The mean beginning time and mortality rate of thrombotic microangiopathy was on day 43 and 33,3 %, respectively. While thrombotic microangiopathy was recorded in 3 of 18 patients given peripheral blood, non of 32 patients given bone marrow thrombotic microangiopathy was seen. (p<0,05).Coclusion: In our study, peripheral blood is a risk factor for thrombotic microangiopathy as the source of stem cell (p<0.05). There was no relationship between thrombotic microangiopathy and risk factors such as gender of girl, non-myeloablative conditioning regimen, high dose busulphan, mis-matched HLA type, cyclosporin using, the presence of malign disease, infection and acute GVHD (p>0,05).