Long-Term Clinical Outcome of Children with Acquired Aplastic Anemia in Brazil.
Authors: Pereira Garanito Marlene , Filho Vicente Odone , dos Santos Marcela Vieira , Velloso Elvira , Dulley Frederico L. , Carneiro Jorge David Aivazoglou 
Published: October 2019

Abstract
Abstract 4216

Introdution/ Backgound
Acquired Aplastic Anemia (AAA) is a rare hematologic disorder characterized by pancytopenia and hypocelular bone marrow. The pathophysiology is immune mediated in most cases. Environmental exposures to drugs, viruses and toxins, are thought to trigger the aberrant immune response in some patients. However, 50 to 74 percent of cases are classified as idiopathic. The highest frequency occurs in young population (15 to 25 years) with a second peak at age of 65 to 69 years. Immunosuppressive therapy is the best treatment in children with AAA who do not have a suitable donor for allogeneic stem cell transplantation.

Materials and methods
We reviewed the medical records of patients diagnosed with severe (SAA) and very severe acquired aplastic anemia (vSAA) at the Department of Pediatrics, Instituto da Criança – Hospital das Clínicas, University of Sào Paulo, Brazil from December, 1992 to December, 2007. We analyzed the clinical characteristics of the patients at diagnosis and the response to immunosuppressive therapy (IST) and hematopoietic stem cell transplantation (HSCT).

Results
In this study, 47 patients (27 boys and 20 girls), younger than 16 years, were diagnosed with vSAA (n= 21) or SAA (n=26). The median age was 7,71 years, ranging from 0.5 to 16 years and the average time history (beginning of signs and symptoms related to the disease and diagnosis) of the disease was 4,82 months, ranging from 0,25 to 48 months. Of the 47 patients, 45 had idiopathic AAA and 2 had hepatitis-associated. The median follow-up was 6,91 years for the patients treated with IST and 3,10 years for the patients who underwent to HSCT.
One patient died before any treatment. For the eight patients who underwent to allogenic HLA-matched HSCT the 5-years-survival probability was 50%.
For the 38 patients treated with IST, ten of them received cyclosporine and a short course of corticosteroids (CsA/CE) and 28 received antithymocyte globulin plus cyclosporine (ATG/CSA). The 5 years survival probability was 40% and 55%, respectively (p:0,0054). According to the severity of AAA, we did not show a significant difference in survival (p:0,32). Eight patients received second treatment after 1 year and 6 months (6 ATG from different species and CsA, 1 CsA and 1 thalidomide) and the probably of survival at 5 years was 60%. Among the 18 patients who responded to IST, four relapsed (22%). Two patients developed acute myeloid leukemia at 5 and 12 years after diagnosis.

Conclusion
Our results both for patients undergoing HSCT, as well as patients undergoing IST are lower in comparison to other hematological centers. Probably, this discrepancy is related to the prolonged time of disease when patients are admitted to our service. Unfortunately, the difficulty of access to specialized centers for diagnosis and early treatment in our country is a reality and this fact contributes to the delay to the beginning of treatment.

Disclosures:
No relevant conflicts of interest to declare.