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Background: Autoimmune hemolytic anemia (AIHA) is a rare, life-threatening disease in pediatrics. This article describes the clinical features, diagnostic workup, treatment and outcome in patients with AIHA., Method: Medical charts of under 18-year-old patients with AIHA treated at a tertiary Brazilian institution from 2006 to 2021 were retrospectively reviewed. Data analysis was primarily descriptive, using medians, interquartile ranges, and categorical variables presented as absolute frequencies., Main Results: Twenty-four patients (14 female, 10 male) were evaluated in this study. The median age at diagnosis was 5.99 years (range: 0.25-17.1 years) and the median hemoglobin level was 4.85 g/dL (range: 4.17-5.57 g/dL). Most had warm antibodies (83.3 %). Twelve patients (50 %) had known underlining diseases, four (16.6 %) presented with AIHA concomitant with acute infectious diseases and three (12.5 %) had an undetermined post-vaccine association. Steroids and intravenous immunoglobulin were first-line therapy in 23 cases. Seven patients (29.1 %) required second and third-line treatments (rituximab, cyclophosphamide and splenectomy). The median follow-up period was 4.4 years (range: 1.0-6.7 years). Thirteen patients (54.1 %) were discharged, five cases (20.8 %) were lost to follow-up and no patient died. The median age for the six remaining patients was 11.53 years (8.5-14.7) with all of them having complete responses with no further therapies., Conclusion: Most cases of AIHA are secondary to an underlying systemic disease or have a possible correlation with infections/vaccines and respond to steroids. The second and third-line therapies for refractory and relapse cases remain a dilemma. A prospective, multicenter study is essential to address the best therapeutic combinations., Competing Interests: Conflicts of interest The authors declare no conflicts of interest, (Copyright © 2024 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. All rights reserved.)

Introduction: Although still rare, pulmonary embolism (PE) in children has been increasing over the years. Data regarding this group of patients are still sparse, which contributes to the lack of standardized prophylaxis protocols and the misdiagnosis. This study aimed to determine the incidence of pediatric PE at a Brazilian tertiary hospital, describe clinical characteristics and identify possible risk factors. We also analyzed the diagnosis and management of PE., Methods: This was a retrospective review of tertiary Brazilian single-center data of all pediatric patients (0 - 18 years) with acute PE, diagnosed radiologically, from September 2009 to May 2019., Results: The incidence of PE was 3.3 cases per 10,000 hospitalized children. All the twenty-three cases had some risk factor identified and sixteen of them (69.5%) had more than one risk factor. The most important were central venous catheter (39.1%), malignancy (34.8%) and recent surgery (34.8%). Among the children with identifiable symptoms (69.5%), the most common was dyspnea (56.2%). Only one patient did not receive antithrombotic therapy because of the high bleeding risk and most patients (70.6%) were treated for 3 to 6 months. Among the nineteen patients alive at the end of the six-month follow-up, ten (52.6%) repeated the PE image control. Seven of them (70.0%) had complete or partial resolution of the thrombosis and none had worsening images., Conclusion: Our lower incidence than that of the current literature may reflect underdiagnosis due to low suspicion of PE. At least one risk factor was identified in all patients, which emphasizes the importance of increasing awareness of high-risk children., Competing Interests: Conflicts of interest None., (Copyright © 2022 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. All rights reserved.)

Introduction: The Evans syndrome (ES) is a rare, often chronic, relapsing and treatment-refractory hematological disorder. We described the clinical features, diagnostic workup, treatment and outcome in patients with ES., Method: We performed a retrospective chart review of patients aged < 18 years with ES admitted to a tertiary center in Brazil from 2001 to 2021. The analysis of the data was primarily descriptive, using median, interquartile range and categorical variables presented in absolute frequencies., Main Results: Twenty patients (12 female, 8 male) were evaluated in this study. The median age at the initial cytopenia was 4.98 years (1.30-12.57). The ES was secondary in nine cases (45%), of which six patients (30%) showed autoimmune disease (AID) or primary immunodeficiencies (PID) and one presented a spontaneous recovery. Steroids and intravenous immunoglobulin were first-line therapy in 19 cases. Twelve patients (63%) required second-line treatments (rituximab, cyclosporine, splenectomy, sirolimus, cyclophosphamide, mycophenolate mofetil, azathioprine and eltrombopag). The median follow-up period was 2.41 years (1.4 -7.52). One patient (5%) died of underlying neuroblastoma, one case (5%) was lost to follow-up and four patients (20%) received a medical discharge. The median age for the 14 remaining cases was 12.6 years. Twelve patients (85.7%) were in complete response (CR) with no therapies. Two patients (14.3%) were in CR with chronic therapy., Conclusion: As ES may be a symptom of AID and PID, a thorough rheumatological, immunologic and genetic workup and a careful follow-up are essential. The second-line treatment remains a dilemma. Further prospective studies are needed to address the optimal therapeutic combinations, morbidity and mortality in this disorder., Competing Interests: Conflicts of interest No authors have any conflict of interest that is directly relevant to the content of this manuscript., (Copyright © 2022 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. All rights reserved.)

Objective: To evaluate the efficacy and safety of romiplostim (thrombopoietin-receptor agonist) in the treatment of pediatric immune thrombocytopenia (ITP)., Methods: Searches were conducted in MEDLINE, EMBASE, LILACS, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov (from January 2011 to August 2021). Randomized controlled trials (RCTs), double-blind, comparing romiplostim with a placebo in pediatric persistent or chronic ITP were included. The primary outcome was the overall response rate (platelets ≥ 50 × 10 9 /L) in the absence of rescue therapy for at least two consecutive weeks. The secondary endpoints were the minimization of clinically significant bleeding and the necessity for rescue treatments and the maximization of safety (incidence of overall adverse events) and durable response (maintaining platelet counts for at least twelve weeks)., Results: Two double-blind randomized placebo-controlled trials (84 participants) were included in this systematic review. Our data showed that, compared to the placebo group, the proportion of patients achieving durable platelet response was significantly higher in the romiplostim group (p = 0.003, RR = 6.34, 95%CI = 1.89 - 21.23), as was the overall response in the romiplostim group (p = 0.002, RR = 3.62, 95%CI = 1.63 - 8.03). Significant bleeding incidents (p = 0.49), overall adverse events (p = 0.71) and the need for rescue treatment (p = 0.13) were not statistically different between the romiplostim and placebo groups., Conclusions: Romiplostim might improve both durable and overall platelet response in children and adolescents with ITP, compared to a placebo. More clinical trials are needed to evaluate the efficacy and safety of romiplostim and to compare it with other second-line treatments that are being used in pediatric ITP., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (Copyright © 2022 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. All rights reserved.)

This study assessed the technical performance of a rapid lateral flow immunochromatographic assay (LFIA) for the detection of anti-SARS-CoV-2 IgG and compared LFIA results with chemiluminescent immunoassay (CLIA) results and an in-house enzyme immunoassay (EIA). To this end, a total of 216 whole blood or serum samples from three groups were analyzed: the first group was composed of 68 true negative cases corresponding to blood bank donors, healthy young volunteers, and eight pediatric patients diagnosed with other coronavirus infections. The serum samples from these participants were obtained and stored in a pre-COVID-19 period, thus they were not expected to have COVID-19. In the second group of true positive cases, we chose to replace natural cases of COVID-19 by 96 participants who were expected to have produced anti-SARS-CoV-2 IgG antibodies 30-60 days after the vaccine booster dose. The serum samples were collected on the same day that LFIA were tested either by EIA or CLIA. The third study group was composed of 52 participants (12 adults and 40 children) who did or did not have anti-SARS-CoV-2 IgG antibodies due to specific clinical scenarios. The 12 adults had been vaccinated more than seven months before LFIA testing, and the 40 children had non-severe COVID-19 diagnosed using RT-PCR during the acute phase of infection. They were referred for outpatient follow-up and during this period the serum samples were collected and tested by CLIA and LFIA. All tests were performed by the same healthcare operator and there was no variation of LFIA results when tests were performed on finger prick whole blood or serum samples, so that results were grouped for analysis. LFIA's sensitivity in detecting anti-SARS-CoV-2 IgG antibodies was 90%, specificity 97.6%, efficiency 93%, PPV 98.3%, NPV 86.6%, and likelihood ratio for a positive or a negative result were 37.5 and 0.01 respectively. There was a good agreement (Kappa index of 0.677) between LFIA results and serological (EIA or CLIA) results. In conclusion, LFIA analyzed in this study showed a good technical performance and agreement with reference serological assays (EIA or CLIA), therefore it can be recommended for use in the outpatient follow-up of non-severe cases of COVID-19 and to assess anti-SARS-CoV-2 IgG antibody production induced by vaccination and the antibodies decrease over time. However, LFIAs should be confirmed by using reference serological assays whenever possible.

Objectives: To compare demographic/clinical/laboratory/treatments and outcomes among children and adolescents with laboratory-confirmed coronavirus disease 2019 (COVID-19)., Methods: This was a cross-sectional study that included patients diagnosed with pediatric COVID-19 (aged <18 years) between April 11, 2020 and April 22, 2021. During this period, 102/5,951 (1.7%) of all admissions occurred in neonates, children, and adolescents. Furthermore, 3,962 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection samples were processed in patients aged <18 years, and laboratory-confirmed COVID-19 occurred in 155 (4%) inpatients and outpatients. Six/155 pediatric patients were excluded from the study. Therefore, the final group included 149 children and adolescents (n=97 inpatients and 52 outpatients) with positive SARS-CoV-2 results., Results: The frequencies of sore throat, anosmia, dysgeusia, headache, myalgia, nausea, lymphopenia, pre-existing chronic conditions, immunosuppressive conditions, and autoimmune diseases were significantly reduced in children and adolescents (p<0.05). Likewise, the frequencies of enoxaparin use (p=0.037), current immunosuppressant use (p=0.008), vasoactive agents (p=0.045), arterial hypotension (p<0.001), and shock (p=0.024) were significantly lower in children than in adolescents. Logistic regression analysis showed that adolescents with laboratory-confirmed COVID-19 had increased odds ratios (ORs) for sore throat (OR 13.054; 95% confidence interval [CI] 2.750-61.977; p=0.001), nausea (OR 8.875; 95% CI 1.660-47.446; p=0.011), and lymphopenia (OR 3.575; 95% CI 1.355-9.430; p=0.010), but also had less hospitalizations (OR 0.355; 95% CI 0.138-0.916; p=0.032). The additional logistic regression analysis on patients with preexisting chronic conditions (n=108) showed that death as an outcome was significantly associated with pediatric severe acute respiratory syndrome (SARS) (OR 22.300; 95% CI 2.341-212.421; p=0.007) and multisystem inflammatory syndrome in children (MIS-C) (OR 11.261; 95% CI 1.189-106. 581; p=0.035)., Conclusions: Half of the laboratory-confirmed COVID-19 cases occurred in adolescents. Individuals belonging to this age group had an acute systemic involvement of SARS-CoV-2 infection. Pediatric SARS and MIS-C were the most important factors associated with the mortality rate in pediatric chronic conditions with COVID-19.

Objectives: To prospectively evaluate demographic, anthropometric and health-related quality of life (HRQoL) in pediatric patients with laboratory-confirmed coronavirus disease 2019 (COVID-19)., Methods: This was a longitudinal observational study of surviving pediatric post-COVID-19 patients (n=53) and pediatric subjects without laboratory-confirmed COVID-19 included as controls (n=52) was performed., Results: The median duration between COVID-19 diagnosis (n=53) and follow-up was 4.4 months (0.8-10.7). Twenty-three of 53 (43%) patients reported at least one persistent symptom at the longitudinal follow-up visit and 12/53 (23%) had long COVID-19, with at least one symptom lasting for >12 weeks. The most frequently reported symptoms at the longitudinal follow-up visit were headache (19%), severe recurrent headache (9%), tiredness (9%), dyspnea (8%), and concentration difficulty (4%). At the longitudinal follow-up visit, the frequencies of anemia (11% versus 0%, p=0.030), lymphopenia (42% versus 18%, p=0.020), C-reactive protein level of >30 mg/L (35% versus 0%, p=0.0001), and D-dimer level of >1000 ng/mL (43% versus 6%, p=0.0004) significantly reduced compared with baseline values. Chest X-ray abnormalities (11% versus 2%, p=0.178) and cardiac alterations on echocardiogram (33% versus 22%, p=0.462) were similar at both visits. Comparison of characteristic data between patients with COVID-19 at the longitudinal follow-up visit and controls showed similar age (p=0.962), proportion of male sex (p=0.907), ethnicity (p=0.566), family minimum monthly wage (p=0.664), body mass index (p=0.601), and pediatric pre-existing chronic conditions (p=1.000). The Pediatric Quality of Live Inventory 4.0 scores, median physical score (69 [0-100] versus 81 [34-100], p=0.012), and school score (60 [15-100] versus 70 [15-95], p=0.028) were significantly lower in pediatric patients with COVID-19 at the longitudinal follow-up visit than in controls., Conclusions: Pediatric patients with COVID-19 showed a longitudinal impact on HRQoL parameters, particularly in physical/school domains, reinforcing the need for a prospective multidisciplinary approach for these patients. These data highlight the importance of closer monitoring of children and adolescents by the clinical team after COVID-19.

Leukocyte adhesion deficiency-III (LAD-III) is a rare genetic disease caused by defective integrin activation in hematopoietic cells due to mutations in the FERMT3 gene. The PTPRQ gene encodes the protein tyrosine phosphatase receptor Q and is essential for the normal maturation and function of hair bundle in the cochlea. Homozygous PTPRQ mutations impair the stereocilia in hair cells which lead to nonsyndromic sensorineural hearing loss (SNHL) with vestibular dysfunction. Here, we report two novel pathogenic homozygous mutations found in two genes, FERMT3 and PTPRQ , in a Brazilian patient with LAD-III and SNHL, which may develop our understanding of the phenotype-genotype correlation and prognosis of patients with these rare diseases., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)

Introduction: Little attention is given to thrombosis associated with pediatric acute promyelocytic leukemia (APL). This study describes the thrombotic and hemorrhagic manifestations of APL in pediatric patients and evaluates their hemostasis, based on coagulation tests., Methods: Inclusion criteria were age 0-18 years and APL diagnosis between April 2005 and November 2017. Patients who had received blood transfusion prior to coagulation tests were excluded. Baseline coagulation tests, hematologic counts, and hemorrhagic/thrombotic manifestations were evaluated., Results: Median age was 10.7 years (1-15 years). The initial coagulation tests revealed a median Hgb of 8.3 g/dL (4.7-12.9 g/dL), median leucocyte count of 10.9 × 10⁹/L (1.1-95.8 × 10⁹/L), median platelet count of 31.8 × 10⁹/L (2.0-109.0 × 10⁹/L), median activated partial thromboplastin time (aPTT) of 31.7 s (23.0-50.4 s), median aPTT ratio of 1.0 (0.78-1.6), median thromboplastin time (PT) of 17.5 s (13.8-27.7 s), median PT activity of 62% (25-95 %), and median fibrinogen of 157.7 mg/dL (60.0-281.0 mg/dL). Three patients (13%) had thrombosis. At diagnosis, 21 patients (91.3%) had bruising, one patient (4.3%) had splenic vein and artery thrombosis and one patient (4.3%) presented without thrombohemorrhagic manifestations. During treatment, two patients (8.6%) had thrombosis., Conclusion: Knowledge of thrombosis in pediatric APL is important to determine its risk factors and the best way to treat and prevent this complication., (Copyright © 2020 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. All rights reserved.)

Objective: To report a single-center experience with thrombolytic therapy using recombinant tissue plasminogen activator (rt-PA) in preterm neonates with severe thrombotic events, in terms of thrombus resolution and bleeding complications., Study Design: This retrospective study included 21 preterm neonates with severe venous thrombotic events admitted to the neonatal intensive care unit, identified in our pharmacy database from January 2001 to December 2016, and treated with rt-PA until complete or partial clot lysis, no-response or bleeding complications. Our primary outcome was thrombus resolution., Results: Twenty-one preterm neonates were treated with rt-PA for an average of 2.9 cycles. Seventeen patients (80.9%) had superior vena cava thrombosis and superior vena cava syndrome. All patients had a central venous catheter, parenteral nutrition, mechanical ventilation, and sepsis. Fifteen patients (71.4%) were extremely preterm, 11 (52.4%) were extremely low birth weight, and seven (33.3%) were very low birth weight. The patency rate was 85.7%, complete lysis occurred in 11 (52.4%) patients, and partial lysis in seven (33.3%). Minor bleeding occurred in five (23.8%) patients, three patients (14.2%) had clinically relevant nonmajor bleeding events, and major bleeding occurred in six (28%) patients., Conclusion: In this study, the rate of thrombus resolution in preterm neonates treated with rt-PA were similar to the percentages reported in children and adolescents, with a high rate of bleeding. Therefore, rt-PA thrombolytic therapy should only be considered as a treatment option for severe life-threatening thrombosis in premature neonates for whom the benefits of the thrombolytic treatment outweigh the risks of bleeding., (© 2020 Wiley Periodicals LLC.)

Aplastic anemia (AA) is a rare disorder characterized by suppression of bone marrow function, which can progress to myelodysplastic syndrome (MDS) or to acute myeloid leukemia (AML). To determine if there are characteristics in bone marrow biopsies in children and adults previously diagnosed with acquired AA, which could predict progression to MDS, we evaluated 118 hypocellular bone marrow biopsies from adults (76 patients) and children (42) diagnosed initially with acquired AA previously to any treatment. Histology was reviewed according to a detailed protocol including Bennett and Orazi criteria for hypocellular myelodysplastic syndrome (h-MDS) and Bauman et al. criteria for refractory cytopenia of childhood (RCC). Twelve patients (10.2%; 6 children and 6 adults) progressed to MDS after a median time of 56 months. Criteria described by Bennett and Orazi suggestive of h-MDS in bone marrow biopsies were detected in 16 cases (13.5%; 8 adults and 8 children), and none in patients that progressed to MDS/AML. Twenty adults' biopsies (26.3%) had the histological criteria used for the diagnosis of pediatric RCC, and none showed MDS/AML evolution. Ten children (23.8%) were reclassified morphologically as RCC, and only one progressed to MDS. In this population with acquired aplastic anemia (AAA), no histological/immunohistochemical (H/IHC) bone marrow findings could discriminate patients with higher risk for myeloid clonal progression, which questions the diagnosis of h-MDS/RCC based only on the finding of dysplasia in the cases without increased blasts and/or the characteristic genetic abnormalities., Competing Interests: Declaration of competing interest None of the authors have any conflict of interest to disclose regarding the current paper. The Institutional Review Board approved this retrospective study., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To carry out a review of the literature on adolescents' participation in decision making for their own health., Data Sources: Review in the Scientific Electronic Library Online (SciELO), Latin American and Caribbean Health Sciences Literature (LILACS) and PubMed databases. We consider scientific articles and books between 1966 and 2017. Keywords: adolescence, autonomy, bioethics and adolescence, autonomy, ethics, in variants in the English, Portuguese and Spanish languages. Inclusion criteria: scientific articles, books and theses on clinical decision making by the adolescent patient. Exclusion criteria: case reports and articles that did not address the issue. Among 1,590 abstracts, 78 were read in full and 32 were used in this manuscript., Data Synthesis: The age at which the individual is able to make decisions is a matter of debate in the literature. The development of a cognitive and psychosocial system is a time-consuming process and the integration of psychological, neuropsychological and neurobiological research in adolescence is fundamental. The ability to mature reflection is not determined by chronological age; in theory, a mature child is able to consent or refuse treatment. Decision-making requires careful and reflective analysis of the main associated factors, and the approach of this problem must occur through the recognition of the maturity and autonomy that exists in the adolescents. To do so, it is necessary to "deliberate" with them., Conclusions: International guidelines recommend that adolescents participate in discussions about their illness, treatment and decision-making. However, there is no universally accepted consensus on how to assess the decision-making ability of these patients. Despite this, when possible, the adolescent should be included in a serious, honest, respectful and sincere process of deliberation.

In a prospective randomized study, treatment for aplastic anemia (AA) with rabbit antithymocyte globulin (r-ATG) and cyclosporine showed inferior hematological response and survival in comparison to horse antithymocyte globulin (h-ATG) and cyclosporine. However, h-ATG was discontinued in most Asian, South American, and European countries, where r-ATG became the only ATG formulation available. We retrospectively evaluated consecutive patients with acquired AA who received either rabbit (n = 170) or horse (n = 85) ATG and cyclosporine for first-line treatment from 1992 to 2014 in seven referral centers in Brazil and Argentina. Overall response at 3 months was 17% (95%CI, 11-23%) for r-ATG and 44% (95%CI, 33-55%) for h-ATG (p < 0.001). At 6 months, it was 31% (95%CI, 34-39%) for r-ATG and 59% (95%CI, 48-69%) for h-ATG (p < 0.001). Overall survival at 5 years was 57% (95%CI, 47-65%) for r-ATG and 80% (95%CI, 69-87%) for h-ATG (log-rank = 0.001). Relapse was significantly higher in patients receiving h-ATG (28%; 95%CI, 17-43%) as compared to r-ATG (9.4%; 95%CI, 4-21%; log-rank, p = 0.01). The type of ATG was the only factor associated with both response and survival. The r-ATG dose varied from 1 to 5 mg/kg/day, but it did not correlate with outcomes. In summary, this is the largest multicenter study comparing the two ATG formulations in AA. Our results indicate that the dose of r-ATG does not influence hematologic response or survival in first-line therapy for acquired AA. Considering the toxicity and costs of r-ATG, our findings challenge its aggregate benefit to cyclosporine therapy and further strengthen that h-ATG should remain standard therapy in AA.

Despite being recommended as first-line immunosuppressive therapy in severe aplastic anemia (SAA), horse antithymocyte globulin (ATG) is still unavailable in many countries outside the USA. Rabbit ATG is more lymphocytoxic than horse ATG, and this might result in a higher incidence of severe infections and early mortality. This study was designed to identify the risk factors for early mortality and overall survival (OS) after rabbit ATG in patients with SAA. We retrospectively reviewed 185 patients with SAA who underwent rabbit ATG and cyclosporine. The incidence of death in 3 months following rabbit ATG therapy was 15.1% (28/185). Early mortality was mainly related to infectious complications, despite adequate antibiotic and/or antifungal treatment. Age > 35 years (odds ratio [OR] 5.06, P = 0.001) and baseline absolute neutrophil count (ANC) ≤ 0.1 × 10 9 /L (OR 7.64, P < 0.001) were independent risk factors for early mortality after immunosuppressive therapy with this agent. Hematological response at 6 months was observed in only 29.7% of all patients. OS at 1 year after rabbit ATG was 75.3%; and age > 35 years (OR 1.88, P = 0.03), baseline ANC ≤ 0.1 × 10 9 /L (OR 2.65, P < 0.001), and lack of response to rabbit ATG (OR 11.40, P < 0.001) were independently associated with mortality. Alternative strategies are needed for the treatment of SAA patients in countries were horse ATG is unavailable, particularly for those at high risk for early mortality after rabbit ATG due to a higher age and very low pre-treatment neutrophil count.

Objective: To evaluate the outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine as first-line treatment at this institution., Methods: Retrospective analysis of 26 pediatric patients with aplastic anemia, treated between 1996 and 2011 with rabbit antithymocyte globulin plus cyclosporine., Results: The overall response rate at six months was 34.6% (9/26), and the cumulative incidence of relapse was 26.5% (95% confidence interval [CI]: 1.4%-66%) at 5 years. The cumulative incidence of clonal evolution after immunosuppressive therapy was 8.3% (95% CI: 0.001%-53.7%) at five years with both clonal evolutions in non -responders who acquired monosomy 7 karyotype. The overall survival at five years was 73.6% (95% CI: 49.2%-87.5%)., Conclusions: The present results confirm the poor response rate with rabbit antithymocyte globulin as first therapy in pediatrics patients, similar to what has been reported for patients of all ages. This confirmation is problematic in Brazil, given the lack of horse antithymocyte globulin in many markets outside the United States., (Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.)

Essential thrombocythemia is an acquired myeloproliferative disorder characterized by the proliferation of megakaryocytes in bone marrow, leading to a persistent increase in the number of circulating platelets and thus increasing the risk for thrombotic and hemorrhagic events. The disease features leukocytosis, splenomegaly, vascular occlusive events, hemorrhages and vasomotor disorders. The intricate mechanisms underlying the molecular pathogenesis of this disorder are not completely understood and are still a matter of discussion. Essential thrombocythemia is an extremely rare disorder during childhood. We report on a case of essential thrombocythemia in a child and discuss the diagnostic approach and treatment strategy.