Characteristics and treatment results of refractory and relapsed acute myeloid leukaemia in paediatric patients treated in Polish Paediatric Leukaemia/Lymphoma Study Group institutions according to the Protocol Acute Myeloid Leukaemia Berlin-Frankfurt-Munster 2012 and a review of novel treatment possibilities in paediatric acute myeloid leukaemia

Introduction

This study aimed to present the clinical features and results of treatment of patients diagnosed with refractory or relapsed acute myeloid leukaemia (AML) in Polish Paediatric Leukaemia/Lymphoma Study Group (PPL/LSG) institutions, treated in accordance with the Protocol Acute Myeloid Leukaemia Berlin-Frankfurt-Munster 2012, as their first-line therapy.

Material and methods

The outcome data of 10 patients with refractory AML (median age 9.5 years) and 30 with relapsed AML (median age 12 years) were analysed retrospectively. Re-induction was usually based on idarubicin, fludarabine, and cytarabine along with allogeneic haematopoietic stem cell transplant (allo-HSCT) in 5 patients with refractory AML and 7 relapsed AML children.

Results

37.5% (3/8) of refractory AML patients achieved second complete remission second complete remission (CRII). One of ten patients (1/10; 10%) was alive and stayed in complete remission for 34 months after the allo-HSCT. The probability of 3-year event-free survival (pEFS) in this group was 0.125 ±0.11. In the group of relapsed AML patients, the CRII was achieved in 9 patients (34%), and the probability of survival was: pEFS = 0.24 ±0.08; probability overall survival (pOS) = 0.34 ±0.09, with significantly better results achieved in patients who underwent allo-HSCT (pOS = 0.54 ±0.14 vs. 0.08 ±0.08, p < 0.0001).

Conclusions

The prognosis of refractory AML and the first AML recurrence in children who were first-line treated in PPL/LSG centres according to Protocol Acute Myeloid Leukaemia Berlin-Frankfurt-Munster 2012 is poor. Failures of re-induction treatment particularly result from difficulties in achieving remission. Allogeneic HSCT improves prognosis in children with refractory and first recurrent AML, under the condition it is performed in complete remission. Novel therapeutic approaches are needed to increase the remission rate and improve the outcomes.

Characteristics and Outcome of FLT3-ITD-Positive Pediatric Acute Myeloid Leukemia-Experience of Polish Pediatric Leukemia and Lymphoma Study Group from 2005 to 2022

BACKGROUND

The FMS-like tyrosine kinase 3 (FLT3) gene mutated in 10-15% of pediatric acute myeloid leukemia (AML) is associated with an inferior outcome. The aim of the study was to analyze the outcome and characteristics of FLT3-ITD-positive pediatric AML.

METHODS

We retrospectively analyzed the nationwide pediatric AML database from between 2005 and 2022. FLT3-ITD was found in 54/497 (10.7%) patients with available analysis. Three consecutive treatment protocols were used (AML-BFM 2004 Interim, AML-BFM 2012 Registry, AML-BFM 2019 recommendations).

RESULTS

Probabilities of 5-year overall (OS), event-free (EFS) and relapse-free survival were significantly lower in the FLT3-ITD-positive patients compared to FLT3-ITD-negative (0.54 vs. 0.71, p = 0.041; 0.36 vs. 0.59, p = 0.0004; 0.47 vs. 0.70, p = 0.0029, accordingly). An improvement in the outcome was found in the analyzed period of time, with a trend of better survival in patients treated under the AML-BFM 2012 and AML-BFM 2019 protocols compared to the AML-BFM 2004 protocol (5-year EFS 0.52 vs. 0.27, p = 0.069). There was a trend of improved outcomes in patients treated with FLT3 inhibitors (n = 9, 2-year EFS 0.67 vs. 0.33, p = 0.053) and those who received stem cell transplantation (SCT) (n = 26; 5-year EFS 0.70 vs. 0.27, p = 0.059). The co-occurrence of the WT1 mutation had a dismal impact on the prognosis (5-year EFS 0.23 vs. 0.69, p = 0.002), while the NPM1 mutation improved survival (5-year OS 1.0 vs. 0.44, p = 0.036).

CONCLUSIONS

It seems that SCT and FLT3 inhibitors have a beneficial impact on the prognosis. Additional genetic alterations, like the WT1 and NPM1 mutations, significantly influence the outcome.

Ultrasound, laboratory and histopathological insights in diagnosing papillary thyroid carcinoma in a paediatric population: a single centre follow-up study between 2000-2022

Background

Papillary thyroid carcinoma (PTC) often coincides with autoimmune thyroiditis (AIT); whether this association is incidental or causal remains debated.

Objective

To evaluate the ultrasonographic, laboratory, and histopathological features of PTC in paediatric patients with and without AIT and its relationship to puberty.

Design

A retrospective cohort study.

Patients and methods

A retrospective analysis of medical records of 90 patients (69; 76.7% females). The mean age at PTC diagnosis was 13.8 years [range 6-18]. All patients were evaluated ultrasonographically before thyroid surgery. Thyroid nodules were categorised using the European Thyroid Imaging Reporting and Data System (EU-TIRADS PL), and cytopathology was assessed using Bethesda criteria. Neck ultrasound results and thyroid and autoimmune status were correlated with histopathological PTC assessment.

Results

The coexistence of PTC and AIT was found in 48.9% (44/90) of patients. The percentage of AIT was increasing with age; AIT was present only in 1/3 of prepubertal, close to 50% in pubertal, and over 60% in adolescent patients. The youngest patients (aged <10 years old) presented more often with goitre and lymphadenopathy and less often with AIT than adolescents (15-18 years of age). There were no differences in TPOAb, TgAb, and TSH levels between the age subgroups. Presurgical TgAb levels were higher than those of TPOAb in the youngest patients. Histopathological analysis revealed that the solid subtype was observed more often in prepubertal children and diffuse sclerosing in children below 14 years of age, whereas the classic subtype dominated in late pubertal. Univariate and multivariate analyses revealed that lymph nodes metastases (LNM) were associated with PTC diameter and fT4 level, whereas extrathyroidal extension with age and angioinvasion with PTC diameter and age. The correlations between age and fibrosis, and the presence of psammoma bodies in malignant tissues were close to significant. We did not observe an association between TSH levels and the presence of autoimmunity and PTC variables.

Conclusions

In paediatric patients the natural course of PTC may be less aggressive in adolescent patients than in younger children (especially < 10 years of age). We suggest that pre-operative evaluation of paediatric patients with thyroid nodules could include apart from assessment of thyroid hormones, evaluation of TPOAb, TgAb, and TRAb together with comprehensive neck ultrasonography.

Clinical Characteristics and Treatment Outcomes of Myeloid Sarcoma in Children: The Experience of the Polish Pediatric Leukemia and Lymphoma Study Group

Introduction

Myeloid sarcoma (MS) is an extramedullary malignant tumor composed of immature myeloid cells. It occurs in patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or chronic myeloid leukemia (CML). MS may coincide with disease diagnosis or precede bone marrow involvement by months or even years; it can also represent the extramedullary manifestation of a relapse (1, 2).

Aim

The aim of this study is to describe clinical characteristics of children diagnosed with MS in Poland as well as to analyze diagnostic methods, treatment, and outcomes including overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS). The study also attempted to identify factors determining treatment outcomes.

Patients

The study group comprised 43 patients (F=18, M=25) aged 0-18 years (median age, 10.0 years; mean age, 8.8 years) diagnosed with MS based on tumor biopsy and immunohistochemistry or identification of underlying bone marrow disease and extramedullary tumor according to imaging findings.

Methods

The clinical data and diagnostic and therapeutic methods used in the study group were analyzed. A statistical analysis of the treatment outcomes was conducted with STATISTICA v. 13 (StatSoft, Inc., Tulsa, OK, USA) and analysis of survival curves was conducted with MedCalc 11.5.1 (MedCalc Software, Ostend, Belgium). Statistical significance was considered at p&lt;0.05.

Results

In the study group, MS was most frequently accompanied by AML. The most common site of involvement was skin, followed by orbital region. Skin manifestation of MS was more common in the age group &lt;10 years. The most frequent genetic abnormality was the t(8;21)(q22;q22) translocation. The 5-year OS probability (pOS), 5-year RFS probability (pRFS), and 5-year EFS probability (pEFS) were 0.67 ± 0.08, 0.79 ± 0.07, and 0.65 ± 0.08, respectively. In patients with isolated MS and those with concurrent bone marrow involvement by AML/MDS, pOS values were 0.56 ± 0.12 and 0.84 ± 0.09 (p=0.0251), respectively, and pEFS values were 0.56 ± 0.12 and 0.82 ± 0.08 (p=0.0247), respectively. In patients with and without the t(8;21)(q22;q22) translocation, pEFS values were 0.90 ± 0.09 and 0.51 ± 0.14 (p=0.0490), respectively.

Conclusions

MS is a disease with a highly variable clinical course. Worse treatment outcomes were observed in patients with isolated MS compared to those with concurrent bone marrow involvement by AML/MDS. Patients with the t(8;21)(q22;q22) translocation were found to have significantly higher pEFS. MS location, age group, chemotherapy regimen, surgery, and/or radiotherapy did not have a significant influence on treatment outcomes. Further exploration of prognostic factors in children with MS is indicated.

Advances in the First Line Treatment of Pediatric Acute Myeloid Leukemia in the Polish Pediatric Leukemia and Lymphoma Study Group from 1983 to 2019

Simple Summary

We retrospectively analyzed the results of the five consecutive treatment protocols for pediatric acute myeloid leukemia (AML) used in Poland from 1983 to 2019 (excluding promyelocytic, secondary, biphenotypic, and Down syndrome AML). The study included 899 children. The probability of three-year overall, event-free, and relapse-free survival increased from 0.34 ± 0.03 to 0.75 ± 0.05, 0.31 ± 0.03 to 0.67 ± 0.05, and 0.52 ± 0.03 to 0.78 ± 0.05, respectively. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24) who were treated in the AML-BFM 2012 Registry, while an unsatisfactory outcome was found in patients with FLT3-ITD. The use of standardized therapeutic protocols with the successive consideration of genetic prognostic factors and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.

Abstract

Background: From 1983, standardized therapeutic protocols for pediatric acute myeloid leukemia (AML) based on the BFM group experience were introduced in Poland. We retrospectively analyzed the results of pediatric AML treatment in Poland from 1983 to 2019 (excluding promyelocytic, therapy-related, biphenotypic, and Down syndrome AML). Methods: The study included 899 children suffering from AML treated with the following: AML-PPPLBC 83 (1983–1993, n = 187), AML-PPGLBC 94 (1994–1997, n = 74), AML-PPGLBC 98 (1998–2004, n = 151), AML-BFM 2004 Interim (2004–2015, n = 356), and AML-BFM 2012 (2015–2019, n = 131). Results: The probability of three-year overall survival was 0.34 ± 0.03, 0.37 ± 0.05, 0.54 ± 0.04, 0.67 ± 0.03, and 0.75 ± 0.05; event-free survival was 0.31 ± 0.03, 0.34 ± 0.05, 0.44 ± 0.04, 0.53 ± 0.03, and 0.67 ± 0.05; and relapse-free survival was 0.52 ± 0.03, 0.65 ± 0.05, 0.58 ± 0.04, 0.66 ± 0.03, and 0.78 ± 0.05, respectively, in the subsequent periods. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients treated with AML-BFM 2012 with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24), while unsatisfactory outcomes were found in the patients with FLT3-ITD. Conclusions: The use of standardized, systematically modified therapeutic protocols, with the successive consideration of genetic prognostic factors, and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.

The Expression of Genes Related to Lipid Metabolism and Metabolic Disorders in Children before and after Hematopoietic Stem Cell Transplantation-A Prospective Observational Study

Metabolic disorders in children after hematopoietic stem cell transplantation (HSCT) are poorly characterized. However, it is known that dyslipidemia and insulin resistance are particularly common in these patients. We conducted a prospective study of 27 patients treated with HSCT to assess the possibility of predicting these abnormalities. We measured gene expressions using a microarray technique to identify differences in expression of genes associated with lipid metabolism before and after HSCT. In patients treated with HSCT, total cholesterol levels were significantly higher after the procedure compared with the values before HSCT. Microarray analysis revealed statistically significant differences in expressions of three genes, DPP4, PLAG1, and SCD, after applying the Benjamini-Hochberg procedure (pBH < 0.05). In multiple logistic regression, the increase of DPP4 gene expression before HCST (as well as its change between pre- and post-HSCT status) was associated with dyslipidemia. In children treated with HSCT, the burden of lipid disorders in short-term follow-up seems to be lower than before the procedure. The expression pattern of DPP4 is linked with dyslipidemia after the transplantation.

Methylation and Expression of FTO and PLAG1 Genes in Childhood Obesity: Insight into Anthropometric Parameters and Glucose-Lipid Metabolism

The occurrence of childhood obesity is influenced by both genetic and epigenetic factors. FTO (FTO alpha-ketoglutarate dependent dioxygenase) is a gene of well-established connection with adiposity, while a protooncogene PLAG1 (PLAG1 zinc finger) has been only recently linked to this condition. We performed a cross-sectional study on a cohort of 16 obese (aged 6.6-17.7) and 10 healthy (aged 11.4-16.9) children. The aim was to evaluate the relationship between methylation and expression of the aforementioned genes and the presence of obesity as well as alterations in anthropometric measurements (including waist circumference (WC), body fat (BF_kg) and body fat percent (BF_%)), metabolic parameters (lipid profile, blood glucose and insulin levels, presence of insulin resistance) and blood pressure. Expression and methylation were measured in peripheral blood mononuclear cells using a microarray technique and a method based on restriction enzymes, respectively. Multiple regression models were constructed to adjust for the possible influence of age and sex on the investigated associations. We showed significantly increased expression of the FTO gene in obese children and in patients with documented insulin resistance. Higher FTO expression was also associated with an increase in WC, BF_kg, and BF_% as well as higher fasting concentration of free fatty acids (FFA). FTO methylation correlated positively with WC and BF_kg. Increase in PLAG1 expression was associated with higher BF%. Our results indicate that the FTO gene is likely to play an important role in the development of childhood adiposity together with coexisting impairment of glucose-lipid metabolism.

Treatment Outcome and the Genetic Characteristics of Acute Promyelocytic Leukemia in Children in Poland From 2005 to 2018

Background: The aim of the study was to analyze the treatment outcome and genetic characteristics of acute promyelocytic leukemia (APL) in children in Poland from 2005 to 2018. Methods: All 41 patients diagnosed with APL in Poland during the analysis period were eligible for the study. In period I (2005-2015), 33 patients were treated with chemotherapy and all-trans retinoic acid (ATRA), and in period II (2015-2018), 3 patients (high risk) received induction chemotherapy with ATRA and arsenic trioxide (ATO), and 5 patients (standard risk) received ATRA and ATO without chemotherapy. Results: Probability of 5-years overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS) was 0.819 ± 0.069, 0.831 ± 0.063, and 0.961 ± 0.037, respectively, in the whole cohort. Four (11%) early deaths were observed. One patient died of severe infection in the course of disease progression. Relapse occurred in one patient, who died finally because of disease progression. All events occurred in the patients from period I. Variant APL was identified in one patient (successfully treated with chemotherapy with ATRA) and complex translocation in one patient (the only patient with relapse). Additional chromosomal aberrations were found in 26% of patients and FLT3-ITD mutation was detected in 44% of patients; none of those changes influenced clinical outcome. Conclusion: Treatment outcome in the analyzed group is similar to the results reported by other study groups. The main cause of death was coagulation disorders in the early stage of disease. Early, accurate diagnosis followed by specific treatment enables the reduction in the number of early deaths.

[Mobilization and collection of hematopoietic stem cells in children with different neoplastic diseases for autotransplantation to support high dose chemotherapy (single centre experience)]

Currently, granulocyte colony stimulating factor (G-CSF) alone or in combination with myelosuppresive chemotherapy remain the standards of CD34+ cells mobilization allows the safe and successful collection of adequate peripheral blood stem cells (PBSC) for autologous transplantation. However, in up to 30% of patients mobilization of PBSC is ineffective. This report presents our experience in mobilization and collection of peripheral blood stem cells in 82 children with different proliferative disease. In mobilization G-CSF was administered alone in steady state (56 patients, pts) or in combination with myelosuppresive chemotherapy (26 pts). The CD34+ cell count at least 10 cells/ml was required to start apheresis procedure, which was repeated, if needed, during following 1-4 days until collection of at least 2 (optimally 3) x106 CD34+ cells/kg b.w. of recipient was obtained. Three pts in each group (3/ 56 and 3/26) failed the first course of mobilization. The median number of CD34+ cells mobilized was 4.8 (0.5-15) x106/kg b.w. The minimal and optimal number of CD34+ cells for transplantation was achieved in 85% and 61% of patients in the G-CSF + chemotherapy group and in 84% and 54% in the G-CSF group, respectively. The efficacy of presented mobilization arms in our group was similar. However, the incidence of infection and total hospitalization time during mobilization were higher in chemotherapy + G-CSF group.

[Hemophagocytic syndrome in children with different underlying conditions]

Hemophagocytic syndrome (HS) is a life-threatening condition of hyperinflammation. Main symptoms are: prolonged fever, cytopenia, hepatosplenomegaly, hemophagocytosis, hyperferritinemia, hypertriglyceridemia and hypofibrinogenemia. Primary genetic form and secondary HS associated with infections, malignancies or autoimmune disorders can be distinguished. Untreated HS in most cases leads to death. We analyzed retrospectively 7 cases of HS in children (3 girls, 4 boys; aged 10 days -14 years) treated in 3 different pediatric centers from 2004 to 2009. In 3 cases HS was associated with infections (EBV, CMV, Bacillus Calmette Guerin - BCG), in 1 child with non-Hodgkin anaplastic large cell lymphoma (ALCL), in 1 patients probably with side effect of antiepileptic drug. In 2 cases cause of HS remained unknown. Fever, hepatomegaly, pan- or bicytopenia and hyperferritinemia were present in all children. In addition, splenomegaly was noted in 6 cases, hemophagocytosis in 6 children, impaired function or decreased number of NK cells in 4 cases, hypofibrino-genemia in 5 and hypotriglyceridemia in 4 patients. Among other symptoms and signs we observed: lymphadenopathy, hepatic failure, oedema, rash, neurological symptoms, increased level of LDH and inflammatory markers. In one child acute pancreatitis occurred. Among others, antibiotics, antiviral and immunosuppressive drugs were used in therapy. HLH-2004 protocol was applied in 4 cases. Patient with ALCL was treated with chemotherapy and allogeneic stem cell transplantation. Four patients are alive, 2 died because of HS, child with ALCL died because of generalized infection in peritrans-plantation period. In case of prolonged fever, splenomegaly and cytopenia diagnosis of HS should be considered. Following tests are recommended: complete blood count, ferritin, triglycerides, fibrinogen, bone marrow aspiration and NK cell assessment. Patients should be also screened for infections and malignancies. Early diagnosis of HS and underlying condition is crucial to start lifesaving therapy.

[Evaluation of colonization by multidrug-resistant organisms and infections' frequency in chronically and incurably ill children under care of the Cracow children's Hospice of Father J. Tischner]

Infections are one of the most important clinical problem and most frequent cause of interventions among chronically ill children under hospice care. Frequent and long-lasting hospitalizations before admission to the hospice cause patients' colonization with nosocomial pathogens. These pathogens usually cause returning infections, difficult to cure in home care. The aim of the study was evaluation of colonization by multidrug-resistant organisms and infections' frequency in chronically and incurably ill children under care of the Cracow Children's Hospice of Father J. Tischner. We analyzed infections in patients of the Hospice in 2008-2009. Frequency of infections, their localization, pathogens and necessity of hospitalization were evaluated. On the basis of microbiological examination we distinguished infections caused by multidrug resistant pathogens. Ninety microbiological examination were made in 24 children. Urine, stool, pharyngeal and nasal swap and others were examined. Nosocomial pathogens including Gram-negative rods with ESBL phenotype, Gram-positive Enterococci with HLAR phenotype and Staphylococci with MRCNS and MRSA phenotype were isolated in 36 (40%) examinations, in 17 (71%) patients. Frequency of infections was higher in patients colonized by nosocomial pathogens in comparison with patients without colonization, but difference was not statistically important. There are many factors that increase risk of infections and make them difficult to treat, like: immobilization, impaired swallowing and coughing reflexes, thorax deformation, neurogenic bladder, tracheostomy. Multi-drug resistant pathogens are additional risk factor that can lead to the necessity of hospitalization. In chronically and incurably ill patients time of hospitalization should be minimized to reduce the risk of colonization with multi-drug resistant pathogens.

[Anaplastic large cell lymphoma associated with hemophagocytic lymphohistiocytosis: a case report and review of the literature]

Malignancy-associated hemophagocytic syndrome has been reported mostly in adults, in children it is very rare. It can develop before or during treatment, in association with an infection or without a known triggering factor. Here we present a case report of a 14 years old boy diagnosed with HLH before recognition of anaplastic large cell lymphoma (ALCL). Because of progression of symptoms characteristic for HLH, therapy according to the HLH 2004 protocol was introduced. Finally, histopathological examination of a subsequently excised enlarged lymph node demonstrated lesions typical for ALCL. First-line therapy, according to protocol for this type of lymphoma, was introduced. Because of resistance to standard therapy, change of protocol was necessary. Finally the patients achieved complete remission. He was qualified for allogeneic stem cell transplantation. The patient died in peritransplantation period because of infection complications. Occurrence of HLH can cause diagnostic difficulties, because it often masks the underlying disease, especially when it is associated with infection. Therefore, each case of HLH requires accurate evaluation for malignancy. Poor outcome in patients with malignancy-associated HLH is emphasized in the literature. There is necessity of establishment of more effective therapy.

[An economic consideration of the lower respiratory tract infection treatment in children with severe neurodegradative diseases under the hospice care]

Congenital and acquired neurodegradative diseases are always the reason for prolonged stay in hospital, at the beginning of the establishment of diagnosis and treatment and afterwards for stabilizing all functional adaptation to an existence with the severe disability. Also infections of the lower respiratory tract accompanying the later course of the disease are usually directed to hospital treatment. The aim of the study was to delineate the role of hospice care of patients staying at home, in economical approach to the medical care of severly and incurably ill children. The study group consisted of 29 children with neurodegradative diseases, aged 6 months to 18 years, admitted to the home care of Priest Józef Tischner Cracovian Children' Hospice. The costs of yearly treatment (based on 2008 data) of the infections of the lower airways in the studied group, performed at home under the hospice care and in hospital, were compared. The actual expenses of home treatment were counted. Considering the hospital therapy costs, the simulation was performed following median expenses of a 10-day-treatment of a 20 kg-in-weight child with uncomplicated lower respiratory tract infection in pediatric department with the use of the first line therapy antibiotic. Three parameters were taken to calculations: the medical care costs, the expenses of laboratory tests and X-ray pictures and the costs of antibiotics. In studied children 61 cases of lower respiratory tract infections were diagnosed in 2008 (the median incidence was 2,1 per year; ranged 0-7), of which 48 cases were treated at home. The median time of antibiotics administration in home treatment was 13 days. In 31% of infections more than one antibiotic was used. In 19% of cases in home therapy parenteral medicine was necessary. The median summarized cost of treat- ment at home was calculated as 2657 zl. The need for hospital care in our group concerned 13 incidences. The median estimated cost of treatment of the lower airways infection in hospital for one child equaled 4942 zl. The expenses of home treatment of the lower airways infections under the hospice care were twice lower than the costs of the therapy in hospital. Apart from the obvious psychological and social benefits, also economic aspect contributes to the promotion of the hospice care of staying-at-home patient in the improvement of medical care for children with severe neurodegradative diseases.

[Hemophagocytic lymphohistiocytosis: diagnostic problems in pediatrics]

Hemophagocytic lymphohistiocytosis (HLH), also known as hemophagocytic syndrome (HS), is a life-threatening hyperinflammatory condition caused by uncontrolled proliferation of activated lymphocytes and histiocytes producing excessively proinflammatory cytokines. HLH can occur in all age groups. The most common syndromes are: prolonged fever, hepatosplenomegaly, unspecific neurological symptoms, pancytopenia, hemophagocytosis. Characteristic biochemical markers include high triglycerides, ferritin and decreased fibrinogen. There are two forms of HLH, primary (genetic) and acquired (secondary to infections, malignant and autoimmune diseases). Occurrence of both forms of HLH, acquired and genetic, is induced by infections, usually viral or by other triggering agents. Despite established diagnostic criteria many cases probably remain unrecognized. The main diagnostic difficulty is low specificity of symptoms, and in secondary form contemporary occurrence of symptoms of underlying disease. The aim of HLH treatment is to suppress hyperinflammation, what can be achieved by use of immunosuppressive/immunomodulating agents or cytostatics. Patients with genetic form of HLH require hematopoietic stem cell transplantation. Awareness of the symptoms and diagnostic criteria of HLH is important for early diagnosis and immediate application of life-saving therapy.

[Hemophagocytic syndrome: diagnostic problems]

Hemophagocytic syndrome (HS) is a rare but life-threatening disease caused by inappropriate activation of T-lymphocytes and histiocytes, hipercytokinemia and hemophagocytosis. The most common symptoms are fever, hepatosplenomegaly, unspecific neurological abnormalities, pancytopenia, coagulopathy, hiperferritinemia and lipid abnormalities. HS is classified into two forms: primary, inherited (Familial Hamophagocytic Lymphohistiocytosis--FHL) and secondary (associated with infection, malignancy, autoimmune disease). In spite of the fact that diagnostic guidelines are available it often remains unrecognised. Prognosis of HS depends on the form of disease and in case of secondary HS on the underlying disease. Development of the treatment protocols (HLH-94, HLH-2004) which combine immunochemiotherapy with hematopoietic stem cell transplantation has strongly improved prognosis in HS especially in the primary form. Three-year overall survival for children with HS is now over 50%. Early diagnosis and appropriate therapy is crucial for effectiveness of the treatment. Popularisation of the knowledge about the syndrome, diagnostic guidelines and treatment protocols can contribute to more frequent appropriate recognition of HS and to improvement of the treatment results.

[Significance of L-asparaginase activity and biochemical parameters evaluation in children with acute lymphoblastic leukemia]

L-asparaginase is one of the most important agent used in multidrug chemotherapy regimens in the treatment of malignancies which derive from lymphoid system (acute lymhoblastic leukemias and non-hodgkin lymphoma). L-asparaginase leads to enzymatic cleavage of L-asparagine (amino acid essential for lymphoblasts' growth) to ammonia and L-aspartic acid, what results in depletion of L-asparagine in a serum and cerebrospinal fluid, and finally leads to destruction of lymphoblasts, which lack ability of endogenic L-asparagine production. In the course of L-asparaginase therapy severe side effects could be observed such as: coagulation disturbances, acute pancreatitis, anaphilactic shock and other types of allergic reaction, as well as liver and CNS failure. Monitoring of L-asparaginase activity in serum is recomended in order to optimalize therapy with L-asparaginase and reducing risk of severe side effects. Continuous assessment of L-asparaginase activity during therapy gives also opportunity to detect asymptomatic inactivation of L-ASPA - so called "silent inactivation", which is cused by production of antibodies against xenogenic protein, especcialy in IgG class. This process leads to shortening of half-life of L-ASPA. The paper shows presently available monitoring methods during therapy with L-ASPA, with all their pros and cons.

[The assessment of efficacy of hepatitis B prophylaxis in children with acute lymphoblastic leukemia]

The aim of the study was to evaluate the efficacy of hepatitis B prophylaxis in children with acute lymphoblastic leukemia (ALL) and to try to determine the optimal procedure of protection against the infection. The retrospective analysis included 229 patients with ALL divided into three groups depending on the type of anti-HBV prophylaxis. The group 1 (1990-91, 38 patients) received only sporadically passive prophylaxis, in the group 2 (1992-94, 55 patients) passive prophylaxis was regular, and the patients of the group 3 (1995-2001, 138 children) received complete active and passive prophylaxis. Among vaccinated children three subgroups were additionally distinguished: subgroup a--vaccination was completed before the disease, subgroup b--the cycle of vaccination began before and continued during the therapy, subgroup c--the whole cycle of vaccination was performed during the ALL treatment. The efficacy of the prophylaxis was evaluated taking into account the incidence of hepatitis B and the level of anti-HBs antibodies in vaccinated children. Additionally the incidence of hepatitis C was assessed to evaluate the role of unspecific prophylaxis. The incidence of hepatitis B in the group 1, 2, and 3 was: 57.9%, 23.6%, and 0.76%, respectively, and the incidence of hepatitis C: 44.7%, 36.4%, and 5.9%, respectively. The percent of the failure of active prophylaxis in the subgroup a, b, and c was: 29%, 53%, and 93%, respectively. In spite of the reduction of exposure to the infection (unspecific prophylaxis), the role of specific prophylaxis is essential. The program of passive and active prophylaxis used by us is efficient in preventing hepatitis B in children with ALL. However, during the intensive chemotherapy only passive prophylaxis should be used with postponement of the vaccination because of very low response to the vaccination applied in this phase of treatment. Regular control of anti-HBs antibodies' level is essential in all patients with leukemia even in those with initially high level of antibodies.