Contributions
Abstract: PB2290
Type: Publication Only
Background
Essential thrombocythemia (ET) is a disorder of adult-aged patients. The incidence in adults is 2/100 000 per year, but is approximately 1/10 000 000 per year in children. The low incidence recorded in children suggests that the biology of the disease could be different compared with the adult forms. Furthermore, ET can present in pediatric age as sporadic or familial diseases.
Aims
Analysis of etiology and clinical course of primary and secondary thrombocytosis in children.
Methods
Retrospective analysis was performed in 127 children (68 boys and 59 girls at the age of 5-10 years) with a diagnosis of thrombocytosis, observed between 2013 and 2017 at the Belarusian Research Center for pediatric oncology, hematology and immunology. The study was participated by all patients who were found thrombocytosis over 500 х109/L (platelet count 680-1200 х109/L).
Results
Among all patients, 122 children (96%) had secondary thrombocytosis (median platelet count 774 (680…940) х109/L), which is a result of excessive megacariopoyesis and thrombopoiesis in the course of various disorders, both hematologic and non-hematologic. The most common causes of secondary thrombocytosis were infections: viral (cytomegalovirus, parvovirus B19, herpesvirus type VI) and bacterial (Staphylococcus aureus, Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Haemophilus influenzae, Streptococcus pyogenes, Streptococcus pneumoniae, Pseudomonas aeruginosa), bleeding (Crohn's disease, gastric and intestinal ulcers) and iron deficiency anemia. In all cases of secondary thrombocytosis, the platelet number normalized after curing the underlying diseases during the 2-14 month period. Other 5 patients (4%) after elimination of the relationship of thrombocytosis with taken medication and after elimination of the foci of infection in case of suspicion of primary thrombocytosis (median platelet count 1027 (925…1200) х109/L), performed myelogram, cytogenetic and molecular examination of bone marrow. Cytological study of the bone marrow: hypercellular bone marrow, increased proliferation of megakaryocytes (MK), with an increase in the number of large mature cells. Cells of the erythroid and myeloid lines are within normal limits. There is no shift towards unripe forms. Histological examination of the bone marrow showed an increase in the number of MK, large MK with excessive cytoplasm and a hyperbular nucleus. Molecular examination of bone marrow found a JAK2 V617F mutation in all 5 children with ET. Other types of mutations, characteristic of myeloproliferative diseases, are not identified. All patients with ET had not familial MPD. Because criteria for the treatment of ET are not specific for children, therapeutic choices are highly heterogeneous. Specific treatment included interferon alfa and hydroxyurea, and low-dose aspirin. In all the analyzed cases of ET in children, no clinical symptoms of disorders of hemostasis were ound. No patient experienced thromboembolic complications associated with thrombocytosis.
Conclusion
Myeloproliferative marker a JAK2 V617F mutation, and clonal hemopoiesis assay, are useful diagnostic tests in children with sporadic forms ET. Larger samples are obviously needed and of biologic markers to conclusions for diagnosis and treatment of ET in children.
Session topic: 16. Myeloproliferative neoplasms - Clinical
Keyword(s): Children, Essential Thrombocytemia, Secondary, Thrombocytosis
Abstract: PB2290
Type: Publication Only
Background
Essential thrombocythemia (ET) is a disorder of adult-aged patients. The incidence in adults is 2/100 000 per year, but is approximately 1/10 000 000 per year in children. The low incidence recorded in children suggests that the biology of the disease could be different compared with the adult forms. Furthermore, ET can present in pediatric age as sporadic or familial diseases.
Aims
Analysis of etiology and clinical course of primary and secondary thrombocytosis in children.
Methods
Retrospective analysis was performed in 127 children (68 boys and 59 girls at the age of 5-10 years) with a diagnosis of thrombocytosis, observed between 2013 and 2017 at the Belarusian Research Center for pediatric oncology, hematology and immunology. The study was participated by all patients who were found thrombocytosis over 500 х109/L (platelet count 680-1200 х109/L).
Results
Among all patients, 122 children (96%) had secondary thrombocytosis (median platelet count 774 (680…940) х109/L), which is a result of excessive megacariopoyesis and thrombopoiesis in the course of various disorders, both hematologic and non-hematologic. The most common causes of secondary thrombocytosis were infections: viral (cytomegalovirus, parvovirus B19, herpesvirus type VI) and bacterial (Staphylococcus aureus, Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Haemophilus influenzae, Streptococcus pyogenes, Streptococcus pneumoniae, Pseudomonas aeruginosa), bleeding (Crohn's disease, gastric and intestinal ulcers) and iron deficiency anemia. In all cases of secondary thrombocytosis, the platelet number normalized after curing the underlying diseases during the 2-14 month period. Other 5 patients (4%) after elimination of the relationship of thrombocytosis with taken medication and after elimination of the foci of infection in case of suspicion of primary thrombocytosis (median platelet count 1027 (925…1200) х109/L), performed myelogram, cytogenetic and molecular examination of bone marrow. Cytological study of the bone marrow: hypercellular bone marrow, increased proliferation of megakaryocytes (MK), with an increase in the number of large mature cells. Cells of the erythroid and myeloid lines are within normal limits. There is no shift towards unripe forms. Histological examination of the bone marrow showed an increase in the number of MK, large MK with excessive cytoplasm and a hyperbular nucleus. Molecular examination of bone marrow found a JAK2 V617F mutation in all 5 children with ET. Other types of mutations, characteristic of myeloproliferative diseases, are not identified. All patients with ET had not familial MPD. Because criteria for the treatment of ET are not specific for children, therapeutic choices are highly heterogeneous. Specific treatment included interferon alfa and hydroxyurea, and low-dose aspirin. In all the analyzed cases of ET in children, no clinical symptoms of disorders of hemostasis were ound. No patient experienced thromboembolic complications associated with thrombocytosis.
Conclusion
Myeloproliferative marker a JAK2 V617F mutation, and clonal hemopoiesis assay, are useful diagnostic tests in children with sporadic forms ET. Larger samples are obviously needed and of biologic markers to conclusions for diagnosis and treatment of ET in children.
Session topic: 16. Myeloproliferative neoplasms - Clinical
Keyword(s): Children, Essential Thrombocytemia, Secondary, Thrombocytosis