An unusual long-term outcome of a child with primary myelofibrosis harboring a JAK2 mutation

Childhood Primary Myelofibrosis Presented with Headache, Splenomegaly, and Severe Thrombocytosis: A Case Report

Primary myelofibrosis (PMF) is a clonal disorder of a multipotent hematopoietic progenitor cell that occurs predominantly in the elderly age group. We report here an 11-year-old girl who presented with headache, fever, and splenomegaly. Full blood cell count revealed severe thrombocytosis. Laboratory and radiology examinations excluded the diagnosis of essential/reactive thrombocytosis. Bone marrow biopsy showed megakaryocytic hyperplasia, reticulin and collagen fibrosis, and erythroid and myeloid hypoplasia, findings compatible to PMF. The patient was put symptomatically on hydroxyurea and hydration due to thrombocytosis and platelet number decreased. Hematopoietic stem cell transplantation was scheduled to avoid delaying definitive therapy and secondary complications such as infections and transfusion dependency. To the best of our knowledge, this is the first reported case of PMF in childhood in Greece.

A Rare Case of Primary Myelofibrosis in a 14-Year-Old Patient With Congenital Asplenia

Primary myelofibrosis (PMF) is rarely diagnosed in children, and in most cases in children younger than 3 years old. Pediatric PMF generally follows a benign course and is usually managed supportively with blood transfusions and prophylactic antibiotics for infections. We present a case of a 17-year-old girl diagnosed with PMF at the age of 14 years. A computed tomography scan performed at the time of an appendectomy showed congenital asplenism. To our knowledge, this is only the third case of myelofibrosis and congenital asplenism to be reported in the literature. Whether asplenism contributed to the development of myelofibrosis is not known.

Transcriptome Analysis of Monozygotic Twin Brothers with Childhood Primary Myelofibrosis

Primary myelofibrosis (PMF) is a chronic myeloproliferative disorder in human bone marrow. Over 50% of patients with myelofibrosis have mutations in JAK2, MPL, or CALR. However, these mutations are rarely detected in children, suggesting a difference in the pathogenesis of childhood PMF. In this study, we investigated the response to drug treatment of a monozygotic twin pair with typical childhood PMF. The twin exhibited different clinical outcomes despite following the same treatment regimen. The transcriptomic profiles of patient samples after drug treatment (E2 and Y2) were significantly different between the twin pair, which is consistent with the observation that the drug treatment was effective only in the younger brother, despite the twin being genetically identical. Bioinformatics analysis of the drug-responsive genes showed that the JAK-STAT pathway was activated in the cured younger brother, which is opposite to the pathway inhibition observed in adult PMF cases following treatment. Moreover, apoptosis and cell cycle processes were both significantly influenced by drug treatment in the sample of younger brother (Y2), implying their potential association with the pathogenesis of childhood PMF. Gene mutations in JAK2, MPL, or CALR were not observed; however, mutations in genes including SRSF2 and SF3B1 occurred in this twin pair with childhood PMF. Gene fusion events were extensively screened in the twin pair samples and the occurrence of IGLV2-14-IGLL5 gene fusion was confirmed. The current study reported at transcriptomic level the different responses of monozygotic twin brothers with childhood PMF to the same androgen/prednisone treatment regimen providing new insights into the potential pathogenesis of childhood PMF for further research and clinical applications.