The etiology of hypereosinophilia is divided into 2 categories, clonal or reactive in origin. The clonal form typically presents as a chronic myeloproliferative neoplasm (MPN), associated with rearrangements involving PDGFRA/B, FGFR1 or with the PCM1-JAK2 fusion.1 These fusion genes result in a constitutively active tyrosine kinase, and the PDGFR-rearrangements are very sensitive to tyrosine kinase inhibitors (TKIs) such as imatinib. More rarely, these rearrangements can be seen in cases of acute myeloid leukemia (AML), T-cell lymphoblastic leukemia/lymphoma (T-ALL/T-LLy), or mixed phenotype acute leukemia (MPAL), generally associated with eosinophilia.1 Given the varied presentation, the World Health Organization now classifies these malignancies under the category of “myeloid/lymphoid neoplasms with eosinophilia (MLN-Eo) and rearrangement of PDGFRA, PDGFRB, or FGFR1, or with PCM1-JAK2”. This disease is extremely uncommon in children and only 8 FIP1L1-PDGRFA cases have previously been described.
by
Uma Athale;
Nobuko Hijiya;
Briana Patterson;
Daniel Bergsagel;
Jeffrey R. Andolina;
Henrique Bittencourt;
Kirk R. Schultz;
Michael J. Burke;
Michele S. Redell;
E. Anders Kolb;
Donna L. Johnston
Chronic myeloid leukemia (CML) accounts for 2-3% of leukemias in children under 15 and 9% in adolescents aged 15-19. The diagnosis and management of CML in children, adolescents, and young adults have several differences compared to that in adults. This review outlines the diagnosis and management of the underlying disease as well as challenges that can occur when dealing with CML in this patient population.
Hematogones are immature normal B cell precursors with a characteristic immunophenotype profile on flow cytometry that typically do not express surface immunoglobulin light chains. In this report, we describe a case in which the hematogones exhibit light chain restriction. Our patient was a 4-year-old boy with a complicated medical history involving treatment for a presumed bilateral Wilms tumor of the kidney that on later resection was diagnosed as Burkitt lymphoma. Flow cytometry analysis of his bone marrow revealed a small distinct population of cells expressing dim cluster of differentiation (CD)10, CD19, CD22, CD38, dim CD58, human leukocyte antigen-D related (HLA-DR), and dim CD45, which are characteristic of hematogones. These cells, however, demonstrated dim surface immunoglobulin lambda light-chain restriction. Molecular study results for immunoglobulin heavy and kappa light-chain gene rearrangements were negative. We present this case to raise awareness of the potential pitfalls of working up bone marrow for involvement by B cell lymphoproliferative disorder.