Myeloid neoplasms with eosinophilia

The Role of Imatinib in Pediatric Type 1 Diabetes

We report the first case of imatinib use in an adolescent with diabetes and suggest that it impacts the natural course of disease. A 14-year-old male patient presented in diabetic ketoacidosis (DKA) and was diagnosed with presumed autoantibody-negative type 1 diabetes (T1D) as well as myeloid neoplasm with platelet-derived growth factor receptor beta (PDGFRB) rearrangement. After starting exogenous insulin and imatinib, he experienced a 1.7-point reduction in glycated hemoglobin (HbA1c) and a 71% reduction in insulin requirement with sustained partial diabetes remission. Our case suggests imatinib as a potential therapeutic agent for pediatric T1D.

World Health Organization and International Consensus Classification of eosinophilic disorders: 2024 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of non-hematologic (secondary or reactive) and hematologic (primary or clonal) disorders with the potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 109/L, and may be associated with tissue damage. After the exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of various tests. They include morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, molecular testing and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2022 World Health Organization and International Consensus Classification endorse a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions" (MLN-eo-TK), and the MPN subtype, "chronic eosinophilic leukemia" (CEL). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., <1.5 × 109/L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Pemigatinib was recently approved for patients with relapsed or refractory FGFR1-rearranged neoplasms. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, is approved by the U.S Food and Drug Administration for patients with idiopathic HES. Cytotoxic chemotherapy agents, and hematopoietic stem cell transplantation have been used for aggressive forms of HES and CEL, with outcomes reported for limited numbers of patients. Targeted therapies such as the IL-5 receptor antibody benralizumab, IL-5 monoclonal antibody depemokimab, and various tyrosine kinase inhibitors for MLN-eo-TK, are under active investigation.

Cardiac Mechanics and Valvular and Vascular Abnormalities in Hypereosinophilic Syndrome

Hypereosinophilic syndrome (HES) is considered to be a rare myeloproliferative disease that is characterized by persistent eosinophilia with associated multiple-organ damage. The heart is often involved in HES, representing a major cause of morbidity and mortality. HES is a heterogeneous group of disorders; the majority of the cases are idiopathic. Summarizing the findings regarding myocardial, valvular, and vascular abnormalities in a series of patients with HES, most studies found normal left ventricular (LV) volumes with reduced LV global longitudinal strain and LV apical rotation and twist in HES cases, accompanied by increased left atrial (LA) volumes and stroke volumes, reduced peak LA circumferential strain (representing systolic abnormalities), and mitral annular dilation and functional deterioration. Regarding the right heart, preserved right ventricular volumes and functional properties, increased right atrial volumes, mild RA functional abnormalities, and dilated tricuspid annular dimensions without functional impairment could be seen in these studies. Aortic and pulmonary valves showed no specific disease-related alterations. Vascular abnormalities included increased aortic stiffness without dilation of the aorta and pulmonary hypertension in some cases. These results suggest disease-specific but relatively mild myocardial, valvular, and vascular abnormalities in HES. The present review aimed to summarize the available clinical data about cardiac mechanics and valvular and vascular abnormalities in a series of patients with HES.

Human germline gain-of-function in STAT6: from severe allergic disease to lymphoma and beyond

Signal transducer and activator of transcription (STAT)-6 is a transcription factor central to pro-allergic immune responses, although the function of human STAT6 at the whole-organism level has long remained unknown. Germline heterozygous gain-of-function (GOF) rare variants in STAT6 have been recently recognized to cause a broad and severe clinical phenotype of early-onset, multi-system allergic disease. Here, we provide an overview of the clinical presentation of STAT6-GOF disease, discussing how dysregulation of the STAT6 pathway causes severe allergic disease, and identifying possible targeted treatment approaches. Finally, we explore the mechanistic overlap between STAT6-GOF disease and other monogenic atopic disorders, and how this group of inborn errors of immunity (IEIs) powerfully inform our fundamental understanding of common human allergic disease.

Clonal Hematopoiesis, Inflammation, and Hematologic Malignancy

Somatic or acquired mutations are postzygotic genetic variations that can occur within any tissue. These mutations accumulate during aging and have classically been linked to malignant processes. Tremendous advancements over the past years have led to a deeper understanding of the role of somatic mutations in benign and malignant age-related diseases. Here, we review the somatic mutations that accumulate in the blood and their connection to disease states, with a particular focus on inflammatory diseases and myelodysplastic syndrome. We include a definition of clonal hematopoiesis (CH) and an overview of the origins and implications of these mutations. In addition, we emphasize somatic disorders with overlapping inflammation and hematologic disease beyond CH, including paroxysmal nocturnal hemoglobinuria and aplastic anemia, focusing on VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Finally, we provide a practical view of the implications of somatic mutations in clinical hematology, pathology, and beyond.

Hematological Neoplasms with Eosinophilia

Eosinophils in peripheral blood account for 0.3-5% of leukocytes, which is equivalent to 0.05-0.5 × 109/L. A count above 0.5 × 109/L is considered to indicate eosinophilia, while a count equal to or above 1.5 × 109/L is defined as hypereosinophilia. In bone marrow aspirate, eosinophilia is considered when eosinophils make up more than 6% of the total nuclear cells. In daily clinical practice, the most common causes of reactive eosinophilia are non-hematologic, whether they are non-neoplastic (allergic diseases, drugs, infections, or immunological diseases) or neoplastic (solid tumors). Eosinophilia that is associated with a hematological malignancy may be reactive or secondary to the production of eosinophilopoietic cytokines, and this is mainly seen in lymphoid neoplasms (Hodgkin lymphoma, mature T-cell neoplasms, lymphocytic variant of hypereosinophilic syndrome, and B-acute lymphoblastic leukemia/lymphoma). Eosinophilia that is associated with a hematological malignancy may also be neoplastic or primary, derived from the malignant clone, usually in myeloid neoplasms or with its origin in stem cells (myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions, acute myeloid leukemia with core binding factor translocations, mastocytosis, myeloproliferative neoplasms, myelodysplastic/myeloproliferative neoplasms, and myelodysplastic neoplasms). There are no concrete data in standardized cytological and cytometric procedures that could predict whether eosinophilia is reactive or clonal. The verification is usually indirect, based on the categorization of the accompanying hematologic malignancy. This review focuses on the broad differential diagnosis of hematological malignancies with eosinophilia.

Durable response from fibroblast growth factor receptor inhibition in intrahepatic cholangiocarcinoma terminated by metachronous acute myeloid leukemia: a case report

INTRODUCTION

Advances in the treatment of biliary tract cancer have been made possible through gains in genomic and epigenetic tumor understanding. The use of fibroblast growth factor receptor inhibitor has enabled significant clinical improvement in a specific group of patients with intrahepatic cholangiocarcinoma, some of whom with very durable responses.

CASE PRESENTATION

We present the case of a 69-year-old Caucasian patient with advanced intrahepatic cholangiocarcinoma who received the therapy with selective oral inhibitor of fibroblast growth factor receptor 1, 2, and 3 pemigatinib after multiple previous chemotherapies. This resulted in a durable stable disease condition for 15 months with good tolerability. The diagnosis of acute myeloid leukemia was an unanticipated serious adverse event, in which the impact of fibroblast growth factor receptor inhibition could not yet be determined due to inadequate data.

CONCLUSIONS

It is still possible to achieve durable tumor response in advanced previously treated intrahepatic cholangiocarcinoma through targeted therapies. The prolonged progression free survival means that there could be an increased risk of secondary malignancy in this patient group, which necessitates diagnostic and therapeutic strategies.

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase fusion genes: A workshop report with focus on novel entities and a literature review including paediatric cases

Myeloid/lymphoid neoplasms with eosinophilia (M/LN-eo) and tyrosine kinase (TK) gene fusions are a rare group of haematopoietic neoplasms with a broad range of clinical and morphological presentations. Paediatric cases have increasingly been recognised. Importantly, not all appear as a chronic myeloid neoplasm and eosinophilia is not always present. In addition, standard cytogenetic and molecular methods may not be sufficient to diagnose M/LN-eo due to cytogenetically cryptic aberrations. Therefore, additional evaluation with fluorescence in-situ hybridisation and other molecular genetic techniques (array-based comparative genomic hybridisation, RNA sequencing) are recommended for the identification of specific TK gene fusions. M/LN-eo with JAK2 and FLT3-rearrangements and ETV6::ABL1 fusion were recently added as a formal member to this category in the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In addition, other less common defined genetic alterations involving TK genes have been described. This study is an update on M/LN-eo with TK gene fusions with focus on novel entities, as illustrated by cases submitted to the Bone Marrow Workshop, organised by the European Bone Marrow Working Group (EBMWG) within the frame of the 21st European Association for Haematopathology congress (EAHP-SH) in Florence 2022. A literature review was performed including paediatric cases of M/LN-eo with TK gene fusions.

Clinical Validation of FusionPlex RNA Sequencing and Its Utility in the Diagnosis and Classification of Hematologic Neoplasms

Recurrent gene rearrangements result in gene fusions that encode chimeric proteins, driving the pathogenesis of many hematologic neoplasms. The fifth edition World Health Organization classification and International Consensus Classification 2022 include an expanding list of entities defined by such gene rearrangements. Therefore, sensitive and rapid methods are needed to identify a broad range of gene fusions for precise diagnosis and prognostication. In this study, we validated the FusionPlex Pan-Heme panel analysis using anchored multiplex PCR/targeted RNA next-generation sequencing for routine clinical testing. Furthermore, we assessed its utility in detecting gene fusions in myeloid and lymphoid neoplasms. The validation cohort of 61 cases demonstrated good concordance between the FusionPlex Pan-Heme panel and other methods, including chromosome analysis, fluorescence in situ hybridization, RT-PCR, and Sanger sequencing, with an analytic sensitivity and specificity of 95% and 100%, respectively. In an independent cohort of 28 patients indicated for FusionPlex testing, gene fusions were detected in 21 patients. The FusionPlex Pan-Heme panel analysis reliably detected fusion partners and patient-specific fusion sequences, allowing accurate classification of hematologic neoplasms and the discovery of new fusion partners, contributing to a better understanding of the pathogenesis of the diseases.

Myeloid/Lymphoid Neoplasms with ETV6::PDGFRB Fusion Gene: A Rare Case of Poor Response to Imatinib and Possible Transformation Mechanisms from Myeloid Neoplasms of Bone Marrow to T-Cell Lymphoblastic Lymphoma Invasion in Lymph Nodes

The ETV6::PDGFRB fusion gene is commonly reported in chronic myelomonocytic leukemia with eosinophilia, yet patients with ETV6::PDGFRB presenting myeloid and lymphoid neoplasms successively have not been reported. Here, we report the first case of a 35-year-old man with myeloid and lymphoid neoplasms harboring an ETV6::PDGFRB fusion gene who demonstrated poor response to imatinib. The patient was diagnosed with an ETV6::PDGFRB fusion gene myeloid neoplasm on initial diagnosis at our hospital. After 5 months of treatment with imatinib, he was diagnosed with T-cell lymphoblastic lymphoma. ETV6::PDGFRB turned negative after increasing the dose of imatinib, but enlarged superficial lymph nodes reappeared the following year. Notably, the patient exhibited a worse response to imatinib treatment. This study describes this rare case and speculates on a possible mechanism.

Population pharmacokinetic and exposure-response analyses of pemigatinib in patients with advanced solid tumors including cholangiocarcinoma

Pemigatinib is a selective, potent, oral inhibitor of fibroblast growth factor receptor (FGFR)1-3 with efficacy in patients with previously treated, advanced/metastatic cholangiocarcinoma (CCA) with FGFR2 alterations. A previously developed population pharmacokinetic (PK) model of pemigatinib was refined using an updated dataset with 467 participants from seven clinical studies, including patients with CCA. Updated PK model parameters were used to evaluate the association between pemigatinib exposure and efficacy and safety. Pemigatinib PK was adequately described by a two-compartment model with linear elimination and sequential zero- and first-order absorption. The final model successfully minimized, had a successful covariance step, and showed unbiased goodness-of-fit. Estimated first-order absorption rate constant and apparent clearance were 3.7/h and 10.7 L/h, respectively. Sex, baseline body weight, and concomitant use of phosphate binders, proton pump inhibitors, or histamine-2 antagonists significantly impacted PK parameters; however, the impact of covariates on PK exposure was not clinically significant. Steady-state pemigatinib exposure and mean change from baseline in serum phosphate concentration were associated with objective response rate in a bell-shaped relationship and were significantly associated with increased hyperphosphatemia. Pemigatinib exposure was associated with treatment-emergent adverse events, such as decreased appetite, nausea, and stomatitis, although the relationships were shallow. Overall, analyses indicate that 13.5 mg pemigatinib once daily in 21-day cycles (2 weeks on, 1 week off) offers a favorable benefit-risk profile in patients with advanced/metastatic or surgically unresectable CCA and is the optimal dose for clinical development.

Gene Therapy for Immunoglobulin E, Complement-Mediated, and Eosinophilic Disorders

Immunoglobulin E, complement, and eosinophils play an important role in host defense, but dysfunction of each of these components can lead to a variety of human disorders. In this review, we summarize how investigators have adapted gene therapy and antisense technology to modulate immunoglobulin E, complement, and/or eosinophil levels to treat these disorders.

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions: reevaluation of the defining characteristics in a registry-based cohort

In a registry-based analysis of 135 patients with "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions" (MLN-TK; FIP1L1::PDGFRA, n = 78; PDGFRB, diverse fusions, n = 26; FGFR1, diverse, n = 9; JAK2, diverse, n = 11; ETV6::ABL1, n = 11), we sought to evaluate the disease-defining characteristics. In 81/135 (60%) evaluable patients, hypereosinophilia (>1.5 × 109/l) was observed in 40/44 (91%) FIP1L1::PDGFRA and 7/7 (100%) ETV6::ABL1 positive patients but only in 13/30 (43%) patients with PDGFRB, FGFR1, and JAK2 fusion genes while 9/30 (30%) patients had no eosinophilia. Monocytosis >1 × 109/l was identified in 27/81 (33%) patients, most frequently in association with hypereosinophilia (23/27, 85%). Overall, a blast phase (BP) was diagnosed in 38/135 (28%) patients (myeloid, 61%; lymphoid, 39%), which was at extramedullary sites in 18 (47%) patients. The comparison between patients with PDGFRA/PDGFRB vs. FGFR1, JAK2, and ETV6::ABL1 fusion genes revealed a similar occurrence of primary BP (17/104, 16% vs. 8/31 26%, p = 0.32), a lower frequency (5/87, 6% vs. 8/23, 35%, p = 0.003) of and a later progression (median 87 vs. 19 months, p = 0.053) into secondary BP, and a better overall survival from diagnosis of BP (17.1 vs. 1.7 years, p < 0.0008). We conclude that hypereosinophilia with or without monocytosis and various phenotypes of BP occur at variable frequencies in MLN-TK.

Systemic mastocytosis in adults: 2023 update on diagnosis, risk stratification and management

OVERVIEW

Systemic mastocytosis (SM) results from clonal proliferation of mast cells (MC) in extracutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal MC clusters in the bone marrow and/or extracutaneous organs. Minor diagnostic criteria include elevated serum tryptase level, MC CD25/CD2/CD30 expression, and presence of activating KIT mutations.

RISK STRATIFICATION

Establishing SM subtype as per the International Consensus Classification/World Health Organization classification systems is an important first step. Patients either have indolent/smoldering SM (ISM/SSM) or advanced SM, including aggressive SM (ASM), SM with associated myeloid neoplasm (SM-AMN), and mast cell leukemia. Identification of poor-risk mutations (i.e., ASXL1, RUNX1, SRSF2, NRAS) further refines the risk stratification. Several risk models are available to help assign prognosis in SM patients.

MANAGEMENT

Treatment goals for ISM patients are primarily directed toward anaphylaxis prevention/symptom control/osteoporosis treatment. Patients with advanced SM frequently need MC cytoreductive therapy to reverse disease-related organ dysfunction. Tyrosine kinase inhibitors (TKI) (midostaurin, avapritinib) have changed the treatment landscape in SM. While deep biochemical, histological and molecular responses have been documented with avapritinib treatment, its efficacy as monotherapy against a multimutated AMN disease component in SM-AMN patients remains unclear. Cladribine continues to have a role for MC debulking, whereas interferon-α has a diminishing role in the TKI era. Treatment of SM-AMN primarily targets the AMN component, particularly if an aggressive disease such as acute leukemia is present. Allogeneic stem cell transplant has a role in such patients. Imatinib has a therapeutic role only in the rare patient with an imatinib-sensitive KIT mutation.

HES and EGPA: Two Sides of the Same Coin

Elevated eosinophil counts are implicated in multiple diseases, from relatively prevalent organ-specific disorders such as severe eosinophilic asthma, to rare multisystem disorders such as hypereosinophilic syndrome (HES) and eosinophilic granulomatosis with polyangiitis (EGPA). Patients with these multisystem diseases, often associated with markedly elevated eosinophil counts, have a substantial risk of morbidity and mortality due to delayed diagnosis or inadequate treatment. A thorough workup of symptomatic patients presenting with elevated eosinophil counts is essential, although in some cases the differential diagnosis may remain difficult because of overlapping presentations between HES and EGPA. Notably, first- and second-line treatment options and response to therapy may differ for specific HES and EGPA variants. Oral corticosteroids are the first line of treatment for HES and EGPA, except when HES is the result of specific mutations driving clonal eosinophilia that are amenable to targeted treatment with a kinase inhibitor. Cytotoxic or immunomodulatory agents may be required for those with severe disease. Novel eosinophil-depleting therapies, such as those targeting interleukin 5 or its receptor, have shown great promise in reducing blood eosinophil counts, and reducing disease flares and relapses in patients with HES and EGPA. Such therapies could reduce the side effects associated with long-term oral corticosteroids or immunosuppressant use. This review provides a pragmatic guide to approaching the diagnosis and clinical management of patients with systemic hypereosinophilic disorders. We highlight practical considerations for clinicians and present cases from real-world clinical practice to show the complexity and challenges associated with diagnosing and treating patients with HES and EGPA.

False-Negative Testing for FIP1L1::PDGFRA by Fluorescence in situ Hybridization Is a Frequent Cause of Diagnostic Delay

The imatinib-sensitive fusion gene FIP1L1::PDGFRA is the most frequent molecular abnormality identified in patients with eosinophilic myeloid neoplasms. Rapid recognition of this mutation is essential given the poor prognosis of PDGFRA-associated myeloid neoplasms prior to the availability of imatinib therapy. We report a case of a patient in whom delayed diagnosis resulted in cardiac transplantation for eosinophilic endomyocardial fibrosis. The delay in diagnosis was due, in part, to a false-negative result in fluorescence in situ hybridization (FISH) testing for FIP1L1::PDGFRA. To explore this further, we examined our cohort of patients presenting with confirmed or suspected eosinophilic myeloid neoplasms and found 8 additional patients with negative FISH results despite a positive reverse-transcriptase polymerase chain reaction test for FIP1L1::PDGFRA. More importantly, false-negative FISH results delayed the median time to imatinib treatment by 257 days. These data emphasize the importance of empiric imatinib therapy in patients with clinical features suggestive of PDGFRA-associated disease.

The multidisciplinary approach to eosinophilia

Eosinophilic granulocytes are normally present in low numbers in the bloodstream. Patients with an increased number of eosinophilic granulocytes in the differential count (eosinophilia) are common and can pose a clinical challenge because conditions with eosinophilia occur in all medical specialties. The diagnostic approach must be guided by a thorough medical history, supported by specific tests to guide individualized treatment. Neoplastic (primary) eosinophilia is identified by one of several unique acquired genetic causes. In contrast, reactive (secondary) eosinophilia is associated with a cytokine stimulus in a specific disease, while idiopathic eosinophilia is a diagnosis by exclusion. Rational treatment is disease-directed in secondary cases and has paved the way for targeted treatment against the driver in primary eosinophilia, whereas idiopathic cases are treated as needed by principles in eosinophilia originating from clonal drivers. The vast majority of patients are diagnosed with secondary eosinophilia and are managed by the relevant specialty-e.g., rheumatology, allergy, dermatology, gastroenterology, pulmonary medicine, hematology, or infectious disease. The overlap in symptoms and the risk of irreversible organ involvement in eosinophilia, irrespective of the cause, warrants that patients without a diagnostic clarification or who do not respond to adequate treatment should be referred to a multidisciplinary function anchored in a hematology department for evaluation. This review presents the pathophysiology, manifestations, differential diagnosis, diagnostic workup, and management of (adult) patients with eosinophilia. The purpose is to place eosinophilia in a clinical context, and therefore justify and inspire the establishment of a multidisciplinary team of experts from diagnostic and clinical specialties at the regional level to support the second opinion. The target patient population requires highly specialized laboratory analysis and therapy and occasionally has severe eosinophil-induced organ dysfunction. An added value of a centralized, clinical function is to serve as a platform for education and research to further improve the management of patients with eosinophilia. Primary and idiopathic eosinophilia are key topics in the review, which also address current research and discusses outstanding issues in the field.

French guidelines for the etiological workup of eosinophilia and the management of hypereosinophilic syndromes

Eosinophilic-related clinical manifestations are protean and the underlying conditions underpinning eosinophilia are highly diverse. The etiological workup of unexplained eosinophilia/hypereosinophilia can be challenging, and can lead sometimes to extensive, inappropriate, costly and/or invasive investigations. To date, guidelines for the etiological workup and management of eosinophilia are mainly issued by hematologists, and thus mostly cover the scope of clonal hypereosinophilic syndromes (HES). Here, thanks to an extensive literature review, and thanks to the joint work of a large panel of experts involving physicians from both adult and pediatric medicine and from various subspecialties (as well as a representative of a patients' association representative), we provide recommendations for both the step-by step diagnostic workup of eosinophilia (whether unexplained or within specific contexts) as well as the management and follow-up of the full spectrum of eosinophilic disorders (including clonal, reactive, lymphocytic and idiopathic HES, as well as single-organ diseases). Didactic prescription summaries intended to facilitate the prescription of eosinophil-targeted drugs are also provided, as are practical diagnostic and therapeutic algorithms. Lastly, this set of recommendations also includes a summary intended for general practitioners, as well as an overview of the therapeutic patient education program set up by the French reference center for HES. Further updates will be mandatory as new validated information emerges.

Rare and potentially fatal - Cytogenetically cryptic TNIP1::PDGFRB and PCM1::FGFR1 fusion leading to myeloid/lymphoid neoplasms with eosinophilia in children

Myeloid/lymphoid neoplasms with eosinophilia (MLN-eos) are rare haematological neoplasms primarily affecting adults. The heterogeneous clinical picture and the rarity of the disease, especially in children, may delay an early diagnosis. MLN-eos are characterized by constitutive tyrosine kinase (TK) activity due to gene fusions. It is thus of importance to obtain a prompt genetic diagnosis to start a specific therapy. Here, we outline the clinical, genetic, and biochemical background of TK driven MLN-eos and report two extremely rare paediatric cases of MLN-eo, the used diagnostic methods, therapy and clinical outcomes. Our results demonstrate that, standard cytogenetic and molecular methods may not be sufficient to diagnose MLN-eo due to cytogenetically cryptic aberrations. We therefore recommend performing additional evaluation with fluorescence in-situ hybridization and molecular genetic methods (array-based comparative genomic hybridization and RNA sequencing) which will lead to the correct diagnosis. Following this diagnostic route we detected a TNIP1::PDGFRB and a PCM1::FGFR1 fusion in our patients. Thus, genetic diagnosis must be precise and quick in order to initiate adequate therapies with tyrosine kinase inhibitors or HSCT.

Pemigatinib for the treatment of myeloid/lymphoid neoplasms with FGFR1 rearrangement

INTRODUCTION

Myeloid/lymphoid neoplasms with fibroblast growth factor receptor-1 (FGFR1) rearrangements (MLN^FGFR1) are rare entities with aggressive features and poor prognosis. Presentation is heterogeneous, ranging from myeloproliferative neoplasms (with or without eosinophilia) to T-cell lymphoma and acute leukemia. Historical treatments have been guided by the presenting phenotype with induction chemotherapy frequently used. Pemigatinib is a FGFR1-3 tyrosine kinase inhibitor that has demonstrated high complete hematologic and cytogenetic response rates in MLN^FGFR1.

AREAS COVERED

We discuss the pathogenesis, presentation, and historical treatments for MLN^FGFR1, in addition to clinical data using pemigatinib and other targeted therapies. Discussion of the mechanism of action and adverse events are also included.

EXPERT OPINION

Pemigatinib represents a significant advance in the management of MLN^FGFR1. High rates of complete hematologic and cytogenetic response have been observed. While direct comparative data are unavailable, outcomes appear favorable compared to conventional approaches. Long term efficacy and tolerability are not yet known, and allogeneic hematopoietic stem cell transplant (alloHSCT) has been and continues to be the treatment with the highest chance of long term disease free survival in responding patients. Combinations of pemigatinib and chemotherapy, particularly for more aggressive phenotypes, warrant future investigation as does the use of pemigatinib maintenance following alloHSCT.

Role of Vitamin D in the diagnosis of acute Myeloid Leukemia

A range of hematological and biochemical markers have been investigated in Acute Myeloid Leukemia (AML) patients to determine the relationship between cancer growth and metabolic problems. This study aimed to determine the effects of vitamin D deficiency in Iraqi patients with acute myeloid leukemia who had recently been diagnosed. There was a significant inverse correlation between the total serum cholesterol (TC) level of acute myeloid leukemia (AML) patients group [(148.77±12.2) for males, (165.29±9.64) for females] and the control group [(164.50±7.26) for males, (180.05±7.31) for females], also an inverse correlation between high-density lipoprotein (HDL) level of acute myeloid leukemia (AML) patients group [(46.00±2.04) for males, (46.18±1.08) for females] and control group [(54.25±1.86) for males,(51.94±1.37) for females]. A significant difference was between the serum triglyceride (TG) level of acute myeloid leukemia (AML) patients group [(128.71±13.07) for males, (152.48±10.6) for females] and control group [85.12±11.30) for male, (90.50±10.90) for females], also between vitamin D level of acute myeloid leukemia (AML) patients group [(17.23±1.18) for males, (12.96±0.74) for females] and control group [(42.62±1.43) for males, (40.76±0.82) for females]. A statistically significant difference was between the serum calcium levels of individuals with acute myeloid leukemia [(8.99±0.32) for males, (8.91±0.23) for females] and the control group [(13.13±1.16) for males, (10.73±0.28) for females]. AML patients can benefit from vitamin D treatment, according to a pairwise analysis of receiver operating characteristic (ROC) curves. The above results are related to concluding that Vitamin D can be utilized as a diagnostic test for AML patients. Keywords; acute myeloid leukemia (AML), Hypereosinophilia, ROC curve, hypocholesterolemia, vitamin D.

Clinical Response to Upfront Targeted Tyrosine Kinase Inhibitors among Patients with Myeloid/Lymphoid Neoplasms with Eosinophilia and Tyrosine Kinase Gene Fusion

INTRODUCTION

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusion (MLN-TK) is an entity encompassed of a heterogeneous group of rare hematopoietic neoplasms that are driven by gene fusion involving PDGDRA/B, FGFR1, JAK2, FLT3 or ETV6::ABL1. Though patients presenting with chronic phase MLN-TK with PDGFRA fusion display a favorable outcome in response to upfront TK inhibitor (TKI) therapy, the outcomes of MLNs driven by other TK fusions are not well described. In this study, we aimed to critically analyze the treatment outcomes of patients with MLN-TK, focusing on the role of upfront TKIs in both chronic- and blast-phase diseases.

METHODS

The retrospective study included patients with confirmed MLN-TK from 3 centers and assessed demographic and clinical variables, treatment, and outcomes.

RESULTS

Forty-two patients with confirmed MLN-TK [PDGFRA (n = 22), PDGFRB (n = 4), FGFR1(n = 10), JAK2 (n = 2); and FLT3 (n = 3)] were included. Fifteen of 25 (60%) chronic-phased patients received upfront TKI therapy had a long-term remission. Nine of 16 (60%) blast-phase patients with upfront TKIs also achieved complete remission and remained alive at a median follow-up of 20 months. All 3 patients with blast phase disease who received upfront chemotherapy without positive response did not respond to subsequent TKI therapy, emphasizing the importance of initiating TKI therapy early. Upfront TKI therapy was associated with longer overall survival in univariate analyses (HR, 0.054 [95% CI, 0.007-0.42]) and multivariate analyses (HR, 0.03 [95% CI, 0.002-0.47]).

CONCLUSION

The outcomes of upfront TKI therapy are excellent for MLN-TK in both chronic and blast phases, regardless of gene abnormalities.

Myeloid and lymphoid neoplasm with novel complex translocation: unusual case report with T-lymphoblastic lymphoma, myeloid hyperplasia, eosinophilia, basophilia, and t(1;8;10)( (p31;q24;q11.2)

Myeloid and lymphoid neoplasms with eosinophilia (M/Ls-Eo) encompass heterogeneous but aggressive hematopoietic disorders triggered by fusion genes or mutations that typically lead to constitutive overexpression of tyrosine kinase. The occurrence of T-lymphoblastic lymphoma in the setting of M/Ls-Eo has been reported rarely in the literature. Herein, we present an unusual case of a 28-year-old male patient who presented with massive lymphadenopathy and T-lymphoblastic lymphoma in the lymph node occurring concurrently with myeloid hyperplasia, eosinophilia and basophilia in peripheral blood and bone marrow biopsy. The syndrome was associated with a novel complex karyotype involving der(8)t(1;8;10)(p31;q24;q11.2). The FISH study was negative for BCR::ABL1, JAK2, PDGFRA, PDGFRB, and FGFR1 rearrangements. The patient's clinical course was aggressive and resistant to multiple lines of intensive chemotherapy regimens. Therefore, he underwent allogenic stem cell transplantation with a fully matched donor. A brief review of the occurrence of T-LBL in conjunction with M/Ls-Eo neoplasm was made with a special focus on molecular aspects.

Updates on eosinophilic disorders

This review addresses changes and updates in eosinophilic disorders under the International Consensus Classification (ICC). The previous category of myeloid/lymphoid neoplasm with eosinophilia (M/LN-eo) and a specific gene rearrangement is changed to M/LN-eo with tyrosine kinase gene fusions to reflect the underlying genetic lesions. Two new members, M/LN-eo with ETV6::ABL1 fusion and M/LN-eo with various FLT3 fusions, have been added to the category; and M/LN-eo with PCM1::JAK2 and its genetic variants ETV6::JAK2 and BCR::JAK2 are recognized as a formal entity from their former provisional status. The updated understanding of the clinical and molecular genetic features of PDGFRA, PDGFRB and FGFR1 neoplasms is summarized. Clear guidance as to how to distinguish these fusion gene-associated disorders from the overlapping entities of Ph-like B-acute lymphoblastic leukemia (ALL), de novo T-ALL, and systemic mastocytosis is provided. Bone marrow morphology now constitutes one of the diagnostic criteria of chronic eosinophilic leukemia, NOS (CEL, NOS), and idiopathic hypereosinophilia/hypereosinophilic syndrome (HE/HES), facilitating the separation of a true myeloid neoplasm with characteristic eosinophilic proliferation from those of unknown etiology and not attributable to a myeloid neoplasm.

Proposed refined diagnostic criteria and classification of eosinophil disorders and related syndromes

Eosinophilia and eosinophil activation are recurrent features in various reactive states and certain hematologic malignancies. In patients with hypereosinophilia (HE), HE-induced organ damage is often encountered and may lead to the diagnosis of a hypereosinophilic syndrome (HES). A number of known mechanisms and etiologies contribute to the development of HE and HES. Based on these etiologies and the origin of eosinophils, HE and HES are divided into primary forms where eosinophils are clonal cells, reactive forms where an underlying reactive or neoplastic condition is detected and eosinophils are considered to be "non-clonal" cells, and idiopathic HE and HES in which neither a clonal nor a reactive underlying pathology is detected. Since 2012, this classification and the related criteria have been widely accepted and regarded as standard. However, during the past few years, new developments in the field and an increasing number of markers and targets have created a need to update these criteria and the classification of HE and HES. To address this challenge, a Working Conference on eosinophil disorders was organized in 2021. In this conference, a panel of experts representing the relevant fields, including allergy, dermatology, hematology, immunology, laboratory medicine, and pathology, met and discussed new markers and concepts as well as refinements in definitions, criteria and classifications of HE and HES. The outcomes of this conference are presented in this article and should assist in the diagnosis and management of patients with HE and HES in daily practice and in the preparation and conduct of clinical trials.

Available and emerging therapies for bona fide advanced systemic mastocytosis and primary eosinophilic neoplasms

The historically poor prognosis of patients with advanced systemic mastocytosis (AdvSM) and primary eosinophilic neoplasms has shifted to increasingly favorable outcomes with the discovery of druggable targets. The multikinase/KIT inhibitor midostaurin and the highly selective KIT D816V inhibitor avapritinib can elicit marked improvements in measures of mast cell (MC) burden as well as reversion of MC-mediated organ damage (C-findings) and disease symptoms. With avapritinib, the achievement of molecular remission of KIT D816V and improved survival compared with historical therapy suggests a potential to affect disease natural history. BLU-263 and bezuclastinib are KIT D816V inhibitors currently being tested in trials of AdvSM. In the new World Health Organization and International Consensus Classifications, the category of "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase (TK) gene fusions" is inclusive of rearrangements involving PDGFRA, PDGFRB, FGFR1, JAK2, FLT3, and ETV6::ABL1. While the successful outcomes with imatinib in FIP1L1::PDGFRA-positive cases and PDGFRB-rearranged neoplasms have become the "poster children" of these disorders, the responses of the other TK-driven neoplasms to small-molecule inhibitors are more variable. The selective FGFR inhibitor pemigatinib, approved in August 2022, is a promising therapy in aggressive FGFR1-driven diseases and highlights the role of such agents in bridging patients to allogeneic transplantation. This review summarizes the data for these approved and investigational agents and discusses open questions and future priorities regarding the management of these rare diseases.

Molecular-Targeted Therapy for Tumor-Agnostic Mutations in Acute Myeloid Leukemia

Comprehensive genomic profiling examinations (CGPs) have recently been developed, and a variety of tumor-agnostic mutations have been detected, leading to the development of new molecular-targetable therapies across solid tumors. In addition, the elucidation of hereditary tumors, such as breast and ovarian cancer, has pioneered a new age marked by the development of new treatments and lifetime management strategies required for patients with potential or presented hereditary cancers. In acute myeloid leukemia (AML), however, few tumor-agnostic or hereditary mutations have been the focus of investigation, with associated molecular-targeted therapies remaining poorly developed. We focused on representative tumor-agnostic mutations such as the TP53, KIT, KRAS, BRCA1, ATM, JAK2, NTRK3, FGFR3 and EGFR genes, referring to a CGP study conducted in Japan, and we considered the possibility of developing molecular-targeted therapies for AML with tumor-agnostic mutations. We summarized the frequency, the prognosis, the structure and the function of these mutations as well as the current treatment strategies in solid tumors, revealed the genetical relationships between solid tumors and AML and developed tumor-agnostic molecular-targeted therapies and lifetime management strategies in AML.

Two pediatric oncologic cases of hypereosinophilic syndrome and review of the literature

BACKGROUND

Persistent peripheral blood hypereosinophilia may cause tissue damage, leading to hypereosinophilic syndrome (HES) with end-organ dysfunction. Here we discuss two unique pediatric cases of primary hypereosinophilic syndrome with oncologic etiologies to highlight the importance of early recognition, workup and treatment of HES. CASE 1: A previously healthy 7-year-old male presented with acute myocardial infarction and transient ischemic attack and found to have significant hyperleukocytosis with a total white blood count of 131 000 and hypereosinophilia with an absolute eosinophil count of 99 560. He was ultimately diagnosed with precursor B-cell acute lymphoblastic leukemia with immunoglobulin heavy chain gene rearrangement. He completed standard treatment without significant complications and remains in remission at about 2 years off therapy. He is in overall good health and has normal cardiac function. CASE 2: A 13-year-old female was referred for iron deficiency and reported a history of severe anxiety, shortness of breath and anorexia. She had experienced fatigue and dizziness associated with frequent panic attacks and shortness of breath with strenuous activity since the age of five. Serial laboratory investigations revealed persistent hypereosinophilia (AEC 4000-6000/μl). Additional workup revealed elevated vitamin B12 (>2000 pg/ml; normal range: 243-894) and tryptase (16.4 ng/ml; normal range: ≤10.9). The FIP1L1-PDGFRA gene fusion was detected by fluorescence in situ hybridization (FISH) on peripheral blood, diagnostic for myeloid/lymphoid neoplasm with eosinophilia. Evaluation for end-organ damage associated with persistent hypereosinophilia included an echocardiogram which revealed severe restrictive cardiomyopathy with pulmonary hypertension. Monotherapy with imatinib was initiated, after which she achieved a rapid hematologic response and remains in molecular remission, though she continues to have persistent asymptomatic severe pulmonary hypertension in the setting of severe diastolic dysfunction.

CONCLUSION

Persistent hyperosinophilia can be a silent cause of significant and often irreversible tissue damage and should therefore always prompt workup for both primary and secondary causes.

International Consensus Classification of Myeloid Neoplasms and Acute Leukemias: integrating morphologic, clinical, and genomic data

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

A diagnostic score for eosinophilic granulomatosis with polyangiitis among eosinophilic disorders

BACKGROUND

Eosinophilic granulomatosis with polyangiitis (EGPA) is a form of systemic vasculitis with eosinophilic inflammation. However, existing classification criteria are all designed to classify EGPA among vasculitis and there is no established method distinguishing EGPA from other eosinophilic disorders. The aim of the present study was to propose a scoring system to differentiate EGPA among eosinophilic disorders.

METHODS

Non-supervised hierarchical clustering using Ward's method and principal component analysis (PCA) were performed for 19 clinical parameters of 58 patients with eosinophilia-related diseases at a tertiary university hospital. The newly proposed scoring system was externally validated in 40 patients at another tertiary institution.

RESULTS

Two distinct clusters were identified, and clinical features including peripheral neuropathy, asthma, skin involvement, lung involvement, rheumatoid factor (RF) positivity, myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA) positivity, IgE elevation, C-reactive protein (CRP) elevation, and vasculitis pathological findings were predominantly observed in one of these clusters (p < 0.05). Ten features defining the cluster with a high rate of vasculitis were weighted by PCA to create the E-CASE (EGPA classification among systemic eosinophilia) scoring system, on a 16-point scale. Based on the distribution of scores in the primary cohort, we defined an E-CASE score ≥12 as positive, ≤ 8 as negative, and 9-11 as undeterminable. The sensitivity and specificity of the E-CASE score in the validation cohort were 93.3% and 100%, respectively.

CONCLUSIONS

We developed and verified a novel scoring system for differentiating EGPA from other types of eosinophilic disorders.

Eosinophilic Otitis Media: Modern Aspects of Pathogenesis, Clinical Features, Diagnosis and Treatment

Eosinophilic otitis media (EOM) is an inflammatory chronic disease of the middle ear, characterized by the presence of a particularly viscous effusion with a high content of protein toxins of eosinophilic origin in the middle ear cavity. The pathology has relationship with bronchial asthma, allergic rhinitis and chronic rhinosinusitis with nasal polyps. EOM is characterized by a sluggish course, a tendency to relapse, which can lead to a gradual hearing decrease up to complete deafness. In this paper, we reviewed the international literature with special attention to pathogenesis and treatment management.

Diagnosis and Management of Atypical Chronic Myeloid Leukemia with a t(2;13)(q33;q12) Translocation

Atypical chronic myeloid leukemia (aCML) is a rare myeloproliferative disorder that shares clinical features with chronic myeloid leukemia but lacks the classic t(9;22) BCR-ABL1 translocation and features prominent dysgranulopoiesis and granulocytic dysplasia. Challenges of this diagnosis include clinical and biologic heterogeneity, the high risk of transformation to acute myeloid leukemia, and the lack of standard treatment options. Allogeneic hematopoietic stem cell transplant is likely the preferred treatment, but this can be limited by patient psychosocial support, age, concomitant medical conditions, and availability of an appropriate donor. We report the case of a 61-year-old male with no significant past medical history diagnosed with aCML with a rare t(2;13)(q33;q12). He presented with weight loss, night sweats, splenomegaly, hyperleukocytosis, a leukoerythroblastic differential with a predominant neutrophilia, anemia, and thrombocytopenia. Subsequent peripheral blood and bone marrow studies lead to the diagnosis of aCML. He was recommended to undergo an allogeneic stem cell transplant evaluation and declined. He was initially treated with hydroxyurea and imatinib to which he responded for approximately three years. After clinical progression, he was treated with sorafenib, a multiprotein kinase inhibitor more commonly used in the treatment of hepatocellular and renal cell carcinoma due to its off target FLT3 inhibition. The patient achieved complete hematologic response which has been sustained for 7 years with tolerable side effects.

Myeloproliferative Syndrome With Eosinophilia Associated With Translocation t(8; 13) and T-cell Lymphoblastic Lymphoma: A Case Report and Review of the Literature

The 8p11 myeloproliferative syndrome (EMS) is an aggressive neoplasm associated with chromosomal translocations involving the fibroblast growth factor receptor 1 tyrosine kinase gene on chromosome 8p11. We report the case of a 31-year-old man with no prior medical history who presents with two weeks of sore throat and cervical lymphadenopathy up to 5 cm. Initial peripheral blood examination showed leukocytosis with predominantly neutrophils and eosinophilia. A CT scan demonstrated mediastinal lymphadenopathies, liver enlargement and splenomegaly. An excisional biopsy of a cervical lymph node demonstrated findings consistent with a diagnosis of T-cell lymphoblastic lymphoma. Bone marrow aspirate and biopsy revealed hypercellular marrow with granulocytic predominance, left-shifted granulopoiesis, eosinophilia and the cytogenetic analysis showed the following karyotype: 46, XY, t(8;13). The final diagnosis was a myeloproliferative syndrome with eosinophilia related to t(8;13) and T-cell acute lymphoblastic lymphoma (8p11 myeloproliferative syndrome). We review the relevant literature about this unusual entity.

Gene therapy in a murine model of chronic eosinophilic leukemia-not otherwise specified (CEL-NOS)

Chronic eosinophilic leukemia-not otherwise specified (CEL-NOS) is a rare, aggressive, fatal disease characterized by blood eosinophilia and dysfunction of organs infiltrated with eosinophils. Clinically, the disease manifests with weight loss, cough, weakness, diarrhea, and multi-organ dysfunction that is unresponsive to therapy. We developed a one-time gene therapy for CEL-NOS using an adeno-associated virus (AAV) expressing an anti-eosinophil monoclonal antibody (AAVrh.10mAnti-Eos) to provide sustained suppression of eosinophil numbers in blood, thus reducing eosinophil tissue invasion and organ dysfunction. A novel CEL-NOS model was developed in NOD-scid IL2rγ^null (NSG) mice by administration of AAV expressing the cytokine IL5 (AAVrh.10mIL5), resulting in marked peripheral and tissue eosinophilia of the heart, lung, liver, and spleen, and eventually death. Mice were administered AAVrh.10mAnti-Eos (10¹¹ genome copies) 4 wk after administration of AAVrh.10mIL5 and evaluated for anti-eosinophil antibody expression, blood eosinophil counts, organ eosinophil invasion, and survival. AAVrh.10mAnti-Eos expressed persistent levels of the anti-eosinophil antibody for >24 wk. Strikingly, CEL-NOS treated mice had markedly lower blood eosinophil levels and reduced mortality when compared with control treated mice. These results suggest that a single treatment with AAVrh.10mAnti-Eos has the potential to provide substantial therapeutic benefit to patients with CEL-NOS, a fatal malignant disorder.

Pruritus as a Presenting Symptom of FIP1L1-PDGFRA-Positive Chronic Eosinophilic Leukemia

Eosinophilia can be found in a variety of benign and malignant conditions, and a persistent eosinophilic count of more than 1500/mm³ necessitates additional investigation. Patients with FIP1L1-PDGFRA-positive chronic eosinophilic leukemia might present as asymptomatic or in a catastrophic state with multi-organ involvement. We present the case of a young male patient who was diagnosed with FIP1L1-PDGFRA chronic eosinophilic leukemia after a long history of recurrent cutaneous symptoms with no systemic signs.

World Health Organization-defined eosinophilic disorders: 2022 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary or clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 10⁹ /L. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, next generation sequencing gene assays, and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2016 World Health Organization endorses a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2", and the myeloproliferative neoplasm subtype, "chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (eg, < 1.5 × 10⁹ /L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, was recently approved by the US Food and Drug Administration for patients with idiopathic HES. The use of the IL-5 receptor antibody benralizumab, as well as other targeted therapies such as JAK2 and FGFR1 inhibitors, is under active investigation.

A Case of Acute Myeloid Leukemia Harboring a Rare Three-Way Translocation t(5;7;7) Involving the PDGFRB Gene and Successfully Treated with Imatinib

Platelet-derived growth factor-beta (PDGFRB) gene maps for the receptor tyrosine kinase PDGRFβ. PDGFRB gene fusions have been implicated in multiple myeloid and lymphoid neoplasms and have shown exquisite sensitivity to tyrosine kinase inhibitors. We report a case of a 29-year-old male who presented with acute myeloid leukemia who was eventually found to harbor a unique three-way translocation t(5;7;7)(q33.2;q32;q11.2) involving the PDGFRB gene. The patient initially achieved a complete response after induction with daunorubicin and cytarabine, but when he returned for consolidation, his white cell count had increased, and he was found to have an underlying myeloproliferative neoplasm. He was given consolidation with high-dose cytarabine and imatinib with excellent response, and ultimately received a matched unrelated donor transplant. The patient remains in remission to this day more than eight years later.

Latent Strongyloides stercoralis in an Asymptomatic Male With Chronic Peripheral Eosinophilia

Peripheral eosinophilia is a potentially concerning finding that can occur due to a multitude of causes. One such cause is latent helminth infections such as Strongyloides stercoralis. These parasites have broad distributions throughout the developing world, particularly South and Southeast Asia and it is estimated that roughly 200 million people have latent infections. We present the case of a 74-year-old patient from India who had asymptomatic eosinophilia since before 2006. He previously underwent an extensive workup which included testing for neoplasms, gene mutations, and lymphoproliferative disorders. After carefully examining the patient's travel history and demographic information, a parasite panel was administered which was positive for Strongyloides, thereby establishing a cause for his condition after years of expensive testing. Latent Strongyloides infections can lead to fatal dissemination if the host becomes immunocompromised. It is therefore essential to keep a detailed history of patient travel, occupation, and functional status when assessing peripheral eosinophilia so that obvious causes are not overlooked.