Hypereosinophilia in Acute Lymphoblastic Leukemia: Two Cases with Review of Literature

Emerging Evidence for Pleiotropism of Eosinophils

Eosinophils are complex granulocytes with the capacity to react upon diverse stimuli due to their numerous and variable surface receptors, which allows them to respond in very different manners. Traditionally believed to be only part of parasitic and allergic/asthmatic immune responses, as scientific studies arise, the paradigm about these cells is continuously changing, adding layers of complexity to their roles in homeostasis and disease. Developing principally in the bone marrow by the action of IL-5 and granulocyte macrophage colony-stimulating factor GM-CSF, eosinophils migrate from the blood to very different organs, performing multiple functions in tissue homeostasis as in the gastrointestinal tract, thymus, uterus, mammary glands, liver, and skeletal muscle. In organs such as the lungs and gastrointestinal tract, eosinophils are able to act as immune regulatory cells and also to perform direct actions against parasites, and bacteria, where novel mechanisms of immune defense as extracellular DNA traps are key factors. Besides, eosinophils, are of importance in an effective response against viral pathogens by their nuclease enzymatic activity and have been lately described as involved in severe acute respiratory syndrome coronavirus SARS-CoV-2 immunity. The pleiotropic role of eosinophils is sustained because eosinophils can be also detrimental to human physiology, for example, in diseases like allergies, asthma, and eosinophilic esophagitis, where exosomes can be significant pathophysiologic units. These eosinophilic pathologies, require specific treatments by eosinophils control, such as new monoclonal antibodies like mepolizumab, reslizumab, and benralizumab. In this review, we describe the roles of eosinophils as effectors and regulatory cells and their involvement in pathological disorders and treatment.

A review on how to do hematology consults during COVID-19 pandemic

The ongoing COVID-19 pandemic is the most trending and talked topic across the World. From its point of origin in Wuhan, China to clinical laboratory at NIH, a mere six-month-old SARS-CoV-2 virus is keeping the clinicians, and scientists busy at various fronts. However, COVID-19 is an emerging and evolving disease and each day brings in more data, new figures, and findings from the field of clinical practice. The role of hematologists has been increasingly recognized during the current pandemic because of several reasons. Most important of them are the characteristic hematological findings of COVID-19 patients that also have prognostic implications and that were not seen in other viral infections. The treatment of hematological complications in COVID-19 patients is very challenging given the critical care setting. There are interim and limited guidelines thus far due to the novelty of the disease. As this remains to be a quite fluid situation, all the appropriate medical societies including the major hematology bodies are proposing initial and interim guidelines (e.g. ASH guideline). This puts a hematologist on consult service in a dubious position where, he/she must tailor the recommendations on case to case basis. The purpose of this review is to provide the background context about the impact of COVID-19 on the blood system and to summarize the current interim guidelines to manage the associated hematological issues in COVID-19 infection.

B-acute Lymphoblastic Leukemia With Hypereosinophilia Associated With Severe Cardiac Complications: A Clinical Case

Hypereosinophilia (HE) is rare but often secondary to a nonhematologic disease such as allergic disorders and parasitic infections. HE can also be associated with hematologic malignancies and be the result of a clonal proliferation or reactive to another hematologic condition. Association of HE with acute lymphoblastic leukemia (ALL) is rare in children. We reported a case of a teenager presented with HE secondary to B-ALL who experienced severe cardiac complications with severe absolute eosinophil count. We compared his clinical evolution with other published cases and we reported 2 mutations linked to B-ALL never described before in this context.

Acute Lymphoblastic Leukemia with Hypereosinophilia in a Child: Case Report and Literature Review

Background: Hypereosinophilia in children can be primary or secondary. Numerous malignant diseases can cause hypereosinophilia, but it is seldom caused by acute lymphoblastic leukemia (ALL). In the event of protracted hypereosinophilia, it is extremely important to make a correct differential diagnosis. Case presentation: We present the case of an 11-year-old boy of Moroccan origin with ALL with hypereosinophilic onset (eosinophils in peripheral blood, 10,000/µL) in the absence of other signs of neoplastic disease, and compare this case with 61 similar cases in the literature. Following hospital admission, the patient initially presented with headache-caused nocturnal awakenings, evening fever, and cough, and he also lost approximately 7 kg in weight in a month not associated with sweating or itching. We first performed bone marrow aspiration, which showed an increase in eosinophils without cellular morphological abnormalities, and bone marrow immunophenotyping showed that 4.5% of cells had a phenotype compatible with lymphoid blasts. A lumbar puncture was negative. Given the poor marrow involvement, it was necessary to repeat a new bone marrow aspiration two days later, which showed an increase in blasts to 14%. A concomitant bone marrow biopsy showed an infiltration of blasts typical of B-cell ALL equal to 20–30% with associated hypereosinophilia. Cytogenetic analysis showed an hyperdiploid karyotype: 53–55, XY, +X, add(1)(q21q25), +4, +9, +10, +14, +2, +1, +21/46, XY. Conclusions: ALL is one of the possible causes of persistent hypereosinophilia. In patients with ALL and hypereosinophilia, peripheral hypereosinophilia can precede the appearance of blasts. Due to the negative prognosis and the increased risk of complications in these patients, bone marrow aspiration and biopsy are recommended if common causes of secondary hypereosinophilia are excluded.

Eosinophils from Physiology to Disease: A Comprehensive Review

Despite being the second least represented granulocyte subpopulation in the circulating blood, eosinophils are receiving a growing interest from the scientific community, due to their complex pathophysiological role in a broad range of local and systemic inflammatory diseases as well as in cancer and thrombosis. Eosinophils are crucial for the control of parasitic infections, but increasing evidence suggests that they are also involved in vital defensive tasks against bacterial and viral pathogens including HIV. On the other side of the coin, eosinophil potential to provide a strong defensive response against invading microbes through the release of a large array of compounds can prove toxic to the host tissues and dysregulate haemostasis. Increasing knowledge of eosinophil biological behaviour is leading to major changes in established paradigms for the classification and diagnosis of several allergic and autoimmune diseases and has paved the way to a "golden age" of eosinophil-targeted agents. In this review, we provide a comprehensive update on the pathophysiological role of eosinophils in host defence, inflammation, and cancer and discuss potential clinical implications in light of recent therapeutic advances.

Hypereosinophilia in a Young Patient: Occam's Razor or Hickam's Dictum?

Hypereosinophilia is an uncommon clinical problem encountered in hematology practice. While most of such cases are secondary or reactive, a significant fraction of cases are due to clonal myeloproliferative disorders. We report a young patient who presented with marked hypereosinophilia and was investigated extensively for its cause. Finally a common tropical infection was responsible for such marked eosinophilia fulfilling the principle of Occam's razor. The case emphasizes the need to search for treatable reactive causes even in presence of marked hypereosinophilia in a tropical country.