Leukemoid reaction: spectrum and prognosis of 173 adult patients

Chronic neutrophilic leukemia and atypical chronic myeloid leukemia: 2024 update on diagnosis, genetics, risk stratification, and management

Chronic neutrophilic leukemia (CNL) is a rare BCR::ABL1-negative myeloproliferative neoplasm (MPN) defined by persistent mature neutrophilic leukocytosis and bone marrow granulocyte hyperplasia. Atypical chronic myeloid leukemia (aCML) (myelodysplastic "[MDS]/MPN with neutrophilia" per World Health Organization [WHO]) is a MDS/MPN overlap disorder featuring dysplastic neutrophilia and circulating myeloid precursors. Both manifest with frequent hepatosplenomegaly and less commonly, bleeding, with high rates of leukemic transformation and death. The 2022 revised WHO classification conserved CNL diagnostic criteria of leukocytosis ≥25 × 109/L, neutrophils ≥80% with <10% circulating precursors, absence of dysplasia, and presence of an activating CSF3R mutation. ICC criteria are harmonized with those of other myeloid entities, with a key distinction being lower leukocytosis threshold (≥13 × 109/L) for cases CSF3R-mutated. Criteria for aCML include leukocytosis ≥13 × 109/L, dysgranulopoiesis, circulating myeloid precursors ≥10%, and at least one cytopenia for MDS-thresholds (ICC). In both classifications ASXL1 and SETBP1 (ICC), or SETBP1 ± ETNK1 (WHO) mutations can be used to support the diagnosis. Both diseases show hypercellular bone marrow due to a granulocytic proliferation, aCML distinguished by dysplasia in granulocytes ± other lineages. Absence of monocytosis, rare/no basophilia, or eosinophilia, <20% blasts, and exclusion of other MPN, MDS/MPN, and tyrosine kinase fusions, are mandated. Cytogenetic abnormalities are identified in ~1/3 of CNL and ~15-40% of aCML patients. The molecular signature of CNL is a driver mutation in colony-stimulating factor 3 receptor-classically T618I, documented in >80% of cases. Atypical CML harbors a complex genomic backdrop with high rates of recurrent somatic mutations in ASXL1, SETBP1, TET2, SRSF2, EZH2, and less frequently in ETNK1. Leukemic transformation rates are ~10-25% and 30-40% for CNL and aCML, respectively. Overall survival is poor: 15-31 months in CNL and 12-20 months in aCML. The Mayo Clinic CNL risk model for survival stratifies patients according to platelets <160 × 109/L (2 points), leukocytes >60 × 109/L (1 point), and ASXL1 mutation (1 point); distinguishing low- (0-1 points) versus high-risk (2-4 points) categories. The Mayo Clinic aCML risk model attributes 1 point each for: age >67 years, hemoglobin <10 g/dL, and TET2 mutation, delineating low- (0-1 risk factor) and high-risk (≥2 risk factors) subgroups. Management is risk-driven and symptom-directed, with no current standard of care. Most commonly used agents include hydroxyurea, interferon, Janus kinase inhibitors, and hypomethylating agents, though none are disease-modifying. Hematopoietic stem cell transplant is the only potentially curative modality and should be considered in eligible patients. Recent genetic profiling has disclosed CBL, CEBPA, EZH2, NRAS, TET2, and U2AF1 to represent high-risk mutations in both entities. Actionable mutations (NRAS/KRAS, ETNK1) have also been identified, supporting novel agents targeting involved pathways. Preclinical and clinical studies evaluating new drugs (e.g., fedratinib, phase 2) and combinations are detailed.

A Predictive Algorithm for Discriminating Myeloid Malignancies and Leukemoid Reactions

BACKGROUND

Adults presenting with a neutrophil-predominant leukocytosis (white cell count >50,000/μL) often necessitate urgent medical management. These patients are diagnosed with either acute presentations of chronic myeloid malignancies or leukemoid reactions, yet accurate models to distinguish between these entities do not exist. We used demographic and lab data to build a machine learning model capable of discriminating between these diagnoses.

METHODS

The medical record at a tertiary care medical center was queried to identify adults with instances of white counts greater than 50,000/μL and >50% neutrophils from 2000 to 2021. For each patient, a full set of demographic and lab values were extracted at the time of their first presentation with a white count >50,000/μL. We generated a series of models in which the parameters most predictive of myeloid malignancies were identified, and a supervised machine learning approach was applied to the dataset.

RESULTS

Our best model-using a support vector machine algorithm-produced a sensitivity of 96% and a specificity of 95.9% (area under the curve = 0.982) for identifying myeloid malignancies. We also identified a clinically meaningful and significant disparity in outcomes based on diagnosis-a 6-fold increase in 12-month mortality in those diagnosed with leukemoid reactions.

CONCLUSIONS

These findings need to be validated but fill an unmet need for timely and accurate diagnosis in the setting of profound, neutrophil-predominant leukocytosis and support the use of predictive models as a means to improve patient outcomes.

Extreme leukocytosis in pregnancy: Is it always sinister?

Leukemoid reaction in pregnancy is a rare entity which must be diagnosed to mitigate the risks and costs of unnecessary antibiotics and prolonged hospital stays.

A Rare Case of Leukemoid Reaction During Mechanical Circulatory Support in a Patient With Severe Heart Failure: An Autopsy Study

The leukemoid reaction (LR) is reported to be caused by severe stress conditions such as infection, malignancies, intoxication, severe hemorrhage, or acute hemolysis; this condition is attributed to a very severe prognosis. Some reports have suggested that the LR was associated with a systemic stress response. A 36-year-old man who required mechanical circulatory support (MCS), including veno-arterial extracorporeal membrane oxygenation and Impella 5.5 due to severe heart failure, was transferred to our hospital. He showed a markedly elevated WBC count and died of multiple organ failure. The autopsy revealed the possibility that leukocytosis might have been due to an LR; however, the cause of the cardiac failure was unknown. To the best of our knowledge, this study is the first to report a rare case of LR in a patient with severe heart failure requiring MCS.

Does this patient have Clostridioides difficile infection? A systematic review and meta-analysis

BACKGROUND

The clinical features and predictors of Clostridioides difficile infection overlap with many conditions.

OBJECTIVES

We performed a systematic review to evaluate the diagnostic utility of clinical features (clinical examination, risk factors, laboratory tests, and radiographic findings) associated with C. difficile.

METHODS

Systematic review and meta-analysis of diagnostic features for C. difficile.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and Cochrane databases were searched up to September 2021.

STUDY ELIGIBILITY CRITERIA

Studies that reported clinical features of C. difficile, a valid reference standard test for confirming diagnosis of C. difficile, and a comparison among patients with a positive and negative test result.

PARTICIPANTS

Adult and paediatric patients across diverse clinical settings.

OUTCOMES

Sensitivity, specificity, likelihood ratios.

REFERENCE STANDARD

Stool nucleic acid amplification tests, enzyme immunoassays, cell cytotoxicity assay, and stool toxigenic culture.

ASSESSMENT OF RISK OF BIAS

Rational Clinical Examination Series and Quality Assessment of Diagnostic Accuracy Studies-2.

METHODS OF DATA SYNTHESIS

Univariate and bivariate analyses.

RESULTS

We screened 11 231 articles of which 40 were included, enabling the evaluation of 66 features for their diagnostic utility for C. difficile (10 clinical examination findings, 4 laboratory tests, 10 radiographic findings, prior exposure to 13 antibiotic types, and 29 clinical risk factors). Of the ten features identified on clinical examination, none were significantly clinically associated with increased likelihood of C. difficile infection. Some features that increased likelihood of C. difficile infection were stool leukocytes (LR+ 5.31, 95% CI 3.29-8.56) and hospital admission in the prior 3 months (LR+ 2.14, 95% CI 1.48-3.11). Several radiographic findings also strongly increased the likelihood of C. difficile infection like ascites (LR+ 2.91, 95% CI 1.89-4.49).

DISCUSSION

There is limited utility of bedside clinical examination alone in detecting C. difficile infection. Accurate diagnosis of C. difficile infection requires thoughtful clinical assessment for interpretation of microbiologic testing in all suspected cases.

Etiologies of Extreme Leukocytosis

OBJECTIVE

The objective of this study was to determine the etiologies and co-morbidities associated with extreme leukocytosis, which is characterized by a white blood cell (WBC) count ≥ 35 × 10⁹ leukocytes/L.  Method: Retrospective chart review was conducted for all patients, aged 18 years and older, admitted to the internal medicine department between 2015 and 2021 with an elevated WBC count ≥ 35 × 10⁹ leukocytes/L within the first 24 hours of admission.  Results: Eighty patients were identified to have WBC count ≥ 35 × 10⁹ leukocytes/L. The overall mortality was 16% and increased to 30% in those presenting with shock. Mortality increased from 2.8% in patients with WBC count in the range of 35-39.9 × 10⁹ leukocytes/L to 33% in those with WBC count in the range of 40-50 × 10⁹ leukocytes/L. There was no correlation with underlying co-morbidities or age. Pneumonia was the most common infection (38%), followed by UTI or pyelonephritis (28%) and abscesses (10%). There was no predominant organism responsible for these infections. The most common etiology for WBC count between 35-39.9 × 10⁹ leukocytes/L and 40-50 × 10⁹ leukocytes/L was infections, while malignancies (especially chronic lymphocytic leukemia) were more common with WBC count > 50 × 10⁹ leukocytes/L.  Conclusion: For WBC counts in the range of 35-50 × 10⁹ leukocytes/L, infections were the main reason for admission to the internal medicine department. Mortality increased from 2.8% to 33% as WBC counts increased from 35-39.9 × 10⁹ leukocytes/L to 40-50 × 10⁹ leukocytes/L. Overall, mortality for all WBC counts ≥ 35 × 10⁹ leukocytes/L was 16%. The most common infections were pneumonia, followed by UTI or pyelonephritis and abscesses. The underlying risk factors did not correlate with WBC counts or mortality.

Mycoplasma pneumonia with severe cold agglutinin hemolysis, thrombocytosis, leukemoid reaction and acute renal failure

Mycoplasma pneumoniae (M. pneumoniae) is a common cause of community acquired pneumonia and although most cases are mild, complications sometimes occur. Cold agglutinin hemolysis is a known complication of M. pneumoniae infection, and usually presents as a mild and transient hemolysis. Here we present a case of infection with M. pneumoniae in a 64-year-old male that caused life threatening hemolysis that required multiple blood transfusions. The patient also presented with acute kidney failure and a marked leukemoid reaction and thrombocytosis. This is a very rare combination of symptoms that could have led the clinicians to suspect a more virulent etiology than M. pneumoniae, thereby delaying adequate antibiotic treatment.

Welder's Anthrax: A Tale of 2 Cases

Bacillus anthracis has traditionally been considered the etiologic agent of anthrax. However, anthrax-like illness has been documented in welders and other metal workers infected with Bacillus cereus group spp. harboring pXO1 virulence genes that produce anthrax toxins. We present 2 recent cases of severe pneumonia in welders with B. cereus group infections and discuss potential risk factors for infection and treatment options, including antitoxin.

Clinical Features of Patients Hospitalized for All Routes of Anthrax, 1880-2018: A Systematic Review

BACKGROUND

Anthrax is a toxin-mediated zoonotic disease caused by Bacillus anthracis, with a worldwide distribution recognized for millennia. Bacillus anthracis is considered a potential biowarfare agent.

METHODS

We completed a systematic review for clinical and demographic characteristics of adults and children hospitalized with anthrax (cutaneous, inhalation, ingestion, injection [from contaminated heroin], primary meningitis) abstracted from published case reports, case series, and line lists in English from 1880 through 2018, assessing treatment impact by type and severity of disease. We analyzed geographic distribution, route of infection, exposure to anthrax, and incubation period.

RESULTS

Data on 764 adults and 167 children were reviewed. Most cases reported for 1880 through 1915 were from Europe; those for 1916 through 1950 were from North America; and from 1951 on, cases were from Asia. Cutaneous was the most common form of anthrax for all populations. Since 1960, adult anthrax mortality has ranged from 31% for cutaneous to 90% for primary meningitis. Median incubation periods ranged from 1 day (interquartile range [IQR], 0-4) for injection to 7 days (IQR, 4-9) for inhalation anthrax. Most patients with inhalation anthrax developed pleural effusions and more than half with ingestion anthrax developed ascites. Treatment and critical care advances have improved survival for those with systemic symptoms, from approximately 30% in those untreated to approximately 70% in those receiving antimicrobials or antiserum/antitoxin.

CONCLUSIONS

This review provides an improved evidence base for both clinical care of individual anthrax patients and public health planning for wide-area aerosol releases of B. anthracis spores.

Time to Look for Another Infectious Source? White Blood Cell Trends during Ventilator-Associated Pneumonia

Background: Ventilator-associated pneumonia (VAP) continues to plague patients in intensive care units (ICUs) throughout the world. Persistent leukocytosis despite antibiotic treatment for VAP can have many etiologies including normal inflammatory response, inadequate VAP antimicrobial therapy, and the presence of additional infectious diagnoses. Hypothesis: Surgical patients with VAP and a second infectious source have a different white blood cell count (WBC) trend than patients with VAP alone. Patients and Methods: Retrospective, single-center study of surgical ICU patients diagnosed with VAP (>10⁴ CFU/mL on semi-quantitative culture) between January 2019 and June 2020. Chart review identified additional infections diagnosed during VAP treatment. White blood cell count values were compared between patients treated for VAP alone (VAP-alone) and those with additional infections (VAP-plus) using a Wilcoxon test. Univariable analysis compared admission type, surgeries, and steroid use between cohorts. Results: Eighty-eight VAPs were included for analysis; 61 (69%) were VAP-alone and 27 (31%) VAP-plus. Average age was 47.1 ± 16.7 years, 78% were male, and 93% were trauma admissions. Median hospital day of VAP diagnosis was six (interquartile range [IQR], 4-10). Nearly all patients (99%) were started on initial antibiotic agents to which the VAP organism was sensitive. Daily WBC was higher for VAP-plus compared with VAP-alone on days five, six, and seven of treatment. The maximum WBC was higher for VAP-plus (21.6 k/mcL vs. 16.1 k/mcL; p = 0.02). There were no differences in admission types, number of surgeries, or steroid use between groups. Conclusions: Providers should have increased suspicion for additional sources of infection when ICU patients with a VAP continue to have elevated WBC despite appropriate antibiotic therapy.

Moderate to severe leukocytosis with vasopressor use is associated with increased mortality in trauma patients

Background

Leukocytosis is a rise in white blood cell (WBC) count and clinical outcomes of moderate to severe leukocytosis in trauma patients have not been described. We hypothesized that trauma patients with severe leukocytosis (SL; ≥40.0 × 109 leukocytes/L) have higher rates of in-hospital complications and mortality than those with moderate leukocytosis (ML; 25.0-39 × 109 leukocytes/L).

Methods

We performed a retrospective analysis (2010-2017) on trauma patients developing ML or SL at a single Level-I trauma center. A multivariable logistic regression analysis for risk factors were performed.

Results

From 15,807 trauma admissions, 332 (2.1%) had ML or SL. Of these, 308 (92.8%) were ML and 24 (7.2%) were SL. Patients with ML and SL reached their peak WBC count in 1 and 10 days after admission respectively (p < 0.001). SL patients suffered higher rates of in-hospital complications (p < 0.05) and mortality compared to those without ML or SL (14.5% vs. 3.3%, p < 0.001). Between ML and SL, mortality rates rose with leukocytosis severity (13.3% vs. 29.2%, p = 0.03). Among all patients with ML or SL, vasopressor use was the strongest independent risk factor for mortality (OR 12.61, p < 0.001).

Conclusion

Clinicians should be weary of the increased mortality rates and in-hospital complications in SL patients. Among patients with ML or SL, vasopressor use, rather than SL, was the strongest predictor of mortality. Patients with ML had a quicker time course to peak leukocytosis compared to SL, suggesting these two entities to be distinct in etiology and outcome, warranting future research.

Pediatric Myeloproliferative Neoplasms

Myeloproliferative neoplasms can present early in life and may present a diagnostic challenge. Very few studies have focused on the diagnosis, prognosis, and therapy for pediatric myeloproliferative neoplasms. This article focuses on chronic myeloid leukemia, essential thrombocythemia, polycythemia vera, and primary myelofibrosis in children.

Leukemoid Reaction in a Patient With Severe COVID-19 Infection

Leukemoid reaction is a rare clinical condition defined by marked leukocytosis with predominantly mature neutrophils. It is an uncommon condition with reported incidence of less than 1% in hospitalized patients. The major causes of leukemoid reaction are severe infection (clostridium difficile colitis, tuberculosis, or severe shigellosis), malignancies, intoxication, and severe hemorrhage. This article presents a case report of a 64-year-old female with severe COVID-19 infection who presented with marked leukocytosis. After extensive workup to exclude hematologic malignancy, the patient was diagnosed to have a leukemoid reaction.

Elevated white blood cell count does not predict Clostridium difficile nucleic acid testing results

BACKGROUND

An elevated white blood cell count (>15 thousand/μL) is an established prognostic marker in patients with Clostridium difficile infection (CDI). Small observational studies have suggested that a markedly elevated WBC should prompt consideration of CDI. However, there is limited evidence correlating WBC elevation with the results of C. difficile nucleic acid testing (NAAT).

METHODS

Retrospective review of laboratory testing, outcomes, and treatment of 16,568 consecutive patients presenting to 4 hospitals over four years with NAAT and WBC testing on the same day.

RESULTS

No significant relationship between C. difficile NAAT results and concurrent WBC in the inpatient setting was observed. Although an elevated WBC did predict NAAT results in the outpatient and emergency department populations (p<0.001), accuracy was poor, with receiver-operator areas under the curve of 0.59 and 0.56. An elevated WBC (>15 thousand/μL) in CDI was associated with a longer median hospital length of stay (15.5 vs. 11.0 days, p<0.01), consistent with leukocytosis as a prognostic marker in CDI. NAAT-positive inpatients with elevated WBC were more likely to be treated with metronidazole and/or vancomycin (relative ratio 1.2, 95% confidence interval 1.1-1.3) and die in the hospital (relative ratio 2.9, 95% CI 2.0-4.3).

CONCLUSIONS

Although WBC is an important prognostic indicator in patients with CDI, an isolated WBC elevation has low sensitivity and specificity as a predictor of fecal C. difficile NAAT positivity in the inpatient setting. A high or rising WBC in isolation is not a sufficient indication for CDI testing.

Rare Case of Leukemoid Reaction in a Patient With Severe Alcoholic Hepatitis

Alcoholic hepatitis results from excessive alcohol consumption in patients with or without underlying chronic liver disease. Leukemoid reactions have been associated with poor outcomes in severe alcoholic hepatitis. There are only a handful of reported cases describing this relationship, and the striking similarity in these cases was a high short-term mortality rate. We believe that these patients represent a unique subgroup of patients with alcoholic hepatitis and that leukemoid reaction is a poor prognostic indicator in this condition. Here, we describe a case of 55-year-old male with severe alcoholic hepatitis with superimposed candida esophagitis who was found to have leukemoid reaction during diagnostic workup.

A prospective study of hospitalized patients with leukemoid reaction; causes, prognosis and value of manual peripheral smear review

INTRODUCTION

Several diagnoses have been associated with leukemoid reaction (LR). In patients with LR the diagnostic and prognostic value of detailed manual blood smear counts (such as the percentage of band cells or grading of neutrophil toxic changes) has not been studied previously.

METHODS

We prospectively recorded all hospitalized adult (> 18 years old) patients with LR (≥ 30000/ul) of neutrophilic predominance, excluding patients with pre-existing leukocytosis due to hematological malignancies. We examined the diagnoses and prognosis (in-hospital mortality and post-discharge mortality up to a year after the end of the study) of these patients as well as the value of manual peripheral smear review.

RESULTS

We recorded a total of 93 patients with LR from January 2017 to December 2017. Infection was the most common diagnosis (70%), followed by malignancy (7.5%) and bleeding (6.5%). In-hospital mortality (45%) and post-discharge mortality (35% of those discharged) were very high. Among blood smear findings, only neutrophil vacuolation was significantly more common in patients with infections (34%), although it was also observed in many patients without any infection (13%). Blood smear findings were not associated with prognosis.

CONCLUSION

Detailed manual smear review is a labor-intensive procedure and it has limited diagnostic and prognostic value in unselected hospitalized patients with neutrophilic LR.

Leukemoid reaction: A 21st-century cohort study

INTRODUCTION

Leukemoid reaction (leukocyte count >50 cells ×10⁹  L) is a rare but extremely relevant finding. Since little has been published on this condition's clinical relevance and prognosis, we investigated leukemoid reaction in patients with a white blood cell count of >50 × 10⁹  L, including etiology and outcomes.

METHODS

This retrospective cohort study included all patients at a Brazilian tertiary hospital between January 2016 and July 2018 > 18 years with a total leukocyte count >50 cells×10⁹  L. Demographics, complete blood count, clinical features, and the exams used to diagnose and determine leukemoid reaction etiology were analyzed. A Kaplan-Meyer survival analysis was performed, and a binary logistic regression model identified variables associated with death.

RESULTS

Of the 267 cases with white blood cell count of >50 × 10⁹ , 162/267 (60%) were secondary to hematopoietic neoplasm and 105/267 (40%) presenting as a true leukemoid reaction. The primary causes of the true leukemoid reaction cases were infection (59), nonhematopoietic neoplasm (17), or other causes (29). Patient deaths (66) differed significantly between groups (P < .001, log-rank [Mantel-Cox] Test). Lower hemoglobin, older age, and increased segmented neutrophil count were associated with increased risk of death.

CONCLUSIONS

This was a modern cohort analysis of leukemoid reactions, inclusive of all etiologies. The most common cause was infection, which involved several microorganisms. Paraneoplastic leukemoid reaction was also common. Both conditions have a poor prognosis with high mortality, being a major medical challenge.

Clinical Features of Neutrophilic Dermatosis Variants Resembling Necrotizing Fasciitis

Importance

Pyoderma gangrenosum and necrotizing Sweet syndrome are diagnostically challenging variants of neutrophilic dermatosis that can clinically mimic the cutaneous and systemic features of necrotizing fasciitis. Improved characterization of these rare variants is needed, as improper diagnosis may lead to inappropriate or delayed treatment and the potential for morbidity.

Objective

To determine the characteristics of necrotizing neutrophilic dermatosis to improve diagnostic accuracy and distinguish from infection.

Design, Setting, and Participants

A case series of patients with necrotizing neutrophilic dermatosis treated at 3 academic hospitals (University of California San Francisco, Oregon Health and Science University, and University of Minnesota) from January 1, 2015, to December 31, 2017, was performed along with a literature review of related articles published between January 1, 1980, and December 31, 2017. Data were obtained from medical records as well as Medline and Embase databases. All patients had signs resembling necrotizing infection and had a final diagnosis of pyoderma gangrenosum with systemic features or necrotizing Sweet syndrome. Patients were excluded if a diagnosis other than neutrophilic dermatosis was made, if key clinical information was missing, and if reported in a non-English language.

Main Outcomes and Measures

Description of key characteristics of necrotizing neutrophilic dermatosis.

Results

Overall, 54 patients with necrotizing neutrophilic dermatosis were included, of which 40 had pyoderma gangrenosum with systemic features and 14 had necrotizing Sweet syndrome. Of the 54 patients, 29 (54%) were male and 25 (46%) were female, with a mean (SD) age of 51 (19) years. Skin lesions commonly occurred on the lower (19 [35%]) and upper (13 [24%]) extremities and developed after a surgical procedure (22 [41%]) or skin trauma (10 [19%]). Shock was reported in 14 patients (26%), and leukemoid reaction was seen in 15 patients (28%). Of the patients with necrotizing neutrophilic dermatosis, 51 (94%) were initially misdiagnosed as necrotizing fasciitis and subsequently received inappropriate treatment. Debridement was performed in 42 patients (78%), with a mean (SD) of 2 (2 [range, 1-12]) debridements per patient. Four amputations (7%) were performed. Forty-nine patients (91%) received antibiotics when necrotizing neutrophilic dermatosis was misdiagnosed as an infection, and 50 patients (93%) received systemic corticosteroids; all patients responded to immunosuppressants.

Conclusions and Relevance

A complex spectrum of clinical findings of pyoderma gangrenosum and Sweet syndrome with prominent systemic inflammation exists that defines a new subset of neutrophilic dermatoses, termed necrotizing neutrophilic dermatoses; recognizing the difference between this variant and severe infection may prevent unnecessary surgical procedures and prolonged disease morbidity associated with a misdiagnosis and may expedite appropriate medical management.

Leukemoid reaction in the pediatric population: etiologies, outcome, and implications

Leukemoid reaction (WBC > 30,000/μL) may indicate significant medical conditions, mostly infectious. Prompted by the lack of population-based data on the presentation, characteristics, and necessary workup in children with leukemoid reaction, we searched the database of a tertiary pediatric medical center for all children presented with at least one WBC count of ≥ 30,000/μL in 2009-2014. Demographic, clinical, and laboratory parameters were recorded. Children admitted with WBC < 30,000/μL served as controls. Pneumonia was the most common diagnosis in the leukemoid reaction group, with a 5.5-fold higher prevalence of pleuropneumonia than in the control group. The leukemoid group had a longer average hospital stay (7.5 vs. 5.5 days). Patients with WBC ≥ 50,000/μL had a sixfold higher rate of leukemia than patients with a lower count. There was a significant association of leukemia with low platelet count, low levels of C-reactive protein, and high levels of uric acid and lactate dehydrogenase.

CONCLUSION

Children presented with a leukemoid reaction are at high risk of pneumonia, especially pleuropneumonia, and a long hospital stay. Those with WBC ≥ 50,000/μL have a sixfold higher risk of leukemia. For prompt diagnosis, clinicians should be aware of the variables associated with leukemia. What is Known: • Leukemoid reaction has been associated with infectious diseases. • Leukemoid reaction at presentation in adults is correlated with high morbidity and mortality. What is New: • Children with leukemoid reaction are at high risk of pleuropneumonia. • We did not observe increased mortality in children with a leukemoid reaction.

Syphilis infection in an HIV patient presenting with leukemoid reaction: Case report and review of the literature

Leukemoid reaction (LR) is an uncommon though dreadful sign for the treating physician, as it is related to increased mortality. In the few series that have addressed its incidence and clinical significance, infectious causes count for about half of the cases of LR, the rest accounting for cancer, drugs or rarer causes. In the HIV setting, it represents an even rarer event, owing probably to the impaired granulocytic response of AIDS patients to bacterial agents. However no report exists as to the incidence of LR to the immune-restored HIV patients adequately treated with antiretroviral therapy (ART). Syphilis is a well known cause of mild lymphocytosis, though only one report of LR exists in the congenital setting. We hereby report a case of an HIV patient adequately treated with ART, who presented with LR with a lymphomonocytic preponderance after infection with treponema pallidum.

Melanoma induced immunosuppression is mediated by hematopoietic dysregulation

Tumors are associated with expansion of immunosuppressive cells such as tumor associated macrophages (TAMs), regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs). These cells promote tumor growth, angiogenesis, metastasis and immune escape. Cancer patients frequently present symptoms such as anemia, leukocytosis and/or cytopenia; associated with poor prognosis. To uncover tumor-mediated hematopoietic abnormalities and identify novel targets that can be harnessed to improve tumor-specific immune responses, we investigated the hematopoietic stem and progenitor cell compartment in melanoma bearing mice. We show that melanoma growth results in expansion of myeloid lineages such as MDSCs, macrophages and DCs along with a reduction in mature RBCs and platelets. Mature B lymphocytes in the blood and BM of melanoma mice were also reduced. Mice bearing melanoma showed extramedullary hematopoiesis in the spleen. Increased expansion of myeloid lineages occurred directly at the level of stem and progenitor cells. The reduction in mature B lymphocytes resulted from a block at the Pro-B cell stage in the bone marrow. Addition of recombinant IL-3 to bone marrow cells resulted in the expansion of committed myeloid progenitors including common myeloid precursors, granulocyte-monocyte precursors and megakaryocyte-erythrocyte precursors. In vivo, IL-3 receptor stimulation in melanoma bearing mice using an IL-3 antibody also resulted in a robust expansion of committed myeloid progenitors and hematopoietic stem cells. Collectively our findings demonstrate that tumor growth plays a pivotal role in reprogramming the host immune system by impacting hematopoiesis directly at the level of stem cell compartment.

Leukemoid Reaction in a Pediatric Patient With Diabetic Ketoacidosis

Herein, we report a case of a 12-year-old girl who presented with diabetic ketoacidosis and a leukemoid reaction. Although this association has been described in a few adult patients, pediatric cases have not been reported. A leukemoid reaction is commonly defined as an elevation in the white blood cell count greater than 50,000/μL in response to severe illness or stress other than hematologic malignancy; it is considered to be mediated by various hormones, cytokines, and factors that are released in response to inciting triggers, such as acidosis. As highlighted in our report, distinguishing a benign leukemoid reaction from a hematologic malignancy and even tumor lysis syndrome, particularly in a setting of diabetic ketoacidosis, is crucial to ensuring safe and efficacious therapeutic interventions.

Snake bite mortality in children: beyond bite to needle time

OBJECTIVE

To study the clinical characteristics and predictors of mortality from snake bite envenomation in children.

DESIGN

Prospective observational study with a one-group cohort design.

SETTING

Paediatric intensive care unit of a tertiary care hospital in South India.

SUBJECTS

The study cohort consisted of 145 children (55 girls and 90 boys) <12 years of age with snake bite envenomation.

METHODS

Demographic and clinical details were recorded in a semistructured pro forma. Children were treated with polyvalent antisnake venom (ASV) as per WHO protocol. Details of treatment, complications and outcomes were recorded. Univariate analysis was done to identify statistical significance, and those variables found to be significant were analysed using binary logistic regression.

RESULTS

Russell's viper was the most common offending snake followed by hump-nosed pit viper. Features of haemotoxicity, neurotoxicity and combined haemotoxicity and neurotoxicity occurred in 68 (47%), 39 (26.9%) and 9 (6%) children, respectively. Acute kidney injury (AKI) occurred in 36 (25%) children. The mortality rate was 10.3%. On univariate analysis, nocturnal bites, severe leucocytosis on day 1, AKI, capillary leak syndrome and a need for more than 20 vials of ASV were significantly associated with mortality. On multivariate analysis, only severe leucocytosis on day 1 (OR 35.29; 95% CI 1.37 to 911.89) and AKI (OR 35.05 95% CI 1.74 to 706.93) were found to be independent predictors of mortality.

CONCLUSIONS

This study has identified two hitherto unrecognised risk factors-severe leucocytosis on day 1 and capillary leak syndrome. These findings need to be taken into consideration when planning management strategies for snake bite envenomation in children.

Role of the leukocyte response in normal and immunocompromised host after Clostridium difficile infection

Clostridium difficile is the leading cause of healthcare-associated infections in the United States. Clinically, C. difficile-associated disease can present as asymptomatic colonization, self-limited diarrheal illness or severe colitis (that may result in death). This variability in disease course and outcomes suggests that host factors play an important role as key determinants of disease severity. Currently, there are several scoring indices to estimate severity of C. difficile-associated disease. Leukocytosis and renal failure are considered to be the most important predictors of C. difficile disease severity in hosts with a normal immune system. The degree of leukocytosis which is considered significant for severe disease and how it is scored vary amongst scoring indices. None of the scores have been prospectively validated, and while total WBC count is useful to estimate the magnitude of the host response in most patient populations, in immune-compromised patients like those receiving chemotherapy, solid organ transplant patients or hematopoietic stem cell transplants the WBC response can be variable or even absent making this marker of severity difficult to interpret. Other cellular subsets like neutrophils, eosinophils and lymphocytes provide important information about the host immune status and play an important role in the immune response against C. difficile infection. However, under the current scoring systems the role of these cellular subsets have been underestimated and only total white blood cell counts are taken into account. In this review we highlight the role of host leukocyte response to C. difficile challenge in the normal and immunocompromised host, and propose possible ways that would allow for a better representation of the different immune cell subsets (neutrophils, lymphocytes and eosinophils) in the current scoring indices.

Sepsis and Other Infectious Disease Emergencies in the Elderly

Waning immunity and declining anatomic and physiologic defenses render the elder vulnerable to a wide range of infectious diseases. Clinical presentations are often atypical and muted, favoring global changes in mental status and function over febrile responses or localizing symptoms. This review encompasses early recognition, evaluation, and appropriate management of these common infections specifically in the context of elders presenting to the emergency department. With enhanced understanding and appreciation of the unique aspects of infections in the elderly, emergency physicians can play an integral part in reducing the morbidity and mortality associated with these often debilitating and life-threatening diseases.

Utility of immune response-derived biomarkers in the differential diagnosis of inflammatory disorders

Differentiating between inflammatory disorders is difficult, but important for a rational use of antimicrobial agents. Biomarkers reflecting the host immune response may offer an attractive strategy to predict the etiology of an inflammatory process and can thus be of help in decision making. We performed a review of the literature to evaluate the diagnostic value of inflammatory biomarkers in adult patients admitted to the hospital with suspected systemic acute infections. Elevated procalcitonin (PCT) concentrations indicate a bacterial infection in febrile patients with an auto-immune disease, rather than a disease flare. CD64 expression on neutrophils can discriminate between non-infectious systemic inflammation and sepsis, and limited evidence suggests the same for decoy receptor 3. PCT is useful for both diagnosing bacterial infection complicating influenza and guiding antibiotic treatment in lower respiratory tract infections in general. In undifferentiated illnesses, increased CD35 expression on neutrophils distinguishes bacterial from viral infections. Compared to bacterial infections, invasive fungal infections are characterized by low concentrations of PCT. No biomarker predicting a specific infecting agent could be identified.

Clinical conundrums in management of sepsis in the elderly

In 2012, surviving sepsis campaign came out with updated international guidelines for management of severe sepsis and septic shock. Paradoxically, there are no specific guidelines for management of sepsis in the elderly, although the elderly are more predisposed to sepsis, and morbidity and mortality related to sepsis. Sepsis in the elderly is, more often than not, complicated by clinical conundrums such as congestive heart failure (CHF), atrial fibrillation (AF), chronic kidney disease (CKD), acute kidney injury (AKI), delirium, dementia, ambulatory dysfunction, polypharmacy, malglycemia, nutritional deficiencies, and antibiotic resistance. Also, with recurrent admissions to the hospital and widespread use of antibiotics, the elderly are more susceptible to Clostridium difficile colitis.

[Extreme neutrophilia in cats - aetiology and prognosis]

OBJECTIVE

The aim of this retrospective study was to evaluate the aetiology and prognostic factors of extreme neutrophilia in cats.

MATERIAL AND METHODS

Patient data over a 5-year period (January 2008  -  December 2013) were reviewed. Cats with a neutrophil count > 40 x 10⁹/l were included. They were further assigned to four groups: "inflammation", "neoplasia", "immune-mediated diseases", "unknown aetiology". Clinical signs, rectal temperature, hospitalisation, duration of hospitalisation, survival, left-shift and toxicity of neutrophils were evaluated.

RESULTS

In total, 28/5185 cats (0.5%) displayed extreme neutrophilia with a mean neutrophil count of 48.5 x 10⁹/l (40.0-76.0 x 10⁹/l). The most common aetiology was a severe inflammation, as seen in 16/28 cats (57%), whereby peritonitis (5/15 cats, 31%) predominated. In cats with neoplastic diseases (9/28 cats, 32%), intestinal neoplasia with subsequent peritonitis was the most common diagnosis (4/9 cats, 44%). Diseases of unknown aetiology (2/28 cats, 7%) and immune-mediated diseases (1/28, 3.6%) were rare. The most common clinical indications included lethargy, anorexia, fever, and gastrointestinal signs. Rectal temperature ranged between 33.9  °C and 40.2   °C, whereby in 2/24 cats (8%) hyperthermia (> 39.3°C) and in 5/24 cats (21%) hypothermia (< 38.0°C) was observed. Hospitalisation occurred in 21/28 cats (75%) with a median duration of 5.5 days (1-30 days). In 24/28 cats, a manual differential count was performed. A left-shift and toxicity of neutrophils were seen in 23/24 cats (96%) and 21/24 cats (88%), respectively. The overall median survival rate was 50%, whereby the survival rate was significantly lower in cats with neoplasia than in those with inflammatory diseases (22% vs. 56%, p < 0.0001).

CLINICAL RELEVANCE

An extreme neutrophilia is rare. It is commonly caused by peritonitis due to foreign bodies or ruptured intestinal tumours (in particular, intestinal lymphomas) and is characterised by a high mortality.

Anaplastic large cell lymphoma with paraneoplastic neutrophilia: an association between IL-17 elevation and aggressive disease progression

We report a case of anaplastic large cell lymphoma (ALCL) with involvement of bone marrow, exhibiting extreme leukocytosis leading to death due to multi-organ failure within 1 week after admission. The patient had a history of rheumatoid arthritis, and had severe pneumonia at admission. To elucidate the basis for the observed extreme neutrophilia, we analysed the levels of several cytokines in serum samples taken from the patient at diagnosis. The patient exhibited an extreme increase in interleukin-17 (IL-17), one of the major regulatory cytokines for inflammation and neutrophil migration. Interestingly, a recent study revealed that anaplastic lymphoma kinase (ALK)-positive ALCL cells produce IL-17. IL-17 also contributes to treatment resistance in multiple types of cancer. Given these previous findings, our case may suggest a possible link between overproduction of IL-17 and an aggressive ALCL phenotype. Further studies will be required to determine whether serum IL-17 levels serve as a useful prognostic marker for ALCL.