Incidence and clinical significance of reactive thrombocytosis in children aged 1 to 24 months, hospitalized for community-acquired infections

Essential Thrombocythemia in Children and Adolescents

Simple Summary

Among chronic Ph-negative myeloproliferative neoplasms, essential thrombocythemia is found in children with low but increasing incidence. The diagnostic and clinical features do not completely overlap with ET of adult age. A significant number of cases, in fact, do not meet the criteria of clonality, and many cases require extensive clinical evaluation to exclude secondary, reactive forms. Therefore, histological analysis of bone marrow biopsy is necessary, and its use should be enforced. The clinical course appears to be more benign, at least within the first decades of observation, with the incidence of thrombotic events being much lower than in adults (4 % vs. 30%). Hemorrhages are mostly irrelevant. Therefore, the management should be carefully adapted to the individual patient, balancing the risk of future complications with long-term collateral effects of any drug. This review analyzes the peculiarities of the disease facing similarities and differences with adult scenarios.

Abstract

This paper reviews the features of pediatric essential thrombocythemia (ET). ET is a rare disease in children, challenging pediatric and adult hematologists alike. The current WHO classification acknowledges classical Philadelphia-negative MPNs and defines diagnostic criteria, mainly encompassing adult cases. The presence of one of three driver mutations (JAK2V617F, CALR, and MPL mutations) represent the proof of clonality typical of ET. Pediatric ET cases are thus usually confronted by adult approaches. These can fit only some patients, because only 25–40% of cases present one of the driver mutations. The diagnosis of hereditary, familial thrombocytosis and the exclusion of reactive/secondary thrombocytosis must be part of the diagnostic process in children and can clarify most of the negative cases. Still, many children present a clinical, histological picture of ET, with a molecular triple wild-type status. Moreover, prognosis seems more benign, at least within the first few decades of follow-up. Thrombotic events are rare, and only minor hemorrhages are ordinarily observed. As per the management, the need to control symptoms must be balanced with the collateral effects of lifelong drug therapy. We conclude that these differences concert a compelling case for a very careful therapeutic approach and advocate for the importance of further cooperative studies.

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.

Update on current views and advances on RSV infection (Review)

Respiratory syncytial virus (RSV) infection represents an excellent paradigm of precision medicine in modern paediatrics and several clinical trials are currently performed in the prevention and management of RSV infection. A new taxonomic terminology for RSV was recently adopted, while the diagnostic and omics techniques have revealed new modalities in the early identification of RSV infections and for better understanding of the disease pathogenesis. Coordinated clinical and research efforts constitute an important step in limiting RSV global predominance, improving epidemiological surveillance, and advancing neonatal and paediatric care. This review article presents the key messages of the plenary lectures, oral presentations and posters of the '5th workshop on paediatric virology' (Sparta, Greece, 12th October 2019) organized by the Paediatric Virology Study Group, focusing on recent advances in the epidemiology, pathogenesis, diagnosis, prognosis, clinical management and prevention of RSV infection in childhood.

Essential Thrombocythemia in a Two-year-old Child, Responsive to Hydroxyurea but Not Aspirin

Essential thrombocythemia (ET) is a myeloproliferative neoplasm that occurs mostly in patients above the age of 50 years. Its incidence in children is very rare, with around 100 cases reported in the literature. High-risk patients are defined by previous life threatening major thrombotic or severe hemorrhagic complication or age > 60. Those patients probably benefit from cytoreductive therapy. On the other hand, antiplatelet drugs are recommended for patients with low risk group. Although rare, ET should be considered in the differential diagnosis of persistent thrombocytosis in children, even at a very young age. A constellation of clinical, pathologic, and molecular testing are essential for diagnosis. Given the rarity of these cases, there is currently no consensus for treatment guidelines in children, especially in asymptomatic patients. We describe a case of a two-year old girl who presented with unexplained, isolated thrombocytosis which persisted for eight years. Bone marrow biopsy demonstrated typical features of ET. Over the course of the disease, hydroxyurea, but not aspirin, showed better control of symptoms and lowered the platelets level.

Association between secondary thrombocytosis and viral respiratory tract infections in children

Secondary thrombocytosis (ST) is frequently observed in children with a variety of clinical conditions. The leading cause of ST is respiratory tract infection (RTI) in children. Nasopharyngeal aspirate samples were collected and assessed for common respiratory viruses. The relationships between virus infections and secondary thrombocytosis were analyzed retrospectively. The blood platelet count and the presence of respiratory viruses were determined for 3156 RTI patients, and 817 (25.9%) cases with platelet ≥500 × 10(9)/L were considered as the thrombocytosis group. Compared with the normal group, the detection rates of respiratory syncytial virus (RSV) and human rhinovirus (HRV) were significantly higher in the thrombocytosis group (P = 0.017 and 0.042, respectively). HRV single infection was a risk factor associated with thrombocytosis [odds ratio (OR) = 1.560, 95% confidence interval (CI) = 1.108-2.197]. Furthermore, ST was more likely to occur in younger patients who had clinical manifestations of wheezing and dyspnea and who had been diagnosed with bronchiolitis. Furthermore, the course of disease lasted longer in these patients. ST is associated with viral respiratory tract infections, especially RSV and HRV infections. HRV single infection is a risk factor associated with thrombocytosis.

Extreme reactive thrombocytosis in a healthy 6 year-old child

Thrombocytosis is usually found by chance in children. Reactive or secondary thrombocytosis is the more common form, with infectious diseases being the most prevalent cause of it. Regarding the number of platelets there are four degrees of thrombocytosis; in its extreme degree the number of platelets exceeds 1,000,000/mm³. We describe a case of extreme reactive thrombocytosis in a healthy 6-year-old child. He required critical care admission for diagnosis and treatment (maximum number of platelets 7,283,000/mm³). We review the different causes of thrombocytosis in childhood, the differential diagnosis, and the available treatments in case of extreme thrombocytosis.

[Extreme reactive thrombocytosis in a healthy 6 year-old child]

Thrombocytosis is usually a casual finding in children. Reactive or secondary thrombocytosis is the more common form, being the infections diseases the most prevalent cause of it. Regarding the number of platelets there are four degrees of thrombocytosis; in its extreme degree the number of platelets exceeds 1,000,000/mm(3). We describe a case of extreme reactive thrombocytosis in a healthy 6-year-old child. He required critical care admission for diagnosis and treatment (maximum number of platelets 7,283,000/mm(3)). We review the different causes of thrombocytosis in childhood, the differential diagnosis, and the available treatments in case of extreme thrombocytosis.

Associations of reactive thrombocytosis with clinical characteristics in pediatric diseases

BACKGROUND

Reactive thrombocytosis (RT) in pediatric patients is common, but usually without symptoms. The incidence of RT is different depending on age. Mostly, we reason that RT is a phenomenon, nevertheless the diagnostic value of RT is little known. Therefore, the aim of this study was to determine the association of RT and clinical or laboratory characteristics in pediatric diseases.

METHODS

We retrospectively analyzed the medical records of pediatric patients hospitalized at Wan Fang hospital from January 2002 to July 2009. Thrombocytosis was defined as a platelet count more than 500 × 10(9)/L. There were 822 patients enrolled to this study. The clinical parameters, including age, gender, disease type, and hospitalization days, were investigated. The association between RT and clinical manifestations and the relationship of leukocytes, hemoglobin, C-reactive protein, and platelet counts were analyzed.

RESULTS

The overall incidence of RT in hospitalized pediatric patients was 6.3%. Infants had a significantly higher incidence (11.3%, p<0.001). Mild RT was found in most patients (83.6%). Infections (75.4%) were the most common cause, followed by perinatal diseases (11.1%). The relationship of RT and age revealed a positive correlation (p=0.045, r=0.70 after adjustment). The degree of RT was an independent factor for hospitalization days (p<0.001, r=0.126 after adjustment). There was a positive correlation between white blood cell count and platelets (p=0.002, r=0.017); on the contrary, the relationship between hemoglobin level and platelets was an inverse correlation (p<0.001, r=-0.193).

CONCLUSIONS

In children, the degree of RT was associated with age, and patients had significantly longer hospitalization days in proportion to the increase in platelet count. Laboratory association revealed that the degree of RT was positively correlated to white cell count and negatively correlated to hemoglobin level. Therefore, the degree of RT might be a predictive factor with regard to hospitalization days in pediatric diseases.