Objective:To summarize the clinical features, treatments and prognoses of aggressive natural killer cell leukemia (ANKL) in children.Methods:Clinical data and follow-up results were retrospectively reviewed for one hospitalized case of ANKL in June 2019.Through a literature search, the relevant items were retrieved from the databases of China National Knowledge Infrastructure, WanFang and PubMed using the Chinese and English keywords of "aggressive natural killer cell leukemia" and "children" up to December 2021.Results:This 8-year-old girl was diagnosed with ANKL by flow cytometric immunophenotype and immunohistochemical stain.Fever was the initial manifestation accompanied by sallow complexion, fatigue, enlargement of liver, spleen and lymph node and hematopenia of three lines.Allogeneic hematopoietic stem cell transplantation (allo-HSCT) was performed after chemotherapy.As of April 2022, the child stayed in a disease-free survival state after follow-ups for over 2 years.The literature search finally yielded 7 eligible Chinese and 10 English reports with a total of 17 pediatric ANKLs.In this group, there were fever (n=15), rash (n=1), perineal mass (n=1) and diarrhea, vomiting and other digestive tract symptoms (n=1). Six cases were misdiagnosed during an early stage of disease.4 cases received chemotherapy alone, 3 cases received chemotherapy regimen for acute lymphoblastic leukemia, 1 child died and one death occurred after received chemotherapy regimen of "cisplatin + vincristine + doxorubicin + ifosfamide". Allo-HSCT was performed in 5 patients after remission with chemotherapy and one child died from multiple organ failure at 9 months after allo-HSCT.Nine cases gave up treatment.Conclusions:ANKL has a rapid disease progression, diverse clinical manifestations, easy misdiagnosis and poor prognosis.For suspected ANKL cases, clinicians perform multiple bone perforations at multiple sites and immunophenotype by flow cytometry as soon as possible to confirm the diagnosis.Currently allo-HSCT offers a long-term survival of ANKL patients.

Objective:To explore the clinical efficacy and safety of Ruxolitinib, a Janus kinase inhibitor, in combination with Methylprednisolone as a bridge to allogeneic hematopoietic stem cell transplantation (allo-HSCT) for relapsed/refractory Epstein-Barr virus-associated hemophagocytic syndrome (EBV-AHS) in pediatric patients.Methods:The clinical data of 4 patients with relapsed/refractory EBV-AHS treated with Ruxolitinib in combination with Methylprednisolone as a bridge to allo-HSCT at the Department of Pediatrics, the First Affiliated Hospital of Zhengzhou University from August 2018 to February 2020 were retrospectively analyzed, and the disease characteristics, diagnosis and treatment process, clinical experience and related research progress were analyzed and summarized.Results:Among 4 patients with relapsed/refractory EBV-AHS, 2 patients were treated with low-dose Ruxolitinb in combination with Methylprednisolone for 6-10 weeks after partial remission.The disease did not progress, and they survived after being bridged to allo-HSCT.One patient was treated with large-dose Ruxolitinib in combination with Methylprednisolone due to the intolerance to chemotherapy, with the biochemical indicators of hemophagocytic syndrome significantly improved, and then the bridging to allo-HSCT was performed 2 months ago and this patient survived.One patient with EBV-AHS relapsed was relieved by chemotherapy again, then was given maintenance therapy with Ruxolitinib and Methylprednisolone, but the condition still progressed and the treatment was ineffective.This patient underwent allo-HSCT for salvage treatment more than 1 year ago and survived.Except that 1 patient developed mild anemia, the other 3 patients had no significant Ruxolitinib-related toxicities.Conclusions:Ruxolitinib in combination with Methylprednisolone can be safely employed as a salvage treatment for pediatric patients with relapsed/refractory EBV-AHS and a bridge to allo-HSCT, which has favorable safety, efficacy and tolerance in clinical practice.