Initial laboratory studies in the PICU revealed excessive hyperferritinemia (58360 ng/mL, reference range: 11.0-306.8 ng/mL), fever (up to 40.0℃), low natural killer (NK) cell activity (0.32 %, reference range: 5-26%), hypofibrinogenemia (0.84 g/l, reference range: 1.50-4.35 g/l), leukopenia (2.07×109/L, reference range: 3.5-9.5×109/L), neutropenia (0.92×109/L, reference range: 1.8-6.3×109/L) and thrombocytopenia (42×109/L, reference range: 125-350×109/L). In addition to these findings, the patient presented with hepatosplenomegaly, and bone marrow biopsy revealed the presence of hemophagocytosis, confirming her HLH diagnosis in accordance with the HLH-2004 guidelines [9]. As her plasma EBV-DNA loads were significantly elevated (3.82×106 copies/ml), she was suspected to be suffering from EBV-associated hemophagocytic syndrome. The diagnosis of liver failure was confirmed based upon a syndrome of jaundice, liver injury (elevated alanine transaminase (ALT) levels (921 U/L, reference range: 7-40 U/L), aspartate aminotransferase (AST) levels (2223 U/L, reference range: 13-35 U/L), total bilirubin (TBIL) levels (108.7 umol/L, reference range: 3.5-23.5 umol/L)) and coagulopathy (international normalized ratio (INR) values (1.92, reference range: 0.8-1.2)). The patient exhibited high levels of C reactive protein (CRP) (76.40 mg/L, reference range: 0-8 mg/L), procalcitonin (PCT) (2.73 ng/ml, reference range: 0-0.05 ng/ml), IL-6 (154.06 pg/ml, reference range: 0-5.4 pg/ml), IL-8 (32.67 pg/ml, reference range: 0-20.6 pg/ml), IL-10 (169.81 pg/ml, reference range: 0-12.9 pg/ml), and IFN-γ (4387.41 pg/ml, reference range: 0-23.1 pg/ml). A thoracic-abdominal computer tomography (CT) analysis revealed pulmonary inflammation and no evidence of tumors. Multiple blood and sputum cultures as well as the other viral polymerase chain reaction (PCR) tests for common respiratory viruses and cytomegalovirus (CMV) were all negative. Treatment with meropenem, norepinephrine, intravenous immunoglobulin (IVIG), ganciclovir, and dexamethasone as well as high-flow nasal cannula (HFNC) placement were initiated. However, these approaches were ineffective as evidenced by sustained fever, hypoxemia, and hypotension. Chemotherapy was recommended for the patient, but her parents refused and asked for other therapeutic options. In view of the refractory state of HLH and her poor general condition, we next sought to achieve the immediate suppression of hypercytokinemia. Accordingly, we commenced blood purification. Plasma exchange (PE) was initially considered, but PE could not be performed owing to reduced plasma separator access owing to the coronavirus disease 2019 (COVID-19) pandemic. As such, we tried to use hemoadsorption (HA330-II perfusion column, Zhuhai Health Sails Biotechnology Co., Ltd., Zhuhai, China) in this patient. Heparin sodium was employed for anticoagulation, and the patient was infused with platelets and fibrinogen prothrombin complex concentrate. On the second day of hospitalization, this hemoadsorption approach was implemented one time. After that, this hemoadsorption approach was implemented two more times over a three-day period. One day 1, she was in poor condition in terms of clinical symptoms and biochemical parameters. She also need high dose of norepinephrine to maintain the balance of cardiovascular function. On the fifth day, the patient exhibited significantly decreased levels of IL-6 (12.16 pg/ml), IL-8 (10.63 pg/ml), IL-10 (63.38 pg/ml), and IFN-γ (61.99 pg/ml) (Fig1). She was gradually weaned off norepinephrine treatment, and her fever disappeared while her total leukocyte and neutrophil counts increased. However, no significant improvement in liver function was observed (ALT 766 U/L, AST 1196 U/L, TBIL 170.54 umol/L, Fib 1.23 g/l), and inflammatory markers rebounded after hemoadsorption was terminated for two days, at which time the patient again developed a fever that reached as high as 40.0℃. At that time, her parents provided consent for chemotherapy (HLH-2004) treatment, which was initiated in combination with hemoadsorption. The hemoadsorption approach was implemented another three times over a 5-day period, and the patient’s condition gradually improved. On the 13th day, decreased levels of IL-10 (30.06 pg/ml) and IFN-γ (50.69 pg/ml) (Fig1), improvement of liver function (ALT 257 U/L, AST 393 U/L, TBIL 79.91 umol/L, Fib 1.45 g/l), and increased platelet counts were evident. She was discharged on day 40 after admission due to her good recovery status. The patient underwent an additional 30 days of chemotherapeutic treatment, and no disease recurrence was evident as of eight months post-discharge.