Case Western Reserve University and University Hospitals of Cleveland Poster 427: Enterococcus AS an Infectious trigger for HEmophagocytic Lymphohistiocytosis in AML patients post Allogeneic Hematopeitic stem cell transplant Lubna Mehyar MD, Hasan Hashem MD, Irina Pateva MD, Peter De Blank MD, Jignesh Dalal MD Pediatric Hematology Oncology Case Western Reserve University and University Hospitals of Cleveland CONCLUSIONS HLH is a rare entity and its occurrence in patients post HSCT is frequently associated with infectious complications. We describe the first two cases to our knowledge with enterococcus associated HLH post HSCT. HLH is difficult to recognize and is likely under-diagnosed. We advocate for high level of suspicion in patients post HSCT who develop multiorgan failure and early initiation of appropriate therapy. OBJECTIVE To describe two AML patients who developed IA-HLH post HSCT. Both patients had Enterococcus bacteremia at the time when HLH occurred, which has not been described in the medical literature previously. BACKGROUND Hemophagocytic Lymphohistiocytosis is a rare, potentially fatal syndrome. It is classified as primary (genetic) or secondary. The latter is related to infections, malignancies, rheumatologic and metabolic diseases. Infection associated HLH post HSCT has been described to occur with a variety of pathogens including bacteria, viruses, fungi and protozoa. Association between enterococcus and HLH post transplant is not well characterized like EBV or fungal associated HLH. Inflammasome or nod2/ card15 pathways stimulation have been suggested in macrophage activation syndrome in the setting of enterococcus sepsis in one reported case of cryopyrin-associated periodic syndrome (CAPS) which could have a similar pathway in the development of HLH. RESULTS As shown in tables below. Cases Diagnosis in 2014 AML Treatment HSCT Donors and outcomes Preparative regimen GVHD prophylaxis Complications during transplant HLH Treatment 6y/o F AML with chloroma of the jaw COG treatment protocol Three HSCTs; third transplant was 6/10 haploidentical bone marrow   Graft failure X3 RIC Tacrolimus MMF BK viruria/viremia Disseminated mucormycosis VRE bacteremia/pneumonia HHV-6 viremia. Encephalopathy Multiorgan failure HLH at T+15 of third transplant Expired T+21 post third transplant Dexamethasone IVIG Antimicrobials Antifungals 23 y/o F Relapsed AML, 8 years off treatment 2006, COG clinical trial; 2014, re-induction with FLAG therapy followed by Cytarabine with Asparaginase 4/6 HLA matched double UCBT Engrafted on T+21 Tacrolimus MMF BK viremia/viruria Transplant Associated Microangiopathy Vancomycin sensitive Enterococcus faecium sepsis HLH at T+40 Expired T+56 Plasmapheresis Table 1: Cases summary. UCBT: Unrelated Cord Blood Transplant, RIC: Reduced Intensity Conditioning, COG: Children’s Oncology Group. HLH criteria Fever ᵒC Cytopenias Ferritin ug/L Fibrinogen mg/dL Triglycerides Soluble IL-2 U/ml Coagulation profile Direct bilirubin Bone Marrow Case 1 40.7 WBC<0.1x10E9/L, Hb 9.3g/dL, platelets 42x10E9/L >40,000 865 1185 7780 Normal 6.3 Hypocellular Case 2 39 WBC 32x10E9/L, Hb 8.6g/dL, platelets 20x10E9/L 88 275 1073 Schistocytes, ↑ D-dimer, PT, LDH 8.2 Not performed   Table 2: HLH helpful criteria in our cases.