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A3386 - Ehrlichia - an Unusual Cause of Hemophagocytic Lymphohistiocytosis
Author Block: E. M. Wilfong1, J. C. Hewlett2, V. E. Kerchberger3, K. C. Bloch4, C. M. Sevin5; 1Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, TN, United States, 2Division of Pulmonary and Critical Care Medicine, Vanderbilt University, Nashville, TN, United States, 3Divison of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, TN, United States, 4Division of Infectious Disease, Vanderbilt University, Nashville, TN, United States, 5Vanderbilt Univ Med Ctr, Nashville, TN, United States.
Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a hemophagocytic syndrome characterized by mulitorgan system failure in the setting of dysregulation and activation of the mononuclear phagocytic syndrome. This syndrome can be associated with infections, malignancy, and autoimmune diseases. Here, we present a case of HLH triggered by Erlichia and review both our institutional experience and the prior literature.
Case: The patient is a 62 year-old woman with history of rheumatoid arthritis (on methotrexate and low-dose prednisone) and tick exposure who was brought to the ED for evaluation of worsening mental status. Upon arrival to the ED, she had multi-organ system dysfunction with creatinine 1.36 mg/dL (baseline 0.7 mg/dL), new transaminitis (AST 577, ALT 218), new lymphopenia (absolute lymphocyte count 30), new thrombocytopenia (platelet 35), and ARDS; she was admitted to the MICU for management. Emperic antibiotics were started including doxycycline; her buffy coat demonstrated Erlichia. Her clinical status worsened requiring vasopressors, continuous renal replacement therapy, and mechanical ventilation; a new seizure disorder also developed. She had a ferritin of 147,000 and elevated soluble IL-2 receptor of 4450 (normal range 45-1105). CMV was negative, and EBV titer was 9419. Hematology and infectious disease were consulted and felt that the clinical picture was consistent with HLH triggered by Ehrlichia. The patient was treated with dexamethasone and etoposide with clinical improvement in her cardiovascular, respiratory, and neurologic status. She was transferred out of the intensive care unit on hospital day 20. Unfortunately, she developed vancomycin resistant enterococcus sepsis and succumbed on hospital day 30.
Discussion: HLH is seen with various infections, but Ehrlichia is not a commonly described trigger. While this case represents the fourth case of Ehrlichia associated HLH at our institution since May 2017 (with one prior case in June 2015), there are only 8 adult cases reported in the literature. Thus, Ehrlichia may be an under recognized cause of HLH. At our institution, the mortality of Ehrlichia associated HLH is 60%, compared with 0% in the prior literature. Given the frequency of Ehrlichia associated HLH at Vanderbilt in 2017, we postulate that there may be a change in the organism or environment that has increased its predilection towards causing HLH. Intensivists should be familiar with the increased finding of HLH in patients with human mononuclear ehrlichiosis given the high mortality of this dual diagnosis and the need for monitoring and treatment best achieved in an intensive care unit.