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A3388 - Successful Treatment of Hemophagocytic Lymphohistiocytosis Secondary to Ehrlichia Infection
Author Block: R. Samannan1, D. R. McCaffree2; 1Internal Medicine/Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States, 2Pulm Crit Care Section, Univ of Oklahoma Hlth Sciences Ctr, Oklahoma City, OK, United States.
Introduction: Hemophagocytic Lymphohistiocytosis (HLH) is a rare and potentially fatal syndrome caused by uncontrolled hyper inflammatory response leading to dysregulated activation of the mononuclear macrophage system. It can be primary or secondary based on presence of absence of genetic mutations. Ehrlichia as an etiology for secondary HLH is extremely rare. Here we describe successful treatment of a patient with secondary HLH triggered by Ehrlichia chaffeensis.
Case report: A 51 year old Caucasian female presented to the hospital with altered mental status and septic shock. She was intubated and started on vasopressors. Evaluation showed pancytopenia (WBC 890 cells/ cu.mm, Platelet of 92 K cells /cu.mm, Hb. of 8gm/dl), evidence of multi organ injury with severe transamniitis (AST 1600U/L, ALT 330U/L), BUN 77mg/dl, elevated creatinine 2.5 mg/dl, ferritin at 16500ng/ml, Serum triglycerides at 382 mg/dl. She was coagulopathic with INR at 1.8, Fibrinogen was low at 129 mg/dl with elevated D-dimer at 7803ng/ml. Peripheral smear negative for schistocytes. CT chest showed minimal pleural effusion. Broad spectrum antibiotics were initiated with Vancomycin and Piperacillin/tazobacam. Due to history of tick bite Doxycyclin was added. Due to concerns for HLH, bone marrow biopsy was done on day 2 of hospitalization which showed hemophagocytic macrophages. Ehrlichia PCR was positive. She was diagnosed with HLH secondary to Ehrlichia infection and started on Etoposide and dexamethasone on day 3 of hospitalization and antibiotics were deescalated to doxycycline after cultures were negative. Soluble IL-2 receptor returned elevated at 6618 U/ml. Genetic panel for primary HLH was negative. The patient made a complete clinical recovery and was discharged home on day 19 of hospitalization.
Discussion: The major causes of secondary HLH are infections and malignancy. Bacterial infections account for less than 10% of adult HLH. Ehrlichia as a cause of HLH is extremely rare.
Human Monocytotropic Ehrlichiosis (HME), is caused by E. chaffeensis, and transmitted by the lone star tick (Ambyloma americanum). HME has a case-mortality rate of 1.9%. The prognosis worsens if treatment is delayed with doxycycline.
The treatment protocols for HLH comprise of chemotherapeutic agents - etoposide, cyclosporine and dexamethasone. They cause selective depletion of abnormally activated T cells and calm the cytokine surge. To prevent fatal outcomes treatment must be started when HLH is suspected.
In summary, HME as an etiology of HLH can be easily overlooked. This case highlights the importance of early recognition and prompt treatment of the underlying cause of this syndrome.