Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of pathologic immune activation which occurs as either a familial disorder or sporadic condition. The diagnosis of HLH requires a presence of five out of eight criteria: fever, splenomegaly, pancytopenia, hypertriglyceridemia and/or hypofibrogenemia, hemophagocytosis in bone marrow, spleen or lymph nodes, low or absent natural killer cell activity, hyperferritinemia, and high level of soluble interleukin-2 receptor. We present a case of HLH triggered by severe infection with Ehrlichia chaffeensis in a patient taking methotrexate for seronegative spondyloarthropathy.
A 45-year-old man with a history of ankylosing spondylitis taking methotrexate presented to a community hospital with acute onset of nausea, vomiting and diarrhea. Physical examination revealed a febrile patient with diffuse abdominal tenderness with splenomegaly and diffuse maculopapular rash involving the trunk and all extremities. Labs showed leukopenia and thrombocytopenia. Clinical course was complicated by development of acute renal failure, altered mental status and hypoxic respiratory failure requiring endotracheal intubation and mechanical ventilation. Plasmapheresis was initiated due to concern for thrombotic thrombocytopenic purpura with no response. A bone marrow biopsy was performed which revealed a tri-lineage hematopoiesis with increased number of histiocytes, including hemophagocytic forms. Further lab abnormalities included a hypofibrinogenemia, hyperferritinemia, low complement protein C3 and C4, and hypertriglyceridemia. Patient met diagnostic criteria for HLH and was transferred to our tertiary care hospital for further management.
Given concern for tick borne disease, patient was started on doxycycline in addition to previously initiated broad spectrum antibiotics. Serum antibody testing was sent for Lyme disease, Rocky Mountain spotted fever and human Ehrlichiosis. Soluble interleukin-2-receptor alpha was found to be 2-fold increase of normal. Computed tomography of brain, chest, abdomen and pelvis were completed, negative for malignancy. Patient had rapid resolution of fever, rash, pancytopenia, improvement of mental status and respiratory status, with liberation from the ventilator within 48 hrs of treatment with addition of doxycycline. Serologic studies later returned positive with 160-fold increase in Ehrlichia IgG antibody. Ehrlichia Chaffeensis DNA was detected by PCR in the peripheral blood.
This case highlights the aggressive nature of the rare diagnosis of HLH. Prompt identification of HLH and initiation of empiric antibiotic treatment is crucial to prevent further systemic damage. Tick-borne disease is often overlooked and should highly be considered in patients in endemic regions.
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