Ehrlichia-Induced Hemophagocytic Lymphohistiocytosis: A Case Series and Review of Literature.

Hemophagocytic lymphohistiocytosis (HLH) is a rare potentially fatal syndrome characterized by an uncontrolled hyperinflammatory response. The secondary form of HLH is usually triggered by a causative agent. Ehrlichia chaffeensis is a rare trigger of secondary HLH. We present a case series of five adolescents and adults diagnosed with Ehrlichia-induced HLH and we discuss their clinical and laboratory findings. We also review the literature for similar cases. Between October 2003 and June 2014, we identified 76 cases of HLH in adolescents and adults, 5 of which were induced by Ehrlichia. All 5 patients had fever, cytopenias, hypertriglyceridemia, and high ferritin. Hyperferritinemia was striking with a median admission ferritin of 47,290 μg/L (range: 2,863-85,517). In addition to the positive Ehrlichia PCR testing on peripheral blood of all patients, two patients with neurologic symptoms tested positive for E. chaffeensis in CSF specimens. Early treatment with doxycycline was effective. After a median follow up of 7.3 months, all patients were alive and none had recurrence of HLH. Clinicians should consider E. chaffeensis as a potential trigger for HLH especially in areas with tick activity. Prompt diagnosis and treatment with doxycycline are required for a better outcome.