(649) Macrophage Activation Syndrome Induced by Anaplasmosis: Treated by Adjuvant Dexamethasone

Introduction: This is a case report of a 72-year-old female patient presenting with severe systemic illness secondary to Anaplasma phagocytophilum infection, leading to macrophage activation syndrome (MAS) and multi-organ dysfunction. A short course of dexamethasone in addition to Doxycycline was effective in terminating the inflammatory cascade with good clinical recovery.

Description: A 72-year-old woman with no significant past medical history with a history of tick bite was admitted to the ICU for septic shock and intubated due to altered mental status. Laboratory tests revealed worsening liver function tests (LFTs), elevated serum creatinine, and an abnormal coagulation profile, alongside thrombocytopenia. A peripheral blood smear showed Howell-Jolly bodies and evidence of Anaplasma species, with no schistocytes observed. Given the presence of altered LFTs, bicytopenia, abnormal coagulation profile, and escalating vasopressor requirements, secondary hemophagocytosis or macrophage activation syndrome was strongly suspected. After administering 10 mg/m2 (23 mg) IV dexamethasone, there was a significant reduction in vasopressor needs within four hours. The norepinephrine infusion was discontinued within 24 hours, and ferritin levels decreased to 6415.4 ng/mL. Dexamethasone was continued for an additional two days at 10 mg and 8 mg, and organ dysfunction indices showed significant improvement. The patient was successfully extubated on day 8 of intubation with good clinical recovery.

Discussion: Anaplasmosis can lead to life-threatening complications such as macrophage activation syndrome, necessitating prompt recognition and aggressive treatment. Abnormal LFTs, coagulation profile and bi-cytopenia in a patient with sepsis like presentation should strongly lead to a suspicion for macrophage activation syndrome. Ferritin, triglycerides and Il-2 levels should be obtained. Short duration of steroids should be considered even for macrophage activation syndrome secondary to infection if antibiotic therapy alone is not sufficient