Ehrlichiosis infection in a 5-year-old boy with neutropenia, anemia, thrombocytopenia, and hepatosplenomegaly.

Ehrlichiosis should be considered in the differential diagnosis of any patient with recent fever, pancytopenia, hepatosplenomegaly, and history of tick exposure. We present a previously healthy 5-year-old boy who was referred to the Hematology-Oncology Clinic to consider a bone marrow etiologic process after his pediatrician discovered progressive neutropenia, anemia, thrombocytopenia, and hepatosplenomegaly accompanied by 2 days of fever. Bone marrow aspirate and biopsy were nonrevealing. Because of the history of a recent tick bite, a diagnosis of ehrlichiosis infection was considered and ultimately confirmed by IgG-specific serum testing. The patient's fever was treated symptomatically with acetaminophen, and symptoms resolved on their own without intervention. Ehrlichiosis is a tick-borne infection that occurs throughout the spring and summer, often causing findings that mimic a malignancy or serious hematologic disorder. The diagnosis should be considered in any person living in tick-infested areas and can be confirmed by polymerase chain reaction or serum antibody titers. Treatment with doxycycline can lead to rapid clinical improvement if the diagnosis is made early.