Ehrlichiosis mimicking acute leukemia

Human monocytic ehrlichiosis is a tickborne disease with a spectrum of presentations ranging from asymptomatic, mild to fatal. Ehrlichiosis can transiently cause white blood cells abnormalities that mimic leukemia/lymphoma and cases have been, on rare occasions, initially mistaken for hematological malignancies. We report a case of Ehrlichia chaffeensis infection suspected to be acute promyelocytic leukemia at presentation, prompting therapy with all-trans-retinoic acid. Physicians should keep tickborne transmitted illnesses on the differential in patients presenting with pancytopenia, especially in endemic areas.