Fever, pancytopenia, and elevated D-dimer in a 95-year-old woman with ehrlichiosis: a case report.

Background: Pancytopenia, fever, and elevated D-dimer are significant clinical findings. The differential diagnosis includes hematological malignancies, severe coronavirus disease 2019 (COVID-19), tick-borne illnesses, and other etiologies.
Case Presentation: We report the case of a 95-year-old woman who presented with high fever (103.6 °F), pancytopenia, and markedly elevated D-dimer (32.21 mg/L; reference range ≤ 0.95 mg/L) in late-autumn during the COVID-19 pandemic at a large academic institution. After remaining persistently febrile, a peripheral blood smear was ordered and revealed parasites consistent with Ehrlichia spp. Doxycycline monotherapy led to symptomatic improvement and resolution of her pancytopenia. During her hospital stay, a computed tomography angiogram of the chest revealed pulmonary emboli, and esophagogastroduodenoscopy uncovered arteriovenous malformations. After appropriate treatment, she was discharged on hospital day 7 and has since done well.
Conclusions: Overall, our case offers a dramatic, unexpected presentation of ehrlichiosis in a nonagenarian. To our knowledge, this is the first report of concurrent ehrlichiosis and pulmonary embolus.