SHM Converge Scientific Abstract ePoster Gallery-Fever, Ferritin and Ticked Off Histiocytes - A Case of Anaplasmosis Induced Hemophagocytic Lymphohistiocytosis

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A woman in her 40s presented in summer with 2 weeks of headache, neck pain, nausea, poor appetite, confusion, and lethargy. She was febrile, hypotensive, and had thrombocytopenia, acute kidney and liver injury, and later imaging showed hepatosplenomegaly. Because of persistent fever and worsening clinical status, clinicians calculated an H-score of 224, indicating a 90% likelihood of hemophagocytic lymphohistiocytosis (HLH). Given her Midwestern residence, dog exposure, and tick-borne risk, doxycycline was started empirically for possible anaplasmosis. <br /><br />Despite this, she remained febrile and altered on hospital day 5, prompting bone marrow biopsy and initiation of dexamethasone for suspected secondary HLH. By hospital day 6, both her fever and mental status improved markedly. Anaplasma phagocytophilum PCR later returned positive, confirming anaplasmosis as the trigger for secondary HLH. She was discharged on day 11 with resolution of fever and confusion, completing doxycycline for 10 days and dexamethasone with taper. <br /><br />The case highlights two key points: first, human granulocytic anaplasmosis can present severely with cytopenias, transaminitis, renal dysfunction, and fever, and should improve within 24–48 hours of doxycycline; if not, further evaluation is needed. Second, HLH is a dangerous hyperinflammatory syndrome that can be secondary to infection, including tick-borne disease, and may require immunosuppressive treatment after the underlying cause is addressed.

Asset Subtitle

Philip P. Huang

Meta Tag

Author List Philip P. Huang, Philip Y. Chang

Category Clinical Vignettes

Concept Human Granulocytic Anaplasmosis

Concept Secondary hemophagocytic lymphohistiocytosis

Concept Doxycycline

Concept H-score

Concept Tick-Borne Infection

Distinguished Non-Finalist

Presenter Organization The Ohio State University Wexner Medical Center

Presenting Author Philip P. Huang

Track Adult

Keywords

anaplasmosis

hemophagocytic lymphohistiocytosis

HLH

doxycycline

tick-borne disease

Anaplasma phagocytophilum

fever

thrombocytopenia

hepatosplenomegaly

dexamethasone

Human Granulocytic Anaplasmosis

Secondary hemophagocytic lymphohistiocytosis

Doxycycline

H-score

Tick-Borne Infection