SHM Converge Scientific Abstract ePoster Gallery-Mimicking Malignancies: Profound Lymphocytosis as a Result of Infectious Mononucleosis

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A 61-year-old woman with hypertension and rheumatoid arthritis treated with Humira presented with tachycardia, tachypnea, altered mental status, fatigue, and a growing submandibular mass. Exam showed diffuse, nonpainful cervical lymphadenopathy and disorientation without focal neurologic deficits. Labs revealed profound leukocytosis with marked lymphocytic predominance, elevated lactate, ferritin, and D-dimer, along with mild anemia and acute kidney injury.<br /><br />Initial imaging showed bulky, centrally necrotic cervical and supraclavicular lymph nodes, and subsequent imaging demonstrated extensive mediastinal, retroperitoneal, pelvic, and inguinal lymphadenopathy concerning for lymphoma. Because of the severity of the presentation, the team considered hematologic malignancy, HLH, atypical infection, and autoimmune disease. However, flow cytometry was negative for a monoclonal process, bone marrow was normocellular, and EBV testing showed positive serologies and very high EBV viral load by PCR.<br /><br />Lymph node biopsy revealed atypical T-cell infiltrates with scattered EBV-positive cells and necrosis, supporting severe Epstein-Barr virus infectious mononucleosis rather than malignancy. Her mental status and symptoms improved during hospitalization, and she was discharged on hospital day six after stopping Humira.<br /><br />This case highlights that EBV infection can rarely produce profound transient lymphocytosis and imaging findings that closely mimic leukemia or lymphoma, especially in immunosuppressed patients. It underscores the importance of maintaining a broad differential diagnosis for severe leukocytosis and avoiding premature anchoring on imaging alone.

Asset Subtitle

Merete Lund

Meta Tag

Author List Adam Kline, Jennifer McEntee, Merete Lund

Category Clinical Vignettes

Concept Epstein-Barr virus infectious mononucleosis

Concept Lymphocytosis

Concept Lymphadenopathy

Concept Hematologic Malignancy

Concept Leukocytosis

Distinguished Non-Finalist

Presenter Organization UNC Internal Medicine Resident

Presenting Author Merete Lund

Track Adult

Keywords

Epstein-Barr virus

infectious mononucleosis

lymphocytosis

lymphadenopathy

immunosuppression

Humira

rheumatoid arthritis

lymphoma mimic

EBV viral load

cervical mass

Epstein-Barr virus infectious mononucleosis

Lymphocytosis

Lymphadenopathy

Hematologic Malignancy

Leukocytosis