Severe Initial Presentation of Systemic Lupus Erythematosus Mimicking Hemophagocytic Lymphohistiocytosis Secondary to Epstein-Barr Virus (EBV): A Case Report.

A Hispanic woman in her fifth decade of life presented to the Emergency Department with severe abdominal pain, dry heaving, fevers, and weight loss for two weeks. She underwent a CT of the abdomen and pelvis, notable for appendiceal thickening, and was diagnosed with subacute appendicitis with regional lymphadenopathy, thought to be reactive. Her fever persisted on empiric antibiotics, and she underwent a total-body CT that showed diffuse lymphadenopathy. She developed pancytopenia, underwent a bone marrow biopsy, and was started on high-dose dexamethasone with concern for hemophagocytic lymphohistiocytosis (HLH). Her symptoms improved on dexamethasone but remained persistent throughout her tapering, and she underwent rheumatological evaluation given her family history of systemic lupus erythematosus (SLE) in her adult daughter. She was found to have positive anti-double-stranded DNA (anti-dsDNA) antibodies, was started on hydroxychloroquine, improved, and was discharged from the hospital with outpatient rheumatology follow-up. Later, her kidney biopsy was positive for lupus nephritis, confirming the diagnosis.