Fatal Cytokine Collision: HLH–AIHA in Advanced AIDS—Case Report and Literature Review

<b>Background and Clinical Significance</b>: Hemophagocytic lymphohistiocytosis (HLH) and autoimmune hemolytic anemia (AIHA) are both life-threatening hematologic syndromes that rarely present together outside of malignancy. Advanced acquired immunodeficiency syndrome (AIDS) creates a milieu of profound immune dysregulation and hyperinflammation, predisposing patients to atypical overlaps of these disorders. <b>Case Presentation</b>: A 30-year-old woman with poorly controlled AIDS presented with three weeks of jaundice, fever, and fatigue. Initial labs revealed pancytopenia, hyperbilirubinemia, and elevated ferritin level. Direct anti-globulin testing confirmed warm AIHA (IgG⁺/C3d⁺) with transient cold agglutinins. Despite intravenous immunoglobulin (IVIG), rituximab, and transfusions, she developed hepatosplenomegaly, extreme hyperferritinemia, and sIL-2R > 10,000 pg/mL, meeting HLH-2004 criteria. Bone marrow biopsy excluded malignancy; further work-up revealed Epstein-Barr virus (EBV) viremia and cytomegalovirus (CMV) reactivation. Dexamethasone plus reduced-dose etoposide transiently reduced soluble interleukin-2 receptor (sIL-2R) but precipitated profound pancytopenia, Acute respiratory distress syndrome (ARDS) from CMV/parainfluenza pneumonia, bilateral deep vein thrombosis (DVT), and an ST-elevation myocardial infarction (STEMI). She ultimately died of hemorrhagic shock after anticoagulation despite maximal supportive measures. <b>Conclusions</b>: This case underscores the diagnostic challenges of HLH-AIHA overlap in AIDS, where cytopenias and hyperferritinemia mask the underlying cytokine storm. Pathogenesis likely involved IL-6/IFN-γ overproduction, impaired cytotoxic T-cell function, and molecular mimicry. While etoposide remains a cornerstone of HLH therapy, its myelotoxicity proved catastrophic in this immunocompromised host, highlighting the urgent need for cytokine-targeted agents to mitigate treatment-related mortality.