Haemophagocytic Lymphohistiocytosis as an Initial Presentation of Undiagnosed Systemic Lupus Erythematosus.

Background: Haemophagocytic lymphohistiocytosis (HLH) is a rare but potentially fatal hyperinflammatory syndrome with multi-organ involvement. It may occur secondary to autoimmune diseases such as systemic lupus erythematosus (SLE). Case description: This report describes an unusual case of a previously healthy 29-year-old female medical student who presented with a one-month history of recurrent fever, fatigue and significant weight loss. Initial laboratory investigations revealed pancytopaenia, hyperferritinaemia and hypertriglyceridaemia. Infectious disease workup was negative. Serological testing demonstrated positive antinuclear antibody and anti-double-stranded DNA antibodies, while bone marrow biopsy confirmed haemophagocytosis. The patient was diagnosed with secondary HLH due to SLE. During treatment in the intensive care unit, the patient developed psychosis manifested by visual hallucinations and mood swings. A diagnosis of neuropsychiatric SLE was confirmed by exclusion of other causes (e.g. steroid therapy) and the presence of non-specific white matter hyperintensities on brain magnetic resonance imaging. Combination therapy with high-dose corticosteroids, intravenous immunoglobulin and rituximab resulted in significant clinical and laboratory improvements within two weeks. Conclusion: This case illustrates how HLH can be the initial manifestation of previously undiagnosed SLE. Hence, clinicians should maintain a high index of suspicion for underlying autoimmune disorders such as SLE when evaluating patients with HLH, as early recognition and appropriate immunosuppressive therapy are crucial for optimal outcomes. LEARNING POINTS: Clinicians should suspect haemophagocytic lymphohistiocytosis in patients with persistent fever and cytopaenias, especially when laboratory findings (e.g. hyperferritinaemia, hypertriglyceridaemia) do not improve with standard treatments.Systemic lupus erythematosus may initially present as secondary haemophagocytic lymphohistiocytosis. Integration of clinical, radiological and immunological data can aid in early differentiation.