UNMASKING THE STORM: HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS IN SYSTEMIC LUPUS ERYTHEMATOSUS - A CASE SERIES

Background/Aims Hemophagocytic lymphohistiocytosis (HLH), a critical illness of uncontrolled immunological activity and hyperinflammation, manifests as primary/familial or secondary form. Secondary HLH can be of multi-faceted etiology including infections, cancer, autoimmune and immunodeficiencies. HLH in context of systemic lupus erythematosus (SLE) is a rare entity and mirrors the clinical picture of SLE flare, adding to the diagnostic dilemma. Methods Our objective is to consider HLH as a key differential in unidentified autoimmune diseases. We present a trio of cases of undiagnosed SLE manifesting as HLH. Results A 13-year-old male presented with fever, rash, oral ulcers, and jaundice for a month with passage of dark coloured urine for last seven days. On examination, he had generalized lymphadenopathy, erythematous maculopapular rashes, palpable purpura, non-scarring alopecia, and hepatosplenomegaly. The labs revealed pancytopenia (Hb 9.8g/dL, WBC 2000/mm3, Platelets 23000/mm3), deranged creatinine (1.6mg/dL), transaminitis and hyperbilirubinemia, hyper-ferritinemia (2420 mu g/dL), hypertriglyceridemia (280mg/dL), hypofibrinogenemia (142mg/dL), and nephrotic range proteinuria (3.7g/24h). Diagnosis of SLE was confirmed by high titres of antinuclear antibody (ANA) and anti-double stranded DNA (dsDNA) and anti-Smith positivity. Renal biopsy showed class II lupus nephritis and acute tubular necrosis. Bone marrow biopsy revealed hemophagocytosis and the diagnosis of SLE complicated by HLH was made. A 16-year-old girl presented with fever and headache for three weeks, worsening over last ten days with irritable behaviour for one day, and respiratory distress that necessitated endotracheal intubation. The presence of pancytopenia (9.1/1940/41000), transamintis, hyper-ferritinemia (4040 mu g/dL), hypertriglyceridemia (250mg/dL), and low fibrinogen (133mg/dL) in laboratory evaluation raised a compelling suspicion of HLH confirmed by hemophagocytosis on marrow biopsy. Cerebrospinal fluid analysis was unremarkable, however MRI detected features of vasculitis with vasculitic infarcts. Direct Coomb's test was positive. Autoimmune profiling unveiled positive results for ANA, anti-dsDNA, and anti-Smith antibodies consistent with SLE. A 21-year-old female presented with fever and arthralgias for two months. Investigations were suggestive of pancytopenia (7/1050/36000), raised ESR (126mm/hr) and CRP (54 mg/dL), elevated ferritin (4320 mu g/dL), lactate dehydrogenase (1068U/L) and triglycerides (439mg/dL). The marrow biopsy was negative for hemophagocytosis while her soluble interleukin - 2 receptor levels were elevated (2740 U/ml). ANA and dsDNA were positive in significant titres, complement levels were low and Coombs test was positive, thereby confirming the primary diagnosis of SLE. All patients received methylprednisolone pulse along with cyclophosphamide in case 1 and IVIG in case 2 and 3, resulting in remarkable improvement. Conclusion With a prevalence of 0.9-4.6%, HLH secondary to SLE is an uncommon entity. The diagnosis of HLH related to SLE is challenging since the symptoms overlap, however findings of hyperferritinemia, hypofibrinogenemia, and hypertriglyceridemia favour HLH over SLE. Once HLH is proven, immunological testing for SLE is warranted to prevent diagnostic delay. Early treatment is needed to combat such a fulminant life-threatening illness.