MACROPHAGE ACTIVATION SYNDROME IN SYSTEMIC LUPUS ERYTHEMATOSUS: REPORT OF 8 CASES

PV202 / #141 Poster Topic: AS23 - SLE-Diagnosis, Manifestations, & Outcomes Background/Purpose Systemic lupus erythematosus (SLE) is a complex autoimmune disease that is characterized by various clinical and biological manifestations. Among its rare but critical presentations, macrophage activation syndrome (MAS) is a severe complication involving the dysregulated activation of cytotoxic T lymphocytes and NK cells, leading to systemic inflammation and multiple organ damage. MAS is a secondary form of hemophagocytic lymphohistiocytosis (HLH). Diagnosis of MAS poses a real challenge, as its clinical manifestations closely resemble those of active SLE. We present a series of cases aimed at detailing the distinctive clinical features of MAS in SLE. Methods This was a retrospective and descriptive study involving 8 cases collected from the internal medicine department over a period of 14 years, from January 2010 to May 2024. The diagnosis of systemic lupus erythematosus was established according to the SLICC or ACR/EULAR 2019 criteria, and patients presented with macrophage activation syndrome (MAS) according to the HLH 2004 criteria. Results Eight patients were included in the study. The average age of the patients was 26 years (range, 17-42 years). There were 7 women and 1 man, resulting in a sex ratio of 7/1. MAS was the initial manifestation of lupus in half of the patients (4 women), while it occurred after the diagnosis of lupus in the other 4 patients. A triggering factor was identified in all patients (infection in 3 patients, pregnancy in 3 patients, and a stressful event in the other 2). Lupus was severe in all the patients. The systemic lupus erythematosus disease activity index (SLEDAI) was calculated for all 8 patients, with an average score of 61.38, a standard deviation of 19.29, a median of 60.5, and a range from 32 to 88. Hematological involvement was observed in 87.5% of the patients (7 cases), cutaneous involvement in 62.5% (5 cases), articular involvement in 50% (4 cases), severe renal involvement in 37.5% (3 cases), serositis in 25% (2 cases), and pancreatitis in 12.5% (1 case). Biologically, pancytopenia was found in 6 patients (75%), and bicytopenia was found in the other 2 patients. Lymphopenia and hyperferritinemia were constant in all patients, with an average lymphocyte count of 680 cells/mm³ and average ferritin level of 4786 ng/mL, ranging from 800 to 11816 ng/mL. Hypofibrinogenemia was observed in 5 patients, with an average fibrinogen level of approximately 1.19 g/L, ranging from 0.3 g/L to 1.5 g/L. Hypertriglyceridemia was noted in 4 patients, with an average of approximately 4.865 g/L, ranging from 3.60 g/L to 6.42 g/L. The complement levels C3, C4, and CH50 were severely reduced in all patients. Antinuclear antibodies were more than 1/80 in all patients, and anti-DNA antibodies were positive in 75% of the patients. All patients received intravenous bolus corticosteroid therapy, antibiotic treatment in 3 patients, and immunosuppressants in 4 patients (2 patients received cyclophosphamide and 2 received mycophenolate mofetil). The outcome was favorable in 75% of the cases, with death recorded in 25%. Conclusions Macrophage activation syndrome is a severe and potentially fatal complication of systemic lupus erythematosus that requires heightened vigilance for early diagnosis and prompt management. Our study revealed that MAS is often triggered by infection, pregnancy, and stress. The clinical manifestations of MAS frequently overlap with those of active SLE, complicating diagnosis. This study highlights the necessity for early detection and appropriate therapeutic interventions to effectively manage MAS in SLE patients.

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