AB0773 PATTERN OF MACROPHAGE ACTIVATION SYNDROME IN RHEUMATIC DISEASES

Background: Macrophage activation syndrome (MAS) is a rare, potentially fatal condition complicating autoimmune diseases, as their initial manifestation or during its course. Objectives: To describe the pattern of MAS and its salient features in patients with rheumatic diseases. Methods: A retrospective observational study was conducted in 16 patients diagnosed with MAS, due to rheumatic diseases in Department of Rheumatology, SRIHER, Chennai from January 2018-December 2020. Results: The primary diseases were Systemic Lupus Erythematosus(SLE) in 75%(n=12),Adult Onset Still Disease(AOSD) in18.7%(n=3) and Kikuchi Disease in 6.25%(n=1). 50%(n=8) presented with MAS as the initial manifestation.Others had a known rheumatic disease with an average duration of 6.5 years.Occult MAS was seen in 25%(n=4). The most frequent clinical features were unremitting fever(n=15) and splenomegaly(n=15).All had hyperferritinemia-mean of 2971.10 ng/mL(531-12536).Sub group analysis showed significant hypofibrinogenemia(129.8 vs 200.62 mg/dl) in patients presenting with MAS as their initial manifestation.Transaminitis(666/252.5 vs 243/217.62 U/L), hypertriglyceridemia(316 vs 275.8 mg/dl), high LDH(2490 vs 938.75) were more severe in this group, but not significant.All with SLE had increased disease activity, with 50%(n=8) having SLEDAI 2K of ≥15.Bone marrow aspiration showed haemophagocytes in 81.25%(n=13).H score of >169 was seen in 93.75%(n=15). Infection was the commonest trigger for MAS(n=9)-bacterial(n=5), viral(n=4), fungal(n=1) and mycobacterial(n=2),followed by parturition(n=1).All patients were managed with pulse steroids followed by intravenous cyclophosphamide(n=8), rituximab(n=2), mycophenolate mofetil(n=2) in SLE, tocilizumab(n=2) and etoposide(n=1) in AOSD.Mortality rate was 18.75%(n=3). Conclusion: Spectrum of MAS in rheumatic diseases could be occult, associated with infection,high disease activity,or lead to mortality. High index of clinical suspicion is required, due to overlap of features like fever, cytopenias and organomegaly in MAS & SLE.Hyperferritinemia, high LDH, & transaminitis could aid in differentiating & early diagnosis. New criteria for rheumatic diseases,including these parameters are needed, especially in resource-limited settings where sIL-2Rα & NK cell activity tests are not feasible. References: [1]Stuart J.Carter et al. Macrophage activation syndrome in adults:Recent advances in pathophysiology, diagnosis and treatment. Rheumatology 2019;58;5-17 [2]Ai-Chun Liu et al.Macrophage activation syndrome in systemic lupus erythematosus:a multicentre,case-control study in China.Clin Rheumatol 2017. Disclosure of Interests: None declared