Objective: We previously reported a case series of acute pancreatitis (AP) and macrophage activation syndrome (MAS) in childhood (cSLE) patients; however, there are no data regarding the comparison of AP and MAS in large populations of cSLE and adult SLE (aSLE).Methods: A study included 362 cSLE and 1830 aSLE patients. MAS was diagnosed according to preliminary diagnostic guidelines and AP according to the presence of abdominal pain or vomiting associated to an increase of pancreatic enzymes and/or pancreatic radiological abnormalities. Demographic data, clinical features, SLEDAI-2K, SLICC/ACR-DI, and treatment were assessed.Results: Age in MAS patients was significantly lower compared with those without this complication [15 (8.8-55) vs. 33.5 (10.2-45.7) years, p = 0.0071. The frequencies of fever (94% vs. 37%, p = 0.001), leucopenia (82% vs. 19%, p = 0.0001), thrombocytopenia (65% vs. 19%, p = 0.013), hypertriglyceridemia (87% vs. 42%, p = 0.037), and hyperferritinemia (93% vs. 37%, p = 0.011) were also more frequently observed in AP patients with MAS compared in AP patients without MAS. Fever and hyperferritinemia concomitantly were more frequent in the former group (86% vs. 12%, p = 0.0015). Higher and significant frequency of AP in cSLE compared to aSLE patients [12/362 (3.3%) vs. 20/1830 (1.1%), p = 0.003], with similar AP duration [22 (6-60) vs. 15 (4-90) days, p = 0.534]. MAS (85% vs. 30%, p = 0.003) and death by MAS complication (31% vs. 0%, p = 0.017) were significantly higher in children compared with aSLE.Conclusions: This study provides novel data demonstrating that MAS occur in the majority of cSLE with AP with a higher mortality compared to aSLE. In addition, we identified in AP patients, a cluster of MAS clinical and laboratorial parameters more associated with this complication. (C) 2016 Elsevier Inc. All rights reserved.