儿童长时间发烧可能是由多种原因引起的，包括感染性、自身免疫性、恶性或遗传性病因。在我们的报告中，我们介绍了一名先前健康的三岁女性的病例，她因系统性幼年关节炎 (sJIA) 并发症而被诊断患有巨噬细胞活化综合征 (MAS)。 MAS 被认为是噬血细胞性淋巴组织细胞增多症 (HLH) 的次要亚型，HLH 是一组罕见且危及生命的综合征，其特征是免疫系统过度刺激，导致全身炎症。通过我们的案例，我们希望提高人们对这一不常见疾病的认识，并讨论区分其亚型的重要性。虽然 HLH 和 MAS 具有相似的临床表现，但各自的治疗方案不同。此外，应该进行进一步的研究，以制定基于证据的标准化标准和治疗指南，以便正确管理这些患者。版权所有 © 2023，Cortes 等人。

A prolonged fever in a child can be due to a range of causes including infectious, autoimmune, malignant, or genetic in etiology. In our report, we present the case of a previously healthy three-year-old female diagnosed with macrophage activation syndrome (MAS) due to complications of systemic juvenile arthritis (sJIA). MAS is considered a secondary subtype of hemophagocytic lymphohistiocytosis (HLH), a rare and life-threatening group of syndromes characterized by overstimulation of the immune system leading to systemic inflammation. Through our case, we wanted to bring awareness to this uncommon group of diseases as well as discuss the importance of differentiating between its subtypes. While HLH and MAS have similar clinical presentations, the treatment regimen for each is distinct. Moreover, further research should be conducted to create standardized criteria and treatment guidelines that are evidence-based in order to properly manage these patients.Copyright © 2023, Cortes et al.