[Macrophage activation syndrome in a young patient with polymyositis].

Haemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS) is a life-threatening condition characterised by systemic hyperinflammation and is often triggered by infections, malignancies, or autoimmune disease. The HScore is a diagnostic tool used to estimate the likelihood of HLH/MAS based on clinical, biochemical, and histological findings. This case describes a patient with polymyositis developing MAS, indicated by an HScore of 219. He was treated with IV anakinra, steroids, and immunoglobulin, leading to significant improvement. This case emphasises the importance of early MAS recognition and timely intervention in critical conditions.