Macrophage activation syndrome in Still's disease: analysis of clinical characteristics and survival in paediatric and adult patients.

Macrophage activation syndrome (MAS) is a reactive form of hemophagocytic lymphohistiocytosis, complicating Still's disease, both in paediatric and adult patients. In this work, we aimed to investigate clinical picture and outcome of Still's disease patients developing MAS. We performed a retrospective analysis of patients, both paediatrics and adults, affected by Still's disease attending our department. During the follow-up, each patient was investigated for MAS occurrence and possible predictors, clinical and laboratory factors, were analysed. We evaluated 50 patients affected by Still's disease, 21 paediatric and 29 adult patients. Ten patients experienced MAS (five adult and five paediatric patients) and its development significantly reduced the survival rate when compared with patients without this complication (p < 0.0001). The analysis of possible predictors showed that high-value systemic score (p = 0.03) and high levels of serum ferritin (p = 0.002) were independently associated with an increased likelihood of MAS. MAS occurrence significantly reduced survival rate in both paediatric and adult patients affected by Still's disease. The high levels of serum ferritin and an elevated systemic score, at the time of diagnosis, were significantly associated with MAS.