Artritis idiopática juvenil de inicio sistémico y síndrome de activación macrofágica / Juvenile idiopathic arthritis of sistemic beginning and syndrome of macrophage activation

The macrophage activation syndrome (MAS) i a rare pediatric condition characterized by enhanced activation of the macrophage and T-cell system, with increased liberation of T-cell cytokines. Clinically it resembles a multiorgan failure syndrome of infectious etiology. There is still some debate as to the nomenclature of this syndrome, hemato-oncologists usually classify this syndrome as a histiocytic disorder, while rheumatologists define it as MAS. We review a patient in which MAS was diagnosed during the early stages of the disease. The patient had juvenile idiopathic arthritis (systemic presentation).