Síndrome d’activació macrofàgica com a forma de debut d’una artritis idiopàtica juvenil sistèmica

Abstract

Introduction. The macrophage activation syndrome (MAS) is a hemophagocytic lymphohystiocytosis developing in the context of a rheumatologic disease and it is commonly associated to systemic juvenile idiopathic arthritis (sJIA). Case report. A 23-month-old child was admitted with a six-day history of fever, conjunctival hyperemia, rash, and hand and foot edema. An infectious disease process was first ruled out, and Kawasaki disease was then suspected. The echocardiogram did not show abnormalities, and intravenous gamma globulin and ibuprofen were administered, without clinical response. The autoantibody screening was negative. The patient progressively developed arthralgias, hepatosplenomegaly and pleural effusion. Blood tests showed anemia, thrombocytopenia, leukocytosis, and elevated inflammatory markers. MAS was suspected, and bone marrow aspirate was performed, which showed no signs of hemophagocytosis or malignancy. Treatment with high-dose corticosteroids was started, resulting in improvement of the general condition of the patient, but with persistence of fever, joint pain, leukocytosis, and elevated inflammatory markers. sJIA-associated MAS was suspected, and interleukin-1-receptor antagonist (anakinra) was started, with significant clinical improvement, decrease in inflammatory markers, and resolution of the fever in 48 hours. Comments. MAS is a life-threatening illness that can present as the first sign of sJIA. It is important to know the diagnostic criteria of both entities for early diagnosis. Treatment with corticosteroids and anti-IL-1 is very effective.