RESUMEN
BACKGROUND: Macrophage activation syndrome (MAS) is an acquired form of hemo phagocytic lymphohistiocytosis (HLH) and is usually associated with infections, autoimmune, auto inflammatory syndromes and malignancies. CASE DETAILS: A 14 year old girl presented with sub-acute onset of fever with lymphadenopathy, pancytopenia,high ferritin values and a falling erythrocyte sedimentation rate. She was evaluated with relevant laboratory tests that was suggestive of systemic Lupus erythematosus and associated macrophage activation syndrome She recovered with immunosuppressive therapy and other supportive care. CONCLUSION: There is a need for a high index of suspicion of occult MAS and MAS in patients with systemic lupus erythematosus as it may be an initial presentation. Delay in diagnosis and initiation of treatment can lead to a higher mortality.