This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Macrophage activation syndrome is most commonly-1 seen in association with? 
Select and explain. 
A. Systemic sclerosis, B. Sweet's syndrome, C. SLE, D. Juvenile Rheumatoid Ahritis
D: Juvenile Rheumatoid Ahritis
Answer: D: Juvenile Rheumatoid Ahritis 
Explanation: Answer is D (Juvenile Rheumatoid Ahritis): Macrophage Activation Syndrome is most commonly seen in association with Systemic Onset Juvenile Idiopathic Ahritides (Earlier termed JRA) and adult-onset Still's Disease. Amongst other autoimnnine diseases, MAS has also been repoed in patients with Juvenile SLE and Kawasaki Disease (Rare causes). Macrophage activation syndrome (MAS) is a life threatening complication of rheumatic diseases thought to be caused by the uncontrolled activation and proliferation of T lymphocytes and well-differentiated macrophages leading to widespread hemophagocytosis and cytokine overproduction. For unknown reasons, occurs much more frequently in systemic juvenile idiopathic ahritis (S-JIA) and in its adult equivalent, adult-onset Still disease. MAS has also been repoed in other systemic inflammatory disorders, including SLE and Kawasaki disease. The main clinical features of MAS include a high unremitting fever, hepatosplenomegaly, lymphadenopathy, bleeding, rash and central nervous system manifestations. Hyperferritinemia is an impoant laboratory hallmark of Macrophage Activation Syndrome MAS is regarded as a an acquired cause of Haemophagocytic Lymphohistiocytosis (HLH)