en Pediatric Hematology & Oncology Pediatric Hematology & Oncology گزارش مورد Case report Macrophage activation syndrome (MAS) is a rare feature of rheumatic disorders in children and adolescence and its presentation as the first symptom of rheumatic disorders is very infrequent.<br> A 9-year-old girl, in whom MAS developed, was admitted to our Hospital in Tehran, Iran. She suffered from high grade fever and rash followed by multiple joint swelling months afterwards. Bone marrow aspiration and biopsy showed normocellular marrow with a cellularity of 90%. Benign-looking macrophages were remarkably increased; many of them showed hemophagocytic features. According to the presentation of long-standing fever and observation of &ldquo;hemophagocytic macrophage&rdquo; in bone marrow, MAS was diagnosed for the patient. Additionally, due to recurrent joint swelling in following months, she was diagnosed to be affected by &ldquo;Juvenile Idiopathic Arhtritis&rdquo; complicated by MAS.<br> MAS is a rare complication of rheumatic disorders which should be considered as the first presentation of rheumatic disorders in children specifically in those presenting with high fever, hepatosplenomegaly, lymphadenopathy and severe cytopenia.&nbsp; Macrophage activation syndrome, Juvenile idiopathic arthritis, Hemophagocytic macrophage, First presentation 93 96 http://ijbc.ir/browse.php?a_code=A-10-247-3&slc_lang=en&sid=1 Hassan Abolghasemi حسن ابوالقاسمی h.abolghasemi.ha@gmail.com 10031947532846003875 10031947532846003875 No Pediatric Congenital Hematologic Disorders Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Pediatric Congenital Hematologic Disorders Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Ira Ehsan Shahverdi احسان شه وردی shahverdi_ehsan@yahoo.com 10031947532846003876 10031947532846003876 Yes Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran - Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran Reyhaneh Niknam 10031947532846003879 10031947532846003879 No Fatemeh Beiraghdar فاطمه بیرقدار esn.sh1387@yahoo.com 10031947532846003877 10031947532846003877 No Department of Pediatrics, Baqiyatallah University of Medical Sciences, Tehran, Iran - Department of Pediatrics, Baqiyatallah University of Medical Sciences, Tehran, Iran Shirin Afkhami Fard شیرین افخمی Shirin_afkhamifard@yahoo.com 10031947532846003878 10031947532846003878 No Mashhad Azad University of Medical Sciences, Mashhad, Iran - Mashhad Azad University of Medical Sciences, Mashhad, Iran