1. Macrophage Activation Syndromein a Child withSystemic Juvenile Rheumatoid ArthritisMina Hur, M.D., Young Chul Kim, M.D., Kyu Man Lee, M. D., and Kwang Nam Kim, M.D.* Departments of Laboratory Medicine and Pediatrics*, Hallym University College of Medicine, Seoul, Korea

• Macrophage activation syndrome (MAS) is a severe and potentially life-

threatening complication of rheumatic disorders in children, especially those with systemic juvenile rheumatoid arthritis (S-JRA).

MAS is characterized by serious liver disease, hematologic abnormalities, coagulopathy, and neurologic involvement. Laboratory hallmarks are anemia, thrombocytopenia, & leukopenia in various combinations, evidence of disseminated intravascular coagulation (DIC), hypertriglyceridemia, increased LDH, and hemophagocytosis in bone marrow.

We describe a 13-month-old boy in whom MAS developed as a complication of S-JRA.

He suffered from fever and generalized rash followed by multiple joints swelling for four months before admission. Physical examination revealed cervical lymphadenopathy and hepatosplenomegaly. Laboratory findings were: abnormal liver enzymes, increased triglyceride and ferritin levels, coagulopathies resembling DIC, anemia, and thrombocytopenia (Table 1).

Bone marrow (BM) aspiration smear was diluted with no marrow particle giving no diagnostic information. In BM biopsy, estimated cellularity was about 90%, which was normocellular for age-related value. Granulocytic and megakaryocytic hyperplasia were prominent with suppressed erythropoiesis. Benign-appearing histiocytes were increased and diffusely distributed with hemophagocytic features. Presence of histiocytes was confirmed with positivity of CD68 stain (Fig. 1).

Clinical and laboratory improvement were observed during hospital courses with corticosteroid and cyclosporine therapy (Fig. 2 & 3).

Immunologic mechanisms causing MAS are still unclear. It is thought, however, that T- or NK cell dysfunction leads to macrophage activation and increased levels of many cytokines (specifically, tumor necrosis factor alpha and interferon gamma) released by macrophage or T-lymphoid cells initiate systemic hemophagocytosis.

This is the third case of MAS associated with S-JRA in Koreans, and the first one, in which histiocytic hyperplasia was proven in bone marrow.

INTRODUCTION CASE REPORT DISCUSSION Fig.1.(a) Bone marrow biopsy section illustrates hypercellular marrow with granulocytic and megakaryocytic hyperplasia (H & E stain,200).(b) Histiocytic hyperplasia is prominently observed (CD 68 stain,200).