Thrombotic thrombocytopenic purpura in a child with systemic lupus erythematosus.

We report a child with thrombotic thrombocytopenic purpura (TTP) secondary to systemic lupus erythematosus. The diagnosis was confirmed by low ADAMTS13 activity (<5%) along with the presence of a low titer inhibitor. Her clinical course was complicated by systemic lupus erythematosus, immunosuppressant therapy, and septic shock. She responded to plasma exchange and ADAMTS13 activity levels recovered. This case illustrates the heterogeneity of TTP and the difficulty of making a diagnosis of TTP. ADAMTS13 activity assay can be useful in the differential diagnosis of diseases with clinical features of thrombotic microangiopathy in pediatric patients. However, treatment needs to be decided carefully case-by-case.