Close relationship between systemic lupus erythematosus and thrombotic thrombocytopenic purpura in childhood

Objective. To determine the association between childhood-onset thrombotic thrombocytopenic purpura (TTP) and systemic lupus erythematosus (SLE), Methods. The charts of all 5 patients diagnosed with idiopathic TTP at the Hospital for Sick Children (HSC) in Toronto from 1975 to 1998, and all case s of childhood-onset TTP (ages 6-20 years) reported in the literature over the same period were reviewed. Fourteen of the 44 patients identified in th e literature were excluded from the analysis for lack of clinical and labor atory information. The remaining 35 patients were grouped into either an SL E/TTP group of a TTP only group, according to the presence or absence of th e American College of Rheumatology (ACR) classification criteria for SLE, T he groups were compared for differences in clinical or laboratory features. Results, The clinical presentation and initial disease course of pediatric patients with TTP were similar to those observed in adults. Of the 35 patie nts with childhood-onset TTP-included in this review, 9 (26%) fulfilled gre ater than or equal to 4 ACR criteria for SLE and 8 (23%) were found to have incipient SLE. Of the 5 patients initially diagnosed with idiopathic TTP a t the HSC, 3 were diagnosed with SLE within 3 years, and the other 2 patien ts fulfilled 3 ACR classification criteria for SLE within 3 years of diseas e onset. The clinical syndrome of pediatric TTP presenting with proteinuria , especially with high-grade proteinuria, was significantly associated with the development or coexistence of childhood-onset SLE. Conclusion. TTP in childhood is a rare, but life-threatening, disease. Unli ke in adults, TTP in childhood is commonly associated with SLE, High-grade proteinuria at diagnosis of TTP is the best predictor for the presence or s ubsequent development of SLE.