Fulminant viral myocarditis after rituximab therapy in pediatric nephrotic syndrome

We report a 7-year-old boy with high-degree steroid-dependent idiopathic nephrotic syndrome (SDNS) who went into remission with rituximab (RTX) maintenance therapy. Four months after this patient received his first RTX infusion, there was a progressive and sustained decrease of immunoglobulin (Ig)G and IgM levels. Thirteen months after the initiation of RTX therapy he was in sustained remission without any steroid or oral immunosuppressive therapy; however, B cell depletion was still present. At this time he developed a fulminant myocarditis due to enterovirus. Despite aggressive treatment and the administration of intravenous polyvalent immunoglobulins there was no clinical improvement. He successfully underwent heart transplant surgery. We conclude that B cell depletion with RTX is efficacious in the treatment of paediatric SDNS but that it may be associated with severe infectious complications. Therefore, we recommend a close monitoring of Ig levels in children who have received RTX therapy and a supplementation with intravenous Ig as soon as the Ig levels fall below the lower limit of the normal range.