Sirolimus lowers myeloperoxidase and p-ANCA titers in a pediatric patient before kidney transplantation.

We report the case of a child with microscopic polyangiitis (myeloperoxidase-antineutrophil cytoplasmic antibody [p-ANCA]-positive vasculitis) whose disease progressed to end-stage renal failure, in whom sirolimus contributed to normalization of myeloperoxidase and ANCA titers. The disease course, various therapies, and outcome are discussed, as is the rationale for using sirolimus.