Pediatric Castleman disease (CD) is an uncommon and poorly understood disorder of the lymph nodes. Renal failure has not been described in pediatric multicentric CD (MCD). We report four cases, who presented with polyadenopathy, organomegaly, edema and fluid accumulations, high blood pressure, and acute renal failure. In all cases, renal biopsy confirmed diffuse thrombotic microangiopathy. Definitive diagnosis of MCD was made by a biopsy of an affected lymph node located by computer tomography before initiation of corticosteroid therapy. Treatment of CD with corticosteroid therapy and rituximab was rapidly effective without relapse to date.