Local leukocyte proliferation as a target for cyclophosphamide in the treatment of Henoch‐Schönlein purpura nephritis grade VI

Henoch‐Schönlein purpura nephritis (HSPN) is one of the most common types of chronic glomerulonephritis in children; however, there have been few reports on the pathogenesis and management of grade VI HSPN. We present the case of a 6‐year‐old boy with grade VI HSPN accompanied by severe nephrotic syndrome and hypocomplementaemia. Immunohistological studies revealed profound glomerular accumulation of CD45‐ and CD68‐positive inflammatory cells. Moreover, some cells expressed the proliferating marker proliferating cell nuclear antigen. His proteinuria and general oedema persisted despite repeated high‐dose steroid therapy; however, these clinical symptoms immediately improved after beginning treatment with cyclophosphamide (CyP). Grade VI HSPN was successfully treated with steroids and immunosuppressants. Among immunosuppressive drugs, CyP was considered the most effective.