An unusual cause of severe persistent neutropenia in a child with nephrotic syndrome.

A 5-year-old boy presented with neutropenia 9 weeks following the administration of rituximab for management of his steroid-dependent nephrotic syndrome. Extensive investigations failed to identify any underlying cause. In keeping with adult reports, rituximab was thought to be the likely cause for this 'late-onset' neutropenia (LOP). He was treated successfully with granulocyte-colony-stimulating factor. Patients treated with rituximab need to be carefully monitored for LOP.