Pyelonephritis complicating a multicystic dysplastic kidney

Renal dysplasia describes a heterogeneous group of malformations characterized by abnormal parenchymal development that is caused by anomalous differentiation of metanephric tissue. When a diffusely dysplastic kidney contains cysts, the term "multicystic dysplastic kidney" applies. Primary infections involving multicystic dysplastic kidneys are rare. There has been only one well-documented case in the literature. The patient discussed here is the second such case and the first to show inflammation in the involved atretic ureteral segment, supporting the notion that bacteria may ascend via a ureteral microlumen to affect the kidney.