The renal parenchymal junctional line in children: ultrasonic frequency and appearances.

The kidneys of 72 children were examined ultrasonically to determine the frequency of visualisation of the parenchymal junctional line (PJL), its variation with age and its ultrasonic appearances. The PJL was seen in 47 cases, usually on the right side. No statistical variation in the frequency of visualisation with age has been established. The usual appearance is of a thin, echogenic, linear structure running from the renal sinus to the cortex in an antero-superior direction. It is believed to originate from a layer of connective tissue which is trapped when a proportion of kidneys form from the fusion of two metanephric elements. The PJL is a common ultrasonic finding in a normal child's kidney and should never be confused with a pyelonephritic scar.