Pressure Atrophy Atrophy of the kidney o Due to hydronephrosis which presents distension and dilation of the renal pelvis and calyces,usually caused by obstruction. o This increased pressure within the renal pelvis and calyces results in renal parenchyma atrophy (renal cortex or medulla). Atrophy due to hydronephrosisPressure Atrophy Atrophy of the kidney Due to hydronephrosis which presents distension and dilation of the renal pelvis and calyces, usually caused by obstruction. This increased pressure within the renal pelvis and calyces results in renal parenchyma atrophy (renal cortex or medulla). Atrophy due to hydronephrosis