What does it mean on my 9 month old childs chest xray when it says "superimposed infiltrate at right infrahilar region is suspected" & what causes it?

Not deffinitive: I suppose the radiologist saw an area of questionable inflammation superimposed on the heart image. It may not mean anything clinically, or it may be significant. I would ask your child's primary care doctor to clarify the findings. He or she may ask the radiologist to do so.

Usually....: ..It means that there is mucus/congestionin a part of your child's lung. This can be seen with infectious pneumonias or asthma.For a more complete understanding, discuss the "whole" case with your pediatrician.