Parmigiano Reggiano cheese with mold is safe to eat if you cut off and remove the actual moldy parts of the cheese.
However if the mold you're referring too is actually the crystalized amino acids which appear like mold then it's very safe to eat the Parmigiano Reggiano Cheese with the crystalized amino acids because it's not really mold.
If the Parmesan Reggiano has mold the Parmesan Reggiano Mold will appear either blue or green in color on the cheese.
If it appears mostly white then the mold is likely just the result of crystalized amino acids on the cheese which is normal and okay to eat.
What appears as mold on fresh on good parmigiano reggiano cheese is actually not mold at all.
The spots that appear on parmigiano reggiano cheese that looks like mold is actually crystalized amino acids.
The surface of the parmigiano reggiano cheese turns a bit darker when it gets cut and exposed to air making the crystals easier to see.
Actual cheese mold is blue or green.
So if the mold spots look like the below picture on your parmigiano reggiano cheese then it's not actually mold but instead just the harmless crystalized amino acids.
