Hi,
CoronaSkinMtl produces weird artifacts when you render geometry, Hair&Fur and lights that produce strong back scatter effects. The hair object needs to be close to the object that uses CoronaSkinMTL. This usually happens in the ears of human characters. I have not found any workarounds to avoid the bug.
Example file rendered with digital Emily model and standard 3dsmax hair and fur object.
I'm using 3dsmax 2017 Corona 6 hotfix 1.
Thanks!