I agree with exPCM. I forgot this point.
Canada does not have an accredited training in a subspecisalty of pathology. The only two areas accredited by the RCPSC (and hence acceptable by the ACGME) are the anatomical pathology and general pathology. No subspecialties!!
Therefore, your primary training in pathology will be acceptable for licensure, as long as your program is ACGME/RCPSC accredited. However, you don't need your subspecialty to be accredited. Be reminded that MANY subspecialty fellowships in the US are not even accredited by the ACGME.
You can also sit for the American Board of Pathology certification exam in anatomical or clinical pathology BUT NOT ANY OF THE SUBSPECIALTIES OF THE AMERICAN BOARD OF PATHOLOGY such as Dermpath. However, you don't need the Board certification for the licensure.
Again, some States offer the so-called special license for those who do not have the USMLE but have equivalent training. Look for it, otherwise you have to sit for the USMLE.