I agree with varnish roan. In Appaloosas varnish roan is a distinct genetic pattern similar to other appaloosa exclusive colors like leopard etc- it's part of the leopard gene complex. It differs from other breeds and is not a TRUE roan. They loose the spotting and dark areas more and more as they age, but do stay dark around immediate bony areas such as the knees, fetlocks, cheekbones and head etc. It looks to me like this horse also has a blanket extending over the withers, it just blends in to the varnish roan.
This is my 28 year old Varnish Roan gelding Royal P6110017.jpg