Board Thread:Metal Gear Solid V/@comment-68.207.141.23-20140915183235/@comment-1504072-20140915193715

I don't believe so, as the horn/debris is clearly embedded in the skull in the x-ray images featuring Big Boss. The condition you linked to is a cutaneous condition, meaning it affects the integumentary organ system that encloses the body (skin, hair, nails, and related muscle and glands).