The small image Ito uploaded appears to show the beginning of a entrance or long hallway. Unforuntately the image itself is quite small and Ito can't/won't upload a high res image so details are hard to distinguish but Twitter users have asked for more information.
Ito stated that it's a concept image he was working on in 2013 and was not part of P.T as he was not involved in that project. He also states that he cannot describe the image as it "contains metathors of the story".
As great as this is to see additional Silent Hill concept ideas from Ito himself, it's sad to see that if this wasn't a part of Silent Hills that it would appear another game was canned before even having a chance to shine. Fingers crossed Konami are taking huge notes about this and are working on something big already.
You can check out a slightly bigger image of the concept art below.