Can you get to blocked-in areas?

I keep running into areas where I see a chest in a section of the room that seems completely walled-off. Is there any way to get to these, or is that just the randomly generated dungeon being a tease?

I had to splice two screenshots together to show an example of what I'm talking about:

Is there any way to get in there?

Many of these blocked in areas, including this one, have a small hidden passage where a character with dwarfism can get inside. The hidden passages are darker than the rest of the walls. In this particular case, the top square of the left wall of the box is the secret passage, I believe.

To complete the first answer, there's many rooms with this kind of hidden paths. Some rooms have treasure at the top or bottom of the screen and can be accessed through those kind of path, even in normal size.

Here is a better example of dwarf size path, where you can clearly see the difference of colour:

Edit: And here's another example with hidden chest. You can see that the access is possible in normal size (and I guess in giant too, never has the opportunity to test yet):

Click for view it in full size