Is that a real photo of his knuckles? I mean, the MS13 is clearly added on and likely a "decoded" read of the pot leaf, smiley face, cross, and skull tattoos that are clearly in the knuckles (very dubious on that symbolism) but are this even Kilmer's actual knuckles? Or just a random photo of someone else?

Edit: yes, those are his knuckles as you can see pictures of him talking to that senator.

I strongly doubt, based on a quick search, that those are in any way related to a gang. They are evidence of drug culture (gasp!) but I've yet to see any evidence that any gang uses those.

Edit 2: it appears MS13 members literally just get tattoos that say "MS13" and don't attempt to hide it. It's a proof of loyalty thing, apparently.