Board Thread:Metal Gear Solid V/@comment-68.207.141.23-20140915183235/@comment-25366375-20140921060030

68.207.141.23 wrote: Cutaneous horns aren't exactly natural. And that shrapnel would have to hit pretty far back in the brain to cause hallucinations like that.

I'm rather convinced the image of the diamond shoved in Big Boss' skull was symbolism.

And as for the scars, combat can do that to you. Especially when it's how you make a living. They do occur with exposure to radiation, and we know that Big Boss has suffered from radiation exposure in the past (see: sterility), but ultimately Big Boss' horn appears to be a separate object than his head, not an extension as a result of a tumor.

That said, I could be wrong on this one. Your theory would suggest why Big Boss falls in to the coma with no horn and wakes up with one. My only beef with that, is that surely the doctors would want to remove it before it got to that stage if indeed it were a cutaneous horn. However, perhaps they didn't want to go digging around in his skull considering he was in a coma. I must admit I was pretty dismissive of this idea at first, but upon consideration it certainly adds up.

The only question left is why Kojima chose a cutaneous horn, if this is true.