Someone I work with has a small head, what is this syndrome/illness called?

I work with this guy, and for a little bit, I thought he was a she. He has a very small head in proportion to his body. His voice has a high pitch to it. His hands are larger than normal, and his body looks larger than it should… but not fat. Around his neck, it looks like shrunken skin, or scarred skin.

I don’t want to ask him about it, since it would be one of those things someone would be self conscious about, and I don’t want to offend him. It’s just been a curious thing that I think of each time I see him.

I think that about sums up how to describe him… Does anyone know what this is called?