Dress Pants for Tall Thin Men

I was sent a request from Marianne who is trying to find some dress pants for her tall, thin teenager. He is 6'5" and has a 32" waist and 38" inseam.

One option is to purchase a pair of custom made dress pants from Indochino.com. They are known for their custom made suits, but also sell dress pants. You just enter your measurements and choose the style and fabric you love. It's an easy ordering process.
Although not as dressy, Dickies sells pants for tall thin men. They come unhemmed with a 39" inseam length. You could take them to your local tailor to hem them for you.
I hope this helps. :)