Tristan has lived more of his life without a butt than he has with one.
In this clip from tonight's all-new Botched, Tristan recounts dealing with the cancerous tumor that left him butt-less.
And it's a case unlike Dr. Terry Dubrow and Dr. Paul Nassif have ever seen. "Oh my God, the butt's gone!" a shocked Dr. Nassif says after looking at pictures of Tristan's butt.
It all started when Tristan was just eight years old.
"At age eight, I basically lost the nerves, like the mobility in my leg. I basically turned into a flamingo," Tristan explains. "I had no control, I instantly lost the nerves and it just stayed like that."
"Nobody knew that it was a tumor that was growing inside his pelvic area," Tristan's mom adds.
It wasn't until Tristan had been to several doctors that he was diagnosed with Ewing's sarcoma, an aggressive cancer that typically occurs in young children.
"Ewing's sarcoma is a particularly malignant type of bone tumor that can occur throughout the body. Unfortunately, even with modern surgery and chemotherapy techniques, the survival rate can be very low," Dr. Dubrow reveals.
Hear about Tristan's battle with cancer in the clip above.