Max Casella Says He Was on Growth Hormones and Didn't Hit Puberty Until He Was 27: 'Horror Show'

Jamie McCarthy/Getty Images Max Casella

Max Casella is opening up about not experiencing puberty until his late 20s.

The actor, 55, told Page Six that he has pituitary dwarfism and was 27 when he hit puberty.

"I was given testosterone," he told the outlet at Wednesday's premiere for the Paramount+ series Tulsa King, in which Casella stars. "I was on growth hormones; I'm still on those things. My body didn't go through the change by itself."

Explained Casella: "I have a malfunctioning pituitary gland from birth and basically had to jumpstart my puberty by pumping me full of testosterone and growth hormones to get me to grow because it wasn't happening. I was 25, and I hadn't even shaved."

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Being candid about the condition, Casella described it as "a horror show," adding, "I couldn't talk about it. No one understood it. It's like the trans community today talks about body dysmorphia and feeling like, 'I'm in the wrong body,' absolutely my experience. Absolutely. I was a man trapped in a little boy's body throughout most of my 20s until they finally pumped me full of testosterone."

In an exclusive interview published Friday, Casella told PEOPLE how appearing younger than he really was impacted his acting career.

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In his late 20s, the actor found himself struggling to book the kind of roles he had aspired to. "Show business can just step all over your heart," he said matter-of-factly.

"You go out to L.A., get on [a] TV show, get famous and then you're known for this show for a while. I was in my 20s, I was playing kids, prepubescent characters. And then I grew out of that and grew up into manhood, and I had to start all over again, because it wasn't a smooth transition like it is for a lucky few people."

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Casella, who found early momentum in films like 1992's Newsies with Christian Bale and 1996's Sgt. Bilko with Steve Martin, felt at the time it was movie stardom or bust. But in the process, "I got away from all the studying I had done about acting," he admitted.

Now he stars opposite Sylvester Stallone in the new mob drama Tulsa King (premiering Sunday on Paramount+), playing a recovering gangster hiding out in Oklahoma. Casella called the project "the greatest experience of my career" — in part due to the richly developed character he plays.

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In Tulsa King, Casella portrays "a guy who's been running his whole life and pretending to be something he's not," who is forced to face his past when Stallone's mobster suddenly moves to town.

Working with Stallone "was like a dream come true," Casella said. "I had his poster on my wall when I was 10. He was everything you would want him to be."