Sylvester Stallone’s ‘Tulsa King’ co-star Max Casella says he didn't hit puberty until late 20s: 'Horror show'

Max Casella is opening up about his prepubescent years.

The now 55-year-old actor shockingly revealed he didn’t hit puberty until the age of 27.

During an interview with Page Six, he explained he had pituitary dwarfism – a growth hormone deficiency characterized by unusually short height – according to the media outlet.

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"I was given testosterone," he said. "I was on growth hormones; I’m still on those things. My body didn’t go through the change by itself."

Max Casella split showing star as young actor to modern day
The now 55-year-old actor Max Casella shockingly revealed he didn’t hit puberty until the age of 27.

"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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Max Casella and Sylvester Stallone at Tulsa King red carpet premiere
"Boardwalk Empire" star Max Casella got candid about his growth journey during a "Tulsa King" premiere, as he co-stars alongside Sylvester Stallone.

The "Boardwalk Empire" star got candid about his growth journey during a "Tulsa King" premiere, as he co-stars alongside Sylvester Stallone.

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"Tulsa King" tells the story of Dwight Manfredi (Stallone) as he rebuilds his life after being exiled from his family by a crime boss following a 25-year prison stint. Manfredi is forced to create a new family of his own in Tulsa, Oklahoma, with a group of unlikely characters.

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Tulsa King cast at red carpet premiere
"Doogie Howser, M.D." alum Max Casella added that after meeting Stallone he had an "almost sh—in your pants moment" while working on "Tulsa King."

Despite Casella’s delayed puberty allowing him to play certain roles much younger than his actual age, he noted that it was a terrible experience.

"It was a horror show," he remarked. "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."

Meanwhile, the "Doogie Howser, M.D." alum added that after meeting Stallone he had an "almost sh—in your pants moment."

"I had his poster on my wall when I was 10 years old, and now I’m acting with him? It’s surreal," "The Sopranos" star confessed, according to the media outlet.

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"I’ve acted with a lot of big stars: Leonardo DiCaprio, Brad Pitt, Johnny Depp. Sometimes it’s up or down, your experience with them, but nobody like Sly, who was such a superhero to my 10-year-old self. This was like my boyhood dream."