Rob Delaney started writing a book about his son's battle with a brain tumor but scrapped it when he learned his son only had months to live.

The "Catastrophe" actor's 2 1/2-year-old son, Henry, died of brain cancer in January, but Delaney shared pages in an essay on Medium this week because he wanted fellow parents with sick children to know they're not alone.

The actor, 41, says he wrote the passage when his son was sick in April and May of 2017.

"The reason I’m putting this out there now is that the intended audience for this book was to be my fellow parents of very sick children. They were always so tired and sad, like ghosts, walking the halls of the hospitals, and I wanted them to know someone understood and cared. I’d still like them to know that, so here these few pages are, for them. Or for you."

Getting a diagnosis

Delaney's son, Henry, began vomiting off and on. One doctor thought it might be a UTI. A gastroenterologist prescribed a drug to prevent vomiting. Henry began to lose weight from the vomiting. A friend recommended a pediatrician who quizzed them further on the vomiting. Was it "effortless?"

“Hmm, huh, um, it is effortless, yeah. He’s not troubled at all,” Delaney recalled.

The doctor suggested an MRI.

"Just to make sure there’s nothing in there that shouldn’t be. Pressing on his emetic center, making him vomit." “What, like a tumor?” He paused. “I’m glad you said it.”

Henry's diagnosis: An ependymoma tumor on the brain, which is often deadly.

Crying, love and smiles

Delaney recalled in heartbreaking detail that the removal of the tumor wreaked havoc on his son's body and took an emotional toll on him. Because of it's location, the tumor's removal damaged Henry's cranial nerves, causing Bell’s palsy that left him with facial paralysis and made him deaf in his left ear. A tracheotomy tube prevented Henry from speaking.

"My wife recently walked in on me crying and listening to recordings of him babbling, from before his diagnosis and surgery ...oh my God I want to hear him again."

But Delaney said though he longed to have his three sons under one roof again, he was "always, always happy to enter the hospital every morning and see him. It's exciting every day to walk into his room and see him and see him see me."

Delaney added that a half smile from Henry filled his heart.

"And when he smiles, forget about it. A regular baby’s smile is wonderful enough. When a sick baby with partial facial paralysis smiles, it’s golden. Especially if it’s my baby."

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