SHE’s a pint-size mom facing a Goliath-size battle. But cancer-stricken “Little Couple” reality star Jennifer Arnold is hoping for a miracle – and medical experts say she has a fighting chance.

Millions of TLC viewers have been follow­ing the lives of 3-foot-2 Jen and her 4-foot husband Bill Klein, who both have dwarfism, since they were newlyweds in 2009. During that time, the two relocated from New York to Houston, built a custom home and adopted two children from abroad.

But now they face their biggest drama. In October, Jen was diagnosed with Stage 3 cho­riocarcinoma, a rare cancer that formed during a nonviable pregnancy, and she’s undergone surgery and chemotherapy. Jen’s medical team admits that figuring out the proper dosages for the 39-year-old is tough, since cancer in folks of her stature is extremely rare.

As a result, treatments have left Jen – a neonatologist on staff at Texas Children’s Hospital in Houston – exhausted, bald and battling potentially deadly infections.

Through it all, Jen’s been open about her struggles. On Dec. 30, a few days after getting chemo, she posted on the Internet: “It’s been a rough couple of days, time for some bath therapy!”

Now two leading experts – who have not treated Jen – tell The ENQUIRER they’re optimistic about her survival.

“It seems as if she has a fairly advanced dis­ease, Stage 3,” said Dr. Jerome Spunberg, a radiation oncologist from West Palm Beach, Fla. “But with aggressive chemotherapy, the response rates and survival are surprisingly high, say 50 to 75 percent at five years.”

Dr. Herman Kattlove, former spokesperson for the American Cancer Society, added: “Her chances of survival are probably pretty good. This is the first cancer ever found curable. But, as always with individual cases, the devil is in the details.”

Meanwhile, Jen’s 39-year-old businessman hubby Bill is caring for their adopted tykes – son Will, 3, from China, and daughter Zoey, 2, from India.

He’s also playing nurse to his ailing wife. Needle-phobic Bill is giving Jen injections, writ­ing: “Jen’s scared I’ll pass out. Funny, so am I.”

But the gutsy couple refused to let Jen’s illness ruin their Christmas. Jen’s father Dave Arnold dressed up as Santa Claus to surprise the tots while she baked cookies and Bill prepared a seven-course dinner for the family.

Heartfelt wishes for Jen have poured in from around the world, with TLC’s other tiny star Amy Roloff of “Little People, Big World,” writing: “You can & will beat this. Thinking of you.”

Fans have also rallied to Jen’s side, according to her sister-in-law’s father, Mike Dewey.

“The response from fans has been overwhelmingly positive, and after the initial concern, everything is going fine,” Dewey told The ENQUIRER.

“Bill was a little concerned, as one would be when get­ting such a diagnosis. But now everybody is positive about it. We’ve sent out prayer chains for Jen and we’re elated that things are going in the right direction.”