Dance Moms star Abby Lee Miller said goodbye to her hair Sunday as she braces for the impacts of chemotherapy.

Abby, who began her third round of chemotherapy earlier this month, shared her message on Instagram: "HAIR TODAY, GONE TOMORROW..." she wrote, along with the hashtag #chemo.

The post comes days after the 51-year-old reality TV star was spotted moving around in a wheelchair, reports People.

Just weeks ago, on June 5, Abby underwent emergency surgery as part of her ongoing fight with a rare form of cancer known as Burkitt lymphoma (a type of non-Hodgkin's lymphoma), according to ET Online. Her diagnosis came after undergoing another emergency surgery in April for what doctors thought was spinal infection.

What is Burkitt lymphoma?

In case you’re not familiar with it, Burkitt lymphoma is an aggressive form of non-Hodgkin's lymphoma, a type of cancer that affects white blood cells, according to the American Cancer Society (ACS).

With Burkitt lymphoma, the cancer usually starts in a person’s abdomen, where it forms a large tumor. It can spread rapidly to the brain and spinal fluid. It is very rare, according to the ACS—making up just 1 to 2 percent of all lymphomas.

“Burkitt lymphoma is very aggressive,” says Jack Jacoub, M.D., a medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast Medical Center in Fountain Valley, Calif. “It can be lethal in a matter of weeks with no therapy.” Luckily, the ACS says that more than half of patients can be cured by “intensive chemotherapy.”

There's no word on how much longer Abby's treatment is expected to take, but for her specific type of cancer, treatment generally involves undergoing chemotherapy cycles for four to five months, Jacoub says. That can include chemotherapy injections into the spine as well as intravenous chemo.

Abby Lee Miller's cancer side effects

Abby has been in the hospital since mid-April, per Page Six, but has been diligent about updating her fans on her journey, even sharing a closeup of her face bathed in sunlight on Instagram.

“Going outside to feel the sun on my face was wonderful!!!” she wrote on Instagram in early June. “Kids, never take anything in this world for granted! It can all change so suddenly! The Brilliant Dr. B cleared me for sunning this afternoon! Woo Hoo! Thank you sir!”

Jacoub says people who undergo chemo can burn a lot easier and quicker than others. He adds that doctors usually advise patients not receive direct, prolonged sun exposure for several weeks after their last chemotherapy session. However, it’s probably okay to briefly grab a few rays here and there.

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