"I have recently been diagnosed with a rare type of cancer and am currently undergoing treatment, including surgery and chemotherapy," Arnold toldPeople.
Arnold, a 39-year-old Houston-based neonatologist, and her husband Bill Klein, a 38-year-old entrepreneur who runs Rocky and Maggie's Pet Shop in Houston, have two children together. They have a three-year-old son named Will whom they adopted from China and a two-year-old daughter Zoey whom they just recently adopted from India.
"I am very fortunate as the prognosis is good," added Arnold.
"While there is never a good time to get news like this, getting it just as we are building our new family is tough in many ways... But being surrounded by the love of my husband and our two beautiful children is actually in many ways giving me the strength to fight it even stronger."
It remains unclear exactly what type of cancer Arnold is currently battling.
Arnold has reportedly struggled with fertility and surrogacy issues for quite some time, and she's had about 30 procedures and operations related to her type of dwarfism. The love she shares with Klein, however, apparently gets them through difficult times.
"Jen has achieved so many great things," Klein told People earlier this year. "We are so in love with each other and supportive of each other that we are going to be ok. Few people are so lucky to have what we do, from the moment you meet that one person and everything that you do together, everything that you add to that relationship is exciting as well. We are up for challenges."