Doctors removed a 2-pound tumor from the back of a newborn's neck and the baby girl appeared to be doing fine, her parents said.

"The first thing we want to do is hold her head," the baby's father, Joshua Whittington, a 31-year-old pharmacist from Denver, told the Rocky Mountain News.

Addison's story unfolded quickly when her mother, Kari Whittington, visited her doctor's office Monday and an ultrasound detected the fast-growing, grapefruit-sized tumor. No abnormalities were detected in the previous ultrasound a month earlier.

Pediatric surgeon Steven Rothenberg said the growth, called a cervical teratoma is rare and occurs in about 1 in 50,000 births. The blood-swollen tissue and veins made up 40 percent of Addison's weight.

Addison, five weeks premature, was delivered by Caesarean section Thursday and stabilized before a nine-person surgical team started working on her.

"The mass itself started to spontaneously bleed ..." Rothenberg said. "If we'd been short one pair of hands, she wouldn't have made it."

Addison faces up to a two week hospital stay. As for the scar on her neck and along her jaw line it should disappear over time, Rothenberg said.

"It was definitely overwhelming," said Kari, 28. "Everything happened so quickly."