When doctors noticed the head of a four-month-old baby growing at a quicker pace than normal, they scanned his brain and found a tumor with teeth — literally.

While it's extremely rare, the infant from Maryland had a specific type of brain tumor containing fully formed teeth.

In a report of the case published in the New England Journal of Medicine, doctors reveal that the brain scan showed the presence of a tumor with several teeth similar to those found in the lower jaw.

A First Time

Upon analysis of the tumor tissue, the child was diagnosed with craniopharyngioma, which is a type of brain tumor that can swell as big as a golf ball but doesn't spread. Amazingly, there have been no known cases of this type of tumor with teeth.

"It's not every day you see teeth in any type of tumor in the brain. In a craniopharyngioma, it's unheard of," Dr. Narlin Beaty, a neurosurgeon at the University of Maryland Medical Center and one of the surgeons who performed the baby's brain surgery, tells Live Science.

He adds that researchers have long believed that this type of tumor is made up of the same cells that make teeth, although it's common for craniopharyngiomas to be found with calcium deposits.

This particular case in Maryland provides further evidence that craniopharyngiomas actually develop from the same cells as teeth.

Usually, tumors with teeth are teratomas, which is a type of tumor with all three tissue types found in a human embryo in its early stages.

According to Mayo Clinic, craniopharyngioma can be found in people of all ages, but it often occurs in children and older adults.

Baby Boy In Recovery

While the infant is developing well, the tumor did destroy some connections in his brain that's in charge of releasing certain hormones, according to Beaty. This means that he would have to take hormone treatments for the rest of his life.

It's typical for craniopharyngiomas to cause problems in hormones since it is a tumor of the pituitary gland.

Still, the infant is recovering well, especially coming off a major brain surgery. Doctors are routinely following up on his status with MRI, while his teeth were sent to a pathologist for further analysis.

"He's doing extremely well, all things considered," Beaty says. "This was a big tumor right in the center of his brain. Before the modern surgical era this child would not have survived."