Toothy tumor discovered in brain

Inherent in its Latin root tumere, meaning “to swell,” a tumor describes an abnormal growth of cells. It is a bodily excess, something indispensible, often necessarily, for proper bodily functions. This modern conception of tumorous growths leaves no room for functional structures in the abnormal mass. Imagine the surprise, then, when a team of doctors at Johns Hopkins Hospital found fully grown teeth in the brain tumor of a four-month-old child.

In 2012, the mother of the child took him to the doctor for a stuffy nose. The pediatrician noticed that the child’s head was growing faster than expected from past medical measurements. After an ultrasound and a CT scan, the child was diagnosed with a brain tumor and rushed to Hopkins Hospital.

Edward Ahn, a pediatric neurosurgeon at Johns Hopkins Hospital, was the lead surgeon in the child’s case. He recognized the tumor as a crainopharyngioma, a rare mass that generates pressure in the brain by pressing against the pituitary gland and the optic nerve. During surgery, Ahn found pieces of white matter in the tumor. He originally thought nothing of them, as crainopharyngiomas often present with calcium desposits. Upon closer inspection, however, Ahn thought the bits of white looked like teeth. A pathologist later confirmed this judgment.

Teeth are not unprecedented facets of tumorous growths. Teratomas, colloquially called “hairy-toothy-tumors,” often contain bits of teeth or strands of hair. However, unlike craniopharyngiomas, teratomas are derived from stem cells. Because stem cells are pluripotent, meaning they can adopt many different cell fates, the dividing cells of a teratoma can differentiate into many cell types. Sometimes, these abnormally dividing cells cooperate and form identifiable structures.

Craniopharyngiomas are not derived from stem cells. Thus, it is unclear how the cells comprising a craniopharyngioma can form a fully-grown tooth. Ahn thinks it has something to do with the origin: The cells of a craniopharyngioma may have a common lineage with pre-teeth cells. This may give them certain developmental markings for teeth. In fact, these tumors often include other calcifications, keratin and fragments of teeth. However, this particular case is interesting because the tumor included a very rare fully formed tooth.

The Hopkins team that conducted the 2012 surgery published an article on the tooth-infested tumor in a February edition of the New England Journal of Medicine. This research could prove extremely useful for developmental biologists, as it may illuminate factors or pathways that restrict cell fates.

The four-month-old patient is now two years old and walking. During the original surgery, the Hopkins team could not remove the whole tumor because of its proximity to major blood vessels. This has left the child with some vision problems. Currently, the patient is following a hormone-replacement regimen and goes to Hopkins for regular checkups.