Diagnostic dilemma: Weird spikes poking through a teen's eyelid turned out to be a wayward tooth

The patient: A 16-year-old boy in India

The symptoms: The teen developed swelling on his left upper eyelid that persisted for a few months but was painless. However, he later noticed two sharp, white projections poking out from the skin above his eye.

About a month after these projections appeared, he went to a hospital.

What happened next: Doctors examined the teen's eyelid, noting that the spikes had a "fairly smooth surface and were hard on palpation," said Dr. Meghana Tanwar, a medical consultant at the Aravind Eye Hospital in India who co-authored a report of the case. The texture and color of the projections suggested they might be teeth, she told Live Science in an email.

Initially, the doctors thought the points also might have been related to a teratoma, a rare type of tumor that can include different types of tissue, including bone and tooth tissue. They also wondered if the projections might be a foreign body in the eyelid. They conducted a CT scan to take a closer look.

The diagnosis: The scan revealed that the projections were indeed part of a tooth.

"The structure of a lone tooth in the superior orbit was quite obvious," Tanwar said. "Superior orbit" refers to the upper eye socket, and the tooth had poked out in the small space between the boy's eyelid and eyebrow.

Teeth that develop and erupt in abnormal locations are known as ectopic teeth. This umbrella term includes teeth that are in the mouth but erupt outside their typical positions; for instance, in about 2% to 6% of people, their first permanent molars grow "out of place" in the expected line-up of teeth.

In this case, though, the patient had an ectopic tooth that appeared completely outside the dental arch, which is far rarer.

The treatment: The doctors surgically removed the ectopic tooth from the patient's eyelid and found that it was a mature canine tooth. It didn't have any features that suggested it was part of a teratoma.

"Since the imaging done did not show the presence of any other ectopic teeth, the likelihood of him having another one are unlikely," Tanwar noted.

What makes the case unique: This is not the first ectopic tooth in the medical literature, but it was in a very notable location.

"To the best of our knowledge this is the first and only ectopic tooth reported in the superior orbit," Tanwar said. Previously, they've been reported in the nasal cavity and the bottom of the orbit, under the eye, she noted. According to MedPage Today, they've also been found in the nostrils, chin and maxillary sinus, which is located inside the cheekbone.

"This was a first not just for us but the world over," Tanwar said of the case. "We were very surprised by it."

Prior to the case, Tanwar had personally seen a tooth in the bottom of the eye socket of a different patient, but it was part of a rare type of mass called an odontogenic choristoma.

In this teen's case, the underlying cause of the ectopic tooth was unknown. Hypotheses suggest that, in general, ectopic teeth may grow out of place due to developmental disorders, physical trauma, infection or genetic factors.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.