Doctors in Russia removed a tooth that was growing inside a 13-year-old boy’s testicles.

The tooth in question was a molar that had begun growing inside the unidentified teen’s testicles instead of his mouth. After surgeon Dmitry Tarusin, a senior children's urologist and andrologist at Morozov Children's Hospital, observed the boy missing a molar in his upper jaw, he noticed what initially looked like renal gravel (gravel in kidneys) in the patient’s testicles.

"Doctors decided to operate on the patient as soon as possible,” the hospital said, Daily Mail reported. “The surgery proved that the real seventh tooth – a molar – was growing inside the testicle, the one that was missing in the jaw. Dental science knows examples when teeth grew inside the lung. But a tooth growing inside a testicle is a truly unique case.”

The surgery was a success and medical experts said the boy was expected to enjoy good reproductive health after he becomes an adult. They added that the cause of the anomaly was a teratoid tumor originating before birth due to a stem cell failure.

Doctors
In this photo, surgeons at The Queen Elizabeth Hospital Birmingham conduct an operation, Birmingham, England, June 14, 2006. Christopher Furlong/Getty Images

The hospital said the “rarest of surgeries” was a result of “genetic process during the prenatal period.” “The tooth was the second molar or the seventh in the upper jaw,” the statement added. “It usually replaced by the permanent tooth at the age of ten to 12.”

It was not exactly known when the surgery was carried out. No further details about the procedure were available.