From one angle, it's almost unnoticed: the droop of his nose, the concave cheeks, the pinched mouth with 13 teeth — three top, 10 bottom, too few to chew steak.

The face of a child.

But Filmon Haile is 19.

"Look how small it is," said Dr. Edward Zebovitz, lifting a plaster cast of Haile's jaws. The bottom one is about an inch long.

It's a Friday morning at Anne Arundel Medical Center in Annapolis, Md., the day Zebovitz, the former chief of oral and maxillofacial [face] surgery at the hospital, will embark on the most demanding operation of his 20-year career.

Down the hall, Haile waits with his mother. They traveled nearly 7,000 miles from the Horn of Africa, the city of Asmara, capital of Eritrea — where Haile would hide his face beneath a black scarf.

Filmon Haile, from Asmara, the capital city of Eritrea, in east Africa, at the home of his sponsor, Mike Naizghi, on July 30, 2015 in Bowie, Md.

"When I met him, I was like, what did he have?" Zebovitz said. "There was no syndrome that he fell into."

Haile arrived with medical records, though. He was 2 years old when a tumor grew on his cheek.

Radiation, on Haile's face, stunted growth. His body developed, but his face lagged. Surgery "is going to change my life completely," Haile said.

Zebovitz spent weeks planning the cuts along cheekbones, eye sockets and jaws. Titanium devices will be screwed on cut bone beneath the skin. These devices, called distractors, will extend screws behind Haile's ears.

The screws will be turned and, millimeter by millimeter, bone will separate; the process is similar to the way dental braces work. The titanium plates open like elevator doors, and bone regrows in the gap.

"It's all engineering," Zebovitz said.

Haile himself will turn the screws each day.

The technique was developed in the 1950s by Russian professor Gavriil Abramovich Ilizarov, mostly to lengthen the bones of patients with uneven legs. In the 1990s, said Dr. Douglas Fain, it was applied to bones of the face.

Still, Haile's surgery is ambitious. "Because of radiation therapy at such a young age and just how big the magnitude of the movements are," Zebovitz said.