A rare condition makes a Brazilian man's scalp look like his brain is on the outside of his head.

The 21-year-old man has a condition called cutis verticis gyrata, an overgrowth of skin on the scalp that causes "ridges and furrows resembling the brain's surface," doctors wrote in an article in this week's New England Journal of Medicine.

The condition is more common in men than women, and is mostly cosmetic, Global Post reported.

The condition "can be associated with some rare genetic conditions, but most commonly occurs by itself," Dr. Josh Zeichner, an assistant dermatology professor at Mount Sinai Medical Center, told ABC News.

The condition was first reported in 1843.