Courtesy C-SPAN

His communications director, Adam Jentleson, tells ITK that Reid underwent the skin treatment on Wednesday and routinely gets the unspecified procedure done about every six months to a year.

Jentleson reiterated that the four dark-colored spots aren't indicative of a serious health problem. “It’s nothing,” Jentleson said.

Reid jested about the coloring on Thursday. 

"The marks on my face have nothing to do with fiscal cliff or disagreements between Speaker [John] BoehnerJohn BoehnerLast Congress far from ‘do-nothing’ Top aide: Obama worried about impeachment for Syria actions An anti-government ideologue like Mulvaney shouldn't run OMB MORE and I. It has to do with being very pale and living in the desert my whole life," the senator said. 

Boehner (R-Ohio) reportedly told Reid to "go f--k yourself" during a heated confrontation before a "fiscal cliff" meeting last week at the White House.