Rep. Alan NunneleePatrick (Alan) Alan NunneleeTrent Kelly sworn in as House member Democrat advances to runoff in Mississippi special election House holds moment of silence for Rep. Nunnelee MORE (R-Miss.) will undergo surgery next Monday to remove a small mass found on the right side of his brain.

According to the two-term congressman's office, doctors say the small mass inside Nunnelee's skull is isolated.

He arrived at MD Anderson Cancer Center in Houston on Wednesday. 

“I have been blessed throughout this process to not only have a great team of doctors, but also your prayers and support," Nunnelee said in a statement. "I am grateful for your continued prayers, thoughts, and well-wishes for a speedy recovery.” 

The Mississippi Republican said it is his responsibility to keep his constituents informed of his medical situation but did not offer any indication how long his recovery would take. He said his office would continue to be available to constituents. 

"Please continue to let us know if our office can be of assistance," he said. 

Nunnelee, 55, was first elected in 2010 after defeating former Rep. Travis Childers (D-Miss.), who earlier this week won the Democratic nomination for the Senate in the state. 

Shortly after the 2012 election, Nunnelee underwent successful heart valve replacement surgery. He was uncontested in his House primary on Tuesday.