Drug maker Eli Lilly and Co said Chief Executive John Lechleiter will undergo a surgery on May 13 to treat a dilated aorta but is expected to recover and return to work by this summer.

Chief Financial Officer Derica Rice will serve as acting CEO while Lechleiter recuperates, as per the company bylaws.

Lead independent director Ellen Marram will serve as acting board chair in place of Lechleiter, who is also the company's president.

"The board of directors and I have the utmost confidence in Ellen, Derica, and our Lilly leadership team. The company will be in very good hands during my leave," Lechleiter, 59, said in a statement on Monday.

A dilated aorta generally refers to an abnormal swelling of the aorta, which is the largest artery of the body and crucial for blood circulation. An abnormal swelling can cause the aorta to rupture, leading to internal bleeding and can be fatal.

The CEO did not experience any symptoms related to the condition and discovered it while undergoing certain unrelated tests, Lilly said.

(Reporting by Zeba Siddiqui in Bangalore; Editing by Sriraj Kalluvila)