Dick Howser, manager of the World Series champion Kansas City Royals, underwent surgery today in which a malignant tumor in the left frontal lobe of his brain was partially removed, doctors said.

Dr. Paul Meyer, team physician for the Royals who observed the surgery, said the tumor was malignant. Meyer said it was only partially removed for fear of damaging the brain, particularly the portion that controls speech.

Meyer said doctors did not know what form further treatment will take, but that radiation therapy is possible. The treatment is dependent on a full pathology report, which physicians said would not be available for at least two days.

Dr. Charles Clough, the neurosurgeon who preformed the operation, said the tumor "appeared to be a type of tumor called a glioma." A glioma tumor also is called a primary tumor and Dr. Robert Morantz, a Kansas City neurologist, told the Kansas City Star last week that primary tumors are the most deadly and the most difficult to remove.

Clough said in a statement read at a news conference that Howser's wife, Nancy, was with him in the recovery room and he described the 50-year-old manager as awake and alert. He said Howser was able to speak and move all four extremities.

The Royals, in Baltimore to play the Orioles, were told about the operation moments before batting practice in a meeting with General Manager John Schuerholz. Earlier, they held a prayer meeting with a Baltimore priest.

"This isn't the news we'd hoped for," third baseman George Brett said. "He knows there are 24 players and a coaching staff here rooting for him, and I know Dick, he's going to approach this with an attitude that he can beat it."

Mike Ferraro, the Royals' acting manager and a close friend of Howser's, wept as he attempted to speak with reporters. "You can't prepare yourself for something like this," Ferraro said. "He's a battler, I'll tell you that. He'll fight like hell."

Ferraro said when the players heard the news, "a few heads hung. There's a sense of disbelief."

The operation started at 11:30 a.m. Dave Witty, a Royals spokesman, said Howser was out of surgery four hours later.

Howser, who guided the Royals to victory over the St. Louis Cardinals in the 1985 World Series, was admitted to St. Luke's Thursday night. Just 48 hours earlier, he had managed the American League to a 3-2 victory in the all-star game in Houston.

He had complained for two weeks of a stiff, sore neck and associates said he had begun showing signs of mental confusion. During the all-star game, Howser "was totally out of it," according to Ferraro.

The tumor was discovered by a CAT scan on Friday morning.

Howser was a shortstop with Cleveland, Kansas City and the New York Yankees during an eight-year major league playing career beginning in 1961.

Orioles General Manager Hank Peters was farm director of the Kansas City A's and gave Howser a $21,000 bonus to sign his first professional contract in 1958.

"I've watched him grow up," Peters said. "I don't know how to express this. He was a player who made the most of his ability. I think that's the best way to explain what kind of person Dick Howser is."

President Reagan sent a get-well message to Howser as he was being prepared for surgery.

"We just want to add our voices to those of your many friends and fans in sending good wishes for a complete and speedy recovery," the telegram read. "We'll be keeping you in our thoughts and prayers."

Staff writer Richard Justice, in Baltimore, contributed to this report.