Doctors at Bethesda Naval Medical Center removed a small cancerous lesion from the tip of President Reagan's nose yesterday afternoon in a procedure that the White House and cancer specialists described as routine.

"He's in excellent spirits," said White House spokesman Marlin Fitzwater after the president's two-hour surgery. He said that doctors had decided against grafting a small patch of skin from behind his ear.

The president left the hospital at 7:45 p.m. and returned to the White House by helicopter with a large flesh-colored bandage on his nose. "I feel fine," he said to reporters. The Reagans canceled plans to spend the weekend at Camp David. Doctors had originally considered keeping the president overnight in the hospital.

It took approximately 20 stitches to close the wound caused by the surgery, which was 12 millimeters in diameter and 5 millimeters deep, White House officials said. The president's doctors said the stitches will be removed in five to seven days. A statement by Col. John E. Hutton Jr., the White House physician, said Reagan "will receive pain medication such as Tylenol as required."

The operation was scheduled Wednesday after tests on a small piece of skin from the area revealed a basal cell epithelioma, among the most common and least dangerous forms of skin cancer.

It is the third time in two years that the president has had skin cancers removed from his nose. Skin cancer specialists said yesterday that it is not unusual for basal cell growths to recur and that they are particularly common on the faces of older adults with fair skin who spend a great deal of time outdoors.

The operation was performed under local anesthesia, and medical experts said it was not complicated. The president received approximately three to four cc's of Xylocaine with epinephrine as a local anesthetic.

"This is a routine procedure," said Dr. Philip G. Prioleau, director of dermatologic surgery at New York Hospital-Cornell University Medical Center. "It's safe and simple."

He said there was very little risk involved in the surgery and that basal cell cancers are not as dangerous as other cancers because they are local and don't spread to other regions of the body.

Three doctors performed the operation yesterday. Capt. Theodore Parlette, chief of dermatology at Bethesda naval hospital, Hutton and Rear Adm. William M. Narva, the physician to Congress, who is also a dermatologist.

The president's doctors used a surgical procedure called Mohs' technique. The visible growth was removed with a scalpel. Then the surgeon took a thin sample of the skin around the wound and gave it to pathologists at the hospital. They froze the skin, cut it into thin sections and microscopically examined it to determine whether any cancer cells remained.

After finding that cancer cells remained, the doctors removed another extremely thin slice of skin, which was similarly examined and found to be free of abnormal basal cells, according to the statement by Hutton. After that, the doctors decided not to graft a small patch of skin from the president's ear, instead using sutures.

The processs normally takes about 30 minutes and it is repeated until cancer cells are no longer present. The doctors had considered sending the tissue to a lab for analysis, which would have taken much longer.

"Going back for two slices is not unusual at all," said Dr. Perry Robins, president of the Skin Cancer Foundation. "That's the reason this techinique is so useful. It makes certain we get all the cancer."

He said that at least 400,000 people undergo similar operations for basal cell cancers each year. He said that up to four times as many cases go untreated.

The vast majority of basal cell cancers are found on the face, other parts of the head and neck. Most are caused by damage to the skin by decades of exposure to sunlight.

Reagan had a basal cell skin cancer removed from his nose on July 30, 1985, about two weeks after he had major surgery for colon cancer. A second basal cell skin cancer was removed from Reagan's nose on Oct. 10, 1985.

Since then, the president has received frequent examinations to check for further skin cancers. Doctors said yesterday that Reagan would be checked about once a month for the next year or so. Staff writer David Hoffman contributed to this report.