Tipper Gore, the wife of Vice President Gore, returned home from Johns Hopkins Hospital in Baltimore yesterday after surgeons removed a lump from her thyroid gland.

The lump, or nodule, was removed during a two-hour surgical procedure Tuesday after preliminary tests to see if it was cancerous proved inconclusive, hospital officials said.

Pathologists will conduct more definitive tests on the nodule and results are expected early next week, according to Robert Udelsman, the Johns Hopkins surgeon who led the procedure.

Nodular growths on the gland are common, occurring in as many as one-third of all adults, and more than 90 percent are noncancerous, according to the American Cancer Society.

"The surgery went well and she's been resting comfortably," hospital spokeswoman Marjorie Centofanti said yesterday. The vice president spent Tuesday night at the hospital with Mrs. Gore and the two left, arm in arm, early yesterday afternoon. All four of their children visited during her stay.

The thyroid gland is a butterfly-shaped organ located near the voice box in the neck. It secretes hormones that regulate metabolism and body temperature.

Usually a nodule's status as benign or cancerous can be discerned by examining a tiny sample retrieved with a fine biopsy needle. Those deemed benign often are left alone, unless they are large enough to interfere with swallowing or are cosmetically troubling.

But in 10 to 15 percent of cases, including Mrs. Gore's, biopsy results are ambiguous and the nodule must be surgically removed for examination, according to Simeon Margolis, a Johns Hopkins endocrinologist who answered questions about the condition on a Hopkins Web site.

If tests on the nodule indicate Mrs. Gore does have thyroid cancer--a diagnosis received by about 18,000 Americans (13,500 of them women) this year--the organ would almost certainly be removed and a follow-up treatment of radioactive iodine, which helps prevent recurrence, might be administered later, doctors said.

More than 95 percent of people remain free of thyroid cancer for at least five years after such treatment, as long as the cancer has not spread to distant sites before surgery.

Mrs. Gore, 51, discovered the nodule several months ago during a neck examination for a sports-related injury, said Gore office spokeswoman Camille Johnston. Mrs. Gore, an avid jogger, has had no symptoms of thyroid disease, Johnston said.

Udelsman said the Gore family has asked him not to discuss details of Mrs. Gore's case. But in general, he said, surgery to remove thyroid nodules does not affect the gland's ability to do its job. In cases when the thyroid must be removed, its functions are effectively replaced with synthetic thyroid hormone pills.

The surgery that Mrs. Gore had, called a right thyroid lobectomy, is conducted under general anesthesia and can be a little tricky, Centofanti said, because key nerves that control the vocal cords and breathing pass nearby and must be spared.

Johnston said Mrs. Gore is able to speak and is "feeling great" but will not have a public schedule next week.

Staff writer Mike Allen contributed to this report.

CAPTION: Vice President Gore thanks Johns Hopkins surgeon Robert Udelsman, who operated on his wife's thyroid.