Q. My gynecologist told me that I had a fibroid tumor on my uterus. I've certainly heard of this condition before, but I realize I'm not quite sure what it is. Does having a fibroid mean I'll have to have a hysterectomy? My doctor says she wants to check me again before deciding.

A. Fibroids are benign (noncancerous) tumors of the muscle fibers of the uterus. The medical term is leiomyoma, meaning smooth-muscle tumor. Doctors aren't sure what causes fibroids to grow, but they're extremely common and can range in size from a small nub on the uterus to a large mass resembling a pregnancy.

Most of the time, fibroids don't cause any symptoms and are first discovered during a routine pelvic exam. In such cases, no treatment is necessary, especially if they're not overly large. This is particularly true if you're close to the menopause, because fibroids tend to shrink after you stop having periods. However, your doctor may want to re-examine you every six months or so initially to make sure the fibroid isn't rapidly getting bigger.

Occasionally, fibroids can cause troublesome symptoms, for which you may need treatment. Reasons for having surgery include:

Heavy or irregular menstrual bleeding, especially if this causes anemia.

Pressure symptoms on your bladder or bowels, making you urinate more often or giving you constipation.

Pain that may be a dull ache, a heavy sensation or sudden and severe cramping if a fibroid is on a stalk -- like the end of a dumbbell -- and twists, cutting off its blood supply.

Rapid growth of a fibroid.

Large size, usually at least as big as a three-month pregnancy.

Infertility or miscarriages believed caused by a fibroid.

Being unable to tell whether a growth in the pelvis is a fibroid or another type of tumor.

Surgery can be one of two types: either removing the fibroid alone (myomectomy) and leaving the rest of the uterus, or removing the entire uterus (hysterectomy). Because it's usually possible to get pregnant after a myomectomy, women desiring to have children would want to have just the fibroid removed if possible, even though others may grow later. For women after menopause, or those not wishing to have any children, a hysterectomy is usually the best treatment.

Q. My soon-to-be husband and I are very concerned about having children. His father had neurofibromatosis (the Elephant Man's disease), and we are worried that we might have an affected child.

My fiance has thus far shown no signs of the disorder, nor have his siblings. Please tell me the chances of our having children born with this disease, and if there are tests to indicate its presence before birth.

A. Neurofibromatosis -- meaning "nerve tumor" -- is a hereditary disease affecting the growth of nerves. The are two main types; the most common one, also known as NF-1 or von Recklinghausen's disease, shows up in about 1 in every 4,000 persons. The other form (NF-2) is rare, affecting 1 in 50,000 persons.

Although widely associated with the Elephant Man -- a horribly disfigured young man with NF who was exhibited as a freak in the 1880s and made famous in a play and film -- NF rarely causes such deformity. NF has two key signs: large skin freckles, called cafe-au-lait spots because of their coffee-with-cream color, and nerve tumors or neurofibromas.

People with NF typically have six or more cafe-au-lait spots on their skin (tan irregularly shaped freckles, larger than half an inch in adults or one fifth of an inch in children) or freckling in the armpits or groin, two places that are usually free of freckles in people without this disease. Faint cafe-au-lait spots show up better under ultraviolet light. Another sign of NF is Lish nodules on the iris of the eye, which an ophthalmologist can see with a special slit-lamp exam.

Neurofibromas can grow on any nerve at any time during the life of a person with NF. Most nerve tumors cause no symptoms, but on certain nerves they may cause problems such as deafness (seen in NF-2) or disability. Associated disturbances in bone growth can lead to deformity, such as curvature of the spine (scoliosis) or bowlegs.

About half of NF cases are inherited from an affected parent; the other half occur with no previous family members affected. However, once someone has NF, each child born to that person has a 50 percent chance of having the disease. Prenatal, as well as pre-symptomatic tests, though not yet available, are expected to be possible within two years.

I assume your fiance has already been examined for signs of NF. If none has shown up, odds are in your favor that he doesn't have this disorder. If so, you have no increased risk of having a child with NF. If he does have it, your chances of having an affected child are one in two.

If your fiance is affected, it's important to know that the severity of NF varies from person to person. Although the course of NF is unpredictable, serious complications are the exception rather than the rule. As yet, there is no cure for NF; treatment consists of correcting complications when possible, often through surgery.

For more information about NF, contact the Metropolitan Washington Chapter of the Neurofibromatosis Foundation, 3401 Woodridge Ct., Mitchellville, Md. 20716; phone 577-8984.

Jay Siwek, a family physician from Georgetown University, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington.

Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Questions cannot be answered individually.