So what is fibrous dysplasia? The following is a general description based on my own experience and what I've gleaned from the Web. As you may have noticed in your own investigations, much of the available information on the Web is incomplete or contradictory. Hopefully, all of the following is accurate; if you disagree with me or know of something that I've excluded, please mail me.

Fibrous dysplasia is a genetic bone disorder, apparently caused by a gene or genes in the body that suddenly begins to malfunction. No one knows what causes this to happen, and there is no cure. Despite the genetic nature of the disease, it is not thought to run in families (some sources suggest that the tendency to develop the most severe form, McCune-Albright Syndrome, may be hereditary, but it is not reliably so). If you have fibrous dysplasia, your children are no more likely than the general populace to have the disease.

Fibrous dysplasia affects the body's ability to manufacture normal bones. In its severe (polyostotic) form, it can also affect other parts of the body such as the endocrine glands. It is not considered life-threatening, but may be painful and disfiguring.

As with some forms of cancer, the bone cells are "instructed" to start producing the wrong kind of tissue. In this case it is fibrous tissue like gristle, rather than hard, calcerous bone. On X-rays, bones with fibrous dysplasia have a characteristic look that is called a "ground-glass matrix"; this distinctive appearance is one of the key elements in diagnosis. The diseased tissue is like a honeycomb of fibrous tissue with bony spines embedded in it. One source on the Internet suggested that these needles of harder bone cause some of the pain associated with the disease by penetrating adjacent nerve tissue. That's certainly a good description of what it FEELS like. Pain is also caused, especially in weight-bearing bones, by small stress fractures caused by day-to-day activities. Over time, without treatment, these many small fractures can cause the bone to melt down. My doctor told me that without a reinforcing rod, my left leg would probably have come to be at least 3 inches shorter than the right.

The onset is usually in childhood. It may be as early as infancy or as late as adulthood, but most commonly affects schoolchildren and adolescents. I first began experiencing symptoms when I was 9 years old and was diagnosed at the age of 11, which seems to be a little later than the median age of onset. The disease seems to appear early and then to gradually decrease in severity--or at least the patient grows used to living with it. My doctor in Anchorage told me that it's thought to actually recede in some people, with abnormal bone gradually being replaced by regular bone, in a reverse of the original pattern. I have not found any sources on the Web that support this. However, the pattern of the disease appears to be predetermined even before it starts manifesting symptoms. In other words, you are born with it, though you may not know until later. It does NOT spread from one part of the body to another.

The bones most commonly affected are the ribs, femur, tibia, and skull, but any bones may be affected.

There are two forms of the disease. Monostotic fibrous dysplasia, the most common kind, affects only one bone of the body, while polyostotic fibrous dysplasia affects more than one bone. The two sometimes exhibit such different symptoms that they might almost be different diseases--and who knows, so little is really known about what causes this disease that perhaps they are. (Now the AMA will be after me for distributing misinformation.)

This is the "simple" form of the disease. Actually it can be quite painful and disfiguring, especially if it strikes the spine, skull, or face. (Fibrous dysplasia of the facial bones, commonly the jawbone, can cause severe disfigurement and dental abnormalities; when this happens, it is called cherubism because of the childlike appearance of the face.) Affected bones may also expand, sometimes grotesquely, due to the sponginess of the tissue.

Polyostotic fibrous dysplasia affects more than one bone in the body. The most severe form is McCune-Albright Syndrome, in which fibrous dysplasia (affecting most major bones) is only one of a number of symptoms, including: patchy skin pigmentation (like "cafe-au-lait spots"), premature puberty and early vaginal bleeding in girls, and endocrine abnormalities (not always) such as hyperthyroidism and adrenal abnormalities.

The bad news: rarely, polyostotic fibrous dysplasia has been known to mestatize into malignant cancer. (Statistically, however, the chance is not much greater than for any healthy individual to develop cancer.) Because of endocrine problems, McCune-Albright Syndrome is associated with increased risk of death from heart arrhythmias. However, the risks are slight overall.

Treatment for fibrous dysplasia is more a matter of controlling the symptoms than treating the cause. Surgery is often necessary to reinforce weight-bearing bones (such as the femur and spine) with metal prosthetics and prevent further deformity and injury. If the face and/or skull are affected, plastic surgery may be necessary to correct the resulting deformity. Otherwise, doctors may prescribe physical therapy, external braces, and painkillers to deal with physical impairment and discomfort. In extreme cases, bone grafts may be attempted, transplanting healthy bone to the affected areas. This is usually not effective in growing children, because the healthy bone quickly becomes affected as well. I don't know if bone grafts have been tried in adults.

A new possibility is hormone treatments. Fibrous dysplasia has been associated with elevated levels of a blood protein normally found in connection with some kinds of tumors. Some experimental diet supplements, given to children with McCune-Albright Syndrome, have appeared to lessen the severity of the disease. I don't have much information on this, unfortunately. (Warning: speculation ahead!) It seems to me that since fibrous dysplasia is such a dynamic disease, with the affected bone continually being replaced by the body's natural processes just as healthy bone is, hormone therapy offers the potential of being able to reverse its progress and even restore healthy bone, even in adults. It's much too soon to be optimistic.

More information on monostotic fibrous dysplasia, and on living with fibrous dysplasia, is found in my biography.

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