Hereditary desmoid disease (HDD) is a condition that causes people to develop a benign (noncancerous) growth known as a desmoid tumor. Desmoid tumors may also be called fibromatosis.
Description
In HDD, multiple family members from several generations develop desmoid tumors. These tumors are very rare. They account for fewer than 0.1% of all tumors diagnosed. The term "desmoid" comes from the Greek word for "band." That describes these tumors well, as they have a tendon- or ligament-like appearance. They usually occur in the abdomen, but they may also develop in the neck, chest, arms, and legs.
Desmoid tumors may appear due to mutations, or changes, in a gene called adenomatous polyposis coli (APC). Most desmoid tumors, though—more than 97%—occur sporadically, meaning that they are not caused by genetic mutations. People who develop sporadic desmoid tumors have no other health problems associated with mutations in the APC gene and have no close family members with the tumors. In the past desmoid tumors were classified as fibrosarcomas (growths associated with cancer), but this is no longer the case.
Mutations in the APC gene usually result in familial adenomatous polyposis (FAP). This condition causes hundreds to thousands of polyps (tiny growths) to develop in the colon. It is associated with a high risk for developing colon cancer. People who have FAP need to have their health monitored on a regular basis. Colon cancer can be prevented by careful medical screening and removal of the colon.
Some families with FAP develop extra-colonic symptoms (involving organs other than the colon), including desmoid tumors. The combination of colon polyposis and desmoid tumor was once termed "Gardner's syndrome," but it is now known that the two conditions are the same. Other extra-colonic features seen in families with FAP are cysts in the jawbone, skin cysts (epidermal cysts), bony bumps on the skull, a specific kind of spot on the retina, and thyroid cancer. About 10% of people with FAP will develop desmoid tumors. However, the risk differs from family to family.
In HDD, multiple family members over two or more generations develop desmoid tumors, but not colon polyposis. Family members in subsequent generations will have an increased risk of developing desmoid tumors.
Genetic profile
Every person diagnosed with HDD has a 50% chance of passing on the condition to each of his/her children. The chances that a child who has the gene mutation associated with HDD will develop a desmoid tumor are thought to be very high, maybe even 100%. It is possible that there may be other genes involved in HDD, but no gene other than APC has been identified. The location of the mutation within the APC gene may predict the symptoms and health problems that a person will experience, but this association is far from perfect.
Demographics
Hereditary desmoid disease is a rare condition. As of 2001, only four families have been reported in the medical literature. (It is likely, however, that not all families with HDD have been described in the literature.) Males and females are equally affected.
Signs and symptoms
Desmoid tumors may cause a noticeable lump and/or pain.
Diagnosis
HDD is usually diagnosed solely upon family history. Evaluation for HDD requires filling out a detailed, three-generation family tree. Medical records and/or death certificates should also be examined to confirm or clarify possible diagnoses of desmoid tumors. Medical records for family members developing colon polyps and/or undergoing colon surgery will also be requested in order to evaluate for FAP.
Genetic (or diagnostic) testing for APC gene mutations (changes) is another way of making a diagnosis. It may be offered to someone who has developed a desmoid tumor and has a family history of such tumors. If a mutation is identified, the positive test result provides proof of the diagnosis. If no mutation is identified, this negative
test result does not necessary remove the diagnosis of HDD.
Diagnostic testing for HDD may be offered to an individual who has no personal history of a desmoid tumor but whose family history is strongly suggestive of HDD. Prenatal diagnosis of HDD is available only if an APC genetic alteration has already been identified in the family. Such "predictive"genetic testing is best done with a geneticist (a doctor specializing in genetics) and/or a genetic counselor.
Treatment and management
There is no cure for HDD, nor a method for preventing it. Treatment depends upon the location of the tumor and may include one or more of the following: surgery, chemotherapy, hormonal therapy, and/or radiation. In addition, everyone diagnosed with a desmoid tumor should be evaluated for FAP. This evaluation will include a detailed family history as well as colon screening though sigmoidoscopy or colonoscopy.
Treatment is not required until a tumor develops. Someone who has symptoms, however, must have regular medical check-ups.
There are no proven methods of screening for or preventing desmoid tumors, but it is suggested that people with or at risk for HDD have physical examinations every year. It is very important that an individual's physician be aware of the family history and the risk of developing a tumor.
Prognosis
An individual who has a genetic mutation for HDD has a high chance of developing a desmoid tumor. However, the condition is treatable. Prognosis may be affected by a person's overall condition, so being healthy and engaging in healthy behaviors increase the chances of a good outcome.
National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. <http://www.rarediseases.org>.
