What is nevoid basal cell carcinoma syndrome?
Nevoid basal cell carcinoma syndrome is a condition that affects many areas of the body. People with this syndrome have a higher risk of developing certain kinds of tumors. These tumors can be either cancerous (malignant) or non-cancerous (benign). Tumors may develop in these areas:
People with nevoid basal cell carcinoma syndrome may also have some or all of the following:
- Small pits in the palms of the hands or soles of the feet
- Large head size (macrocephaly), sometimes caused by too much fluid in the brain (hydrocephalus)
- Distinct facial features, such as wide-set eyes, a jaw that juts out and a prominent forehead
- Tiny white cysts (bumps), called milia, around the cheeks, eyes and lips
- Defects in the ribs and spine
- Extra fingers and toes
- Eye conditions, such as cataracts, “lazy” eye, a very small eyeball or missing structures in the eye
- Cleft lip
- Cleft palate
- Mental disability or learning disorder
Most people with nevoid basal cell carcinoma syndrome have only some of these features.
What is the tumor risk for children with nevoid basal cell carcinoma syndrome?
People with nevoid basal cell carcinoma syndrome are at higher risk for the following cancerous tumors:
- Medulloblastoma, a brain tumor that occurs in children
- Basal cell carcinoma, the most common form of skin cancer
People with nevoid basal cell carcinoma syndrome are at higher risk for the following non-cancerous tumors:
- Painless cysts in the jaw, called jaw keratocysts
- Tumors in the connective tissue of the ovaries and heart, called fibromas
Although people with nevoid basal cell carcinoma syndrome are at higher risk for tumors, some people never develop them. Others might develop many tumors. About 5% of children with nevoid basal cell carcinoma syndrome develop medulloblastoma. This happens most often around 2 years of age. Basal cell carcinomas appear in about 90% of people with the syndrome, usually starting in the teenage years. Jaw cysts occur in about 90% of people with this condition. Most appear in the teenage years, but some can occur in younger children. Fibromas of the heart occur in about 2% of people with nevoid basal cell carcinoma syndrome and are often present at birth. Fibromas of the ovary occur in about 20% of females with the condition.
What causes nevoid basal cell carcinoma syndrome?
Nevoid basal cell carcinoma syndrome is caused by changes in a gene known as PTCH1. Genes carry information telling cells within the body how to function. The PTCH1 gene helps to control how cells grow and divide. It also helps ensure that a pregnancy develops normally, especially the growth of the jaw, skin and brain.
Most people without nevoid basal cell carcinoma syndrome carry two working copies of the PTCH1 gene in their cells. One copy of PTCH1 is inherited from the mother and one from the father. Cells from people with nevoid basal cell carcinoma syndrome carry one working copy of PTCH1 and one copy that is changed. This change causes the gene to not work properly. It is called a PTCH1 mutation.
Most children with nevoid basal cell carcinoma syndrome inherit their PTCH1 mutations from a parent who also has the syndrome. About 20% to 30% of children have a new PTCH1 mutation that did not come from a parent. These children have no history of the syndrome in their family. In these cases, the change either happened in an egg or sperm cell when the child was formed or in one of the child’s cells during pregnancy. These children are the first in their families to have nevoid basal cell carcinoma syndrome. No matter how they acquired the PTCH1 mutation, people with nevoid basal cell carcinoma syndrome have a 50% or 1 in 2 chance of passing it on to their children.
Most people born with one PTCH1 mutation will have some signs and symptoms of the condition in childhood. These can include a large head, distinct facial features or defects in the ribs and spine. During a person’s life, the second copy of the PTCH1 gene might also become changed in one or more cells of the body, such as the skin or brain. When this happens, those cells can develop into a tumor. This is why people with nevoid basal cell carcinoma syndrome have a greater risk of developing tumors such as basal cell carcinomas or medulloblastoma.
How are children with nevoid basal cell carcinoma syndrome screened for tumors?
People with nevoid basal cell carcinoma syndrome should be managed by a doctor who knows this condition well. We recommend screening for anyone with nevoid basal cell carcinoma syndrome, even though not everyone with the syndrome will develop tumors. The goal of screening is finding and treating tumors early to allow the best outcome for patients. It can also prevent the growth of disfiguring tumors that could alter a person’s appearance.
Tumor screenings recommended:
- An echocardiogram during the first year of life to check for fibromas in the heart. An echocardiogram uses sound waves to make images of the heart.
- Magnetic resonance imaging (MRI) of the brain to look for brain tumors. This should be done every year until the person turns 8 years old. If there are any symptoms, the imaging should be repeated more often.
- Digital panoramic X-rays of the jaw to look for cysts. These should begin as soon as the child can handle the procedure and should be repeated yearly. After the first jaw cyst, the X-rays should be repeated every 6 months until there are no jaw cysts for 2 years. At that point, the patient can go back to having the X-rays once a year. X-rays should be repeated more often if the person has symptoms of a jaw cyst or a new cyst is confirmed.
- Yearly skin exams starting from the time of diagnosis to look for basal cell carcinoma. After one or more appear, skin exams should occur at least twice a year.
- Head circumference (size around the head) should be measured at birth and regularly throughout childhood. Any unusual head growth should be followed up right away.
- X-rays or other imaging tests at diagnosis. These can detect problems in the spine, ribs, skull or other bones. More imaging may be done throughout childhood if problems are found. Ideally patients should try to have these screenings at a center that can do digital X-rays.
- Routine developmental screening during yearly well-child exams to check for mental disability or learning disorder. Further testing of development and learning should be done if:
- Screening suggests a problem,
- The child is not meeting typical developmental milestones, or
- The child has trouble learning in school.
- Eye exams at diagnosis to check for eye or vision problems. If symptoms appear, the exams should be repeated.
- In females, an ultrasound of the ovaries should be done before getting pregnant to check for tumors.
These recommendations are the most current. It is possible that what is recommended may change over time as doctors learn more about nevoid basal cell carcinoma syndrome. Because this syndrome is rare and complex, it is important that parents seek out and discuss all screening options for their child with a doctor who works regularly with this syndrome.
How is genetic testing for nevoid basal cell carcinoma done?
The doctor may suspect nevoid basal cell carcinoma syndrome after looking at a person’s medical or family history. In most cases, a doctor or genetic counselor will ask questions about the person’s health and the health of other family members.
The genetic counselor or doctor will record which family members have developed tumors, what types of tumors and at what ages these tumors occurred. From this information they will create a family tree. Doctors and genetic counselors will look at the family tree to find out:
- If there are more cancers than normal,
- If cancers occurred at younger-than-expected ages and
- If the types of tumors match up with what might be seen in those with nevoid basal cell carcinoma syndrome.
If nevoid basal cell carcinoma syndrome is suspected in a child or other family members, the doctor or genetic counselor will likely recommend genetic testing of the PTCH1 gene.
Diagnostic genetic testing
If the doctor or genetic counselor suspects that a person has nevoid basal cell carcinoma syndrome, diagnostic testing may take place as follows:
- A blood sample is collected.
- DNA is isolated from the cells in the sample. A person’s genes are made of DNA.
- Both copies of the person’s PTCH1 gene are checked for possible changes. A genetic specialist compares the two copies of the person’s gene to a normal PTCH1 gene. If there are differences, the specialist decides if they might cause a certain condition such as nevoid basal cell carcinoma syndrome.
- If a PTCH1 mutation is found, the genetic counselor will work with the family in the following ways:
- To help the family understand the cancer and tumor risks of nevoid basal cell carcinoma syndrome
- To find out if other family members should consider testing
- To help with decisions about prenatal genetic testing
Prenatal genetic testing
Parents may undergo prenatal testing to find out if the pregnancy is affected with a known PTCH1 mutation in the family. Testing may take place either before pregnancy occurs or during pregnancy (after the embryo is formed).
Those considering prenatal testing should work with a genetic counselor to review the pros and cons of the tests. The genetic counselor can also help parents consider how they wish to handle the results of the testing.
Testing that occurs before pregnancy — Testing that happens before pregnancy is called preimplantation genetic diagnosis (PGD). This special type of genetic testing is done along with in vitro fertilization (IVF). PGD offers a way to test embryos for a known PTCH1 mutation before placing them into the uterus.
Testing that occurs during pregnancy — Testing can be used to see if a pregnancy is affected with a known PTCH1 mutation. A doctor gathers cells from the pregnancy in one of two ways:
- Chorionic villus sampling (CVS) — during the first trimester (first three months)
- Amniocentesis — during the second trimester or later (last 6 months)
Collected tissue can be checked for the presence of the PTCH1 mutation identified in the family.
Both of these tests carry minor risks and should be discussed with an experienced doctor or genetic counselor.
Genetic testing for nevoid basal cell carcinoma syndrome is a complex process. Those thinking about testing should take time to consider the benefits and risks. They should discuss the process with a genetic counselor before testing is done. If they choose testing, they should review the test results with the doctor or genetic counselor to be sure they understand the meaning of the results.
Sometimes children or adults with nevoid basal cell carcinoma syndrome can feel sad, anxious or angry. Parents who pass on a PTCH1 mutation to one or more of their children can feel guilty. Some people with a PTCH1 mutation could have trouble getting disability coverage, life insurance or long-term care insurance in some states. Read more about genetic discrimination.
Are there other special health care needs for children with nevoid basal cell carcinoma syndrome?
People of any age with nevoid basal cell carcinoma syndrome have a higher risk of cancer. They should monitor their health and adopt healthful habits throughout life. It is important to continue to have regular physical checkups and screenings. That way, any cancer can be found early at the most treatable stage.
It is critical that people with nevoid basal cell carcinoma syndrome avoid exposure to radiation. When X-rays are needed, people should find a center that can do digital X-rays.
People with nevoid basal cell carcinoma syndrome should be careful about sun exposure:
- Avoid sun exposure during the hours of 10 a.m. and 4 p.m.
- Wear protective clothing and a hat
- Use sunscreen with an SPF of at least 30 when going outside
Other ideas for reducing the risk of cancer include the following:
- Eat a healthful diet with lots of fruits and vegetables
- Get regular exercise
- Avoid smoking or using tobacco products
- Avoid secondhand smoke
People with nevoid basal cell carcinoma syndrome should watch closely for general signs or symptoms that could signal tumors:
- Unexplained weight loss
- Loss of appetite
- Aches, pains, lumps or swelling that cannot be explained
- Headaches or changes in vision or nerve function that do not go away
- New moles or changes in moles that are already present
It is important to seek medical help if anything unusual appears.
The St. Jude website is designed for educational purposes only and is not engaged in rendering medical advice or professional services. The information provided through this site should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. If you have or suspect you may have a health problem, you should consult your health care provider.