What Is Basal Cell Naevus Syndrome?

Basal cell naevus syndrome, also widely known as Gorlin syndrome, is a rare genetic cancer condition that affects multiple parts of the body. The name might sound complex, but it essentially describes a syndrome where people develop numerous basal cell carcinomas, which are cancerous growths in the outer layer of skin. Unlike typical skin cancer that develops in older adults after decades of sun exposure, people with this syndrome start developing these cancers much earlier—often before the age of 20^[1].

The syndrome doesn’t stop at skin problems. It also causes noncancerous growths called odontogenic keratocysts in the jawbones, distinctive physical features, and skeletal differences. Some people with basal cell naevus syndrome experience only mild symptoms, while others face more serious complications. The condition affects the skin, bones, nervous system, and sometimes internal organs, making it a complex disorder that requires lifelong monitoring^[2].

This syndrome is also called by several other names, including naevoid basal cell carcinoma syndrome, Gorlin-Goltz syndrome, and basal cell carcinoma syndrome. These different names all refer to the same genetic condition. The syndrome was described in detail by Dr. Robert Gorlin in 1960, which is why his name became permanently attached to it^[4].

How Common Is Basal Cell Naevus Syndrome?

Basal cell naevus syndrome is quite rare. Medical experts estimate that it affects somewhere between 1 in 40,000 to 1 in 256,000 people worldwide, depending on which study you look at. One commonly cited prevalence is about 1 in 60,000 individuals^[2][4]. These numbers might seem vague, but that’s because the actual number of people with this syndrome is difficult to pin down. Some people have such mild symptoms that they never get diagnosed, so the true number could be higher than estimates suggest^[1].

The syndrome affects males and females in roughly equal numbers. While it appears in all racial and ethnic groups, there are interesting differences in how often it’s diagnosed and how it presents. The syndrome is much more commonly diagnosed in people with pale skin. In fact, among Black Americans and Asians, Gorlin syndrome is diagnosed far less frequently—these groups represent only about 5% of all cases^[2][10].

This doesn’t necessarily mean that people with darker skin don’t carry the genetic mutation. Instead, they tend to develop fewer skin cancers or different features of the syndrome. About 80 to 90 percent of pale-skinned patients with Gorlin syndrome develop basal cell carcinomas, but Black patients may have fewer than two skin cancers throughout their lives, and roughly 20% of dark-skinned Africans with the syndrome never develop any skin cancers at all^[1][11]. When people with darker skin are diagnosed with the syndrome, it’s often because they develop jaw cysts or other non-skin features first.

What Causes Basal Cell Naevus Syndrome?

Basal cell naevus syndrome happens because of changes, or mutations, in certain genes that normally protect the body from developing tumors. These genes are called tumor suppressor genes, and their job is to keep cells growing and dividing in an orderly, controlled way. When these genes don’t work properly, cells can grow abnormally and form tumors^[2].

The main gene involved is called PTCH1, located on chromosome 9. This gene creates a protein that acts like a receptor on the cell surface, receiving signals from a pathway known as the sonic hedgehog signaling pathway. This pathway is crucial during development because it helps cells know how to grow, divide, and become specialized. When PTCH1 is mutated, the pathway doesn’t function correctly, leading to the formation of multiple tumors and the various features seen in the syndrome^[1][2].

Two other genes can also cause the syndrome, though they’re much less common. These are PTCH2 on chromosome 1 and SUFU on chromosome 10. People with mutations in SUFU face a particularly high risk—they have about a 20-fold increased chance of developing a serious childhood brain tumor called medulloblastoma compared to those with PTCH1 mutations^[2][10].

The syndrome follows what geneticists call an autosomal dominant pattern of inheritance. This means that if one parent carries the mutated gene, each of their children has a 50% chance of inheriting it and developing the condition. You only need one copy of the mutated gene to have the syndrome—you don’t need to inherit it from both parents^[1][3].

Scientists believe that people with basal cell naevus syndrome are born with one defective copy of the PTCH1 gene in all their cells. This is called the first “hit.” For cancer or tumors to actually develop, a second mutation must occur in the remaining normal copy of the gene in certain cells. This second “hit” can come from environmental factors like ultraviolet (UV) light from the sun or ionizing radiation. When both copies of the gene are damaged in a cell, that cell loses its ability to control growth, and a tumor can form^[2][14].

Who Is at Risk for Basal Cell Naevus Syndrome?

The biggest risk factor for basal cell naevus syndrome is having a family history of the condition. If one of your parents has the syndrome, you have a 50% chance of inheriting the genetic mutation. Even if a parent shows only mild symptoms—perhaps just a few jaw cysts or palmar pits—they can still pass the full genetic mutation to their children, who might develop more severe features^[3][15].

Because the syndrome shows variable expressivity, family members with the same mutation can have very different experiences. One person might develop hundreds of skin cancers and require frequent surgeries, while their sibling with the same mutation might have only a few basal cell carcinomas and some skeletal differences. This variability can make the syndrome seem to “skip” generations, but the genetic mutation is still being passed along^[4].

People with pale skin face higher risks of developing the skin cancer features of the syndrome compared to those with darker skin. Fair-skinned individuals, especially those with blond or red hair and blue, green, or grey eyes, are more likely to develop numerous basal cell carcinomas. This doesn’t mean that people with darker skin don’t have the syndrome—they simply tend to develop other features of it, like jaw cysts or skeletal changes, rather than skin cancers^[1][11].

Environmental factors also play a role once someone has the genetic mutation. Excessive exposure to UV radiation from sunlight or tanning beds can trigger the “second hit” needed for basal cell carcinomas to form. Radiation therapy used to treat other medical conditions can also increase the risk. This is why people with basal cell naevus syndrome must be extremely careful about sun protection throughout their lives^[2][10].

What Are the Symptoms and Signs?

The symptoms of basal cell naevus syndrome vary greatly from person to person, but there are several hallmark features that doctors look for when making a diagnosis. The most recognizable sign is the development of multiple basal cell carcinomas starting at a young age.

Skin Features

Multiple basal cell carcinomas are the defining feature of this syndrome. These skin cancers usually start appearing during the teenage years or early twenties, though they can develop in childhood in some cases. Unlike typical basal cell carcinoma that appears in people over 45 after years of sun damage, these cancers come early and in large numbers^[1][2].

The cancers most commonly appear on sun-exposed areas like the face, scalp, neck, and back, but they can also develop in unusual locations that rarely see sunlight, such as the genitalia or the palms of the hands. They appear as smooth, rounded bumps that can range from 1 to 15 millimeters in diameter. Some look like small skin tags, moles, tiny blood vessel growths, or white bumps called milia. Others may be shiny with a pearly appearance and visible tiny blood vessels on the surface^[1][11].

Another very common skin feature is the presence of small pits or indentations in the palms of the hands and soles of the feet. These are called palmoplantar pits, and they appear in up to 87% of people with the syndrome. The pits often develop during childhood and are permanent. They look like tiny puncture marks scattered across the palms and soles^[1][4].

People with the syndrome may also develop milia and epidermoid cysts—small, benign bumps under the skin. Some individuals have webbing between their fingers or toes^[1][11].

Jaw and Dental Features

Odontogenic keratocysts are fluid-filled growths that develop inside the jawbone. They’re present in 65 to 80 percent of people with basal cell naevus syndrome and are often the earliest sign of the condition, sometimes appearing before skin cancers develop^[1][4].

These cysts usually appear during the second or third decade of life—in other words, during the teenage years and twenties. Most are located in the lower jaw (mandible), though they can occur in the upper jaw as well. The cysts are often painless, so people may not know they have them until a dental X-ray or examination reveals their presence^[1][11].

When the cysts grow large, they can cause noticeable problems. The face may become swollen, teeth may shift position or become displaced, and in severe cases, the cysts can cause the jawbone to fracture. Some people lose teeth or have teeth that don’t erupt properly^[4][13].

Skeletal and Physical Features

Many people with basal cell naevus syndrome have distinctive facial features that become more apparent as they grow. These can include a larger-than-average head size (macrocephaly), a prominent forehead and sides of the head (called frontal and parietal bossing), widely spaced eyes (hypertelorism), a broad nasal bridge, and a protruding lower jaw^[1][4].

Skeletal abnormalities affect about 65 to 70 percent of people with the syndrome. The most common are rib abnormalities—ribs may be split (bifid), fused together, or splayed out. Some people have spinal curvature issues like scoliosis (sideways curve) or kyphoscoliosis (combined forward and sideways curve), or wedge-shaped vertebrae. Other possible skeletal features include extra fingers or toes (polydactyly), fused fingers or toes (syndactyly), sunken chest (pectus excavatum), or protruding chest (pectus carinatum)^[1][11][4].

In some cases, people have cleft lip and palate, a high arched palate inside the mouth, or incomplete formation of the spine (spina bifida)^[1][11].

Other Tumors and Growths

People with basal cell naevus syndrome have increased risks for developing other types of tumors beyond skin cancers. Medulloblastoma is a cancerous brain tumor that can develop in childhood. It occurs in about 5% of people with the syndrome, and those with SUFU gene mutations face a 20-fold higher risk than those with PTCH1 mutations. However, it’s worth noting that only about 3% of all children who develop medulloblastoma have basal cell naevus syndrome^[1][2][11].

Noncancerous tumors called fibromas can develop in various parts of the body. Cardiac fibromas—benign tumors in the heart—occur in about 2% of children with the syndrome. Ovarian fibromas develop in about 20% of females with the condition; these are usually on both sides and may contain calcium deposits. Other possible tumors include meningiomas (usually benign brain or spinal cord tumors) and rhabdomyosarcomas (cancerous muscle tumors)^[1][4][11].

Other Features

A distinctive finding seen on imaging studies is calcification of a structure in the brain called the falx cerebri. This happens in about 65 to 90 percent of people with the syndrome by age 20. The falx cerebri is a fold of tissue that separates the two halves of the brain, and calcium deposits there show up clearly on skull X-rays or CT scans^[1][4][11].

Eye problems can occur, including cataracts, glaucoma, crossed eyes (strabismus), cloudiness of the cornea, changes in retinal pigmentation, and in rare cases, congenital blindness^[1][11].

Males with the syndrome may develop enlarged breast tissue (gynaecomastia) or have underdeveloped testes (hypogonadism). Females may have an abnormally shaped uterus (bicornuate uterus). Some people develop lymphatic cysts in the tissue that supports the intestines (mesentery). About 5% of people with the syndrome have some degree of intellectual impairment^[1][11].

How Is Basal Cell Naevus Syndrome Prevented?

Because basal cell naevus syndrome is a genetic condition that people are born with, there’s no way to prevent the syndrome itself. However, there are important steps that people with the syndrome can take to prevent or minimize complications, especially the development of numerous skin cancers.

Sun protection is absolutely critical for anyone with basal cell naevus syndrome. UV radiation from sunlight triggers the “second hit” mutations needed for basal cell carcinomas to form, so protecting the skin from sun exposure throughout life can significantly reduce the number of skin cancers that develop. This means using broad-spectrum sunscreen with high SPF every day, wearing protective clothing including wide-brimmed hats and long sleeves, seeking shade during peak sun hours, and avoiding tanning beds completely^[14][6].

People with the syndrome should also avoid unnecessary exposure to ionizing radiation. This can be tricky because radiation is sometimes used in medical imaging (like X-rays and CT scans) and in cancer treatment. Doctors caring for people with basal cell naevus syndrome should carefully weigh the benefits and risks of any procedure involving radiation and use alternative imaging methods like ultrasound or MRI when possible^[2][10].

Regular screening and monitoring are forms of secondary prevention that catch problems early when they’re most treatable. Children with the syndrome should have their first brain MRI scan between ages 1 and 2 to screen for medulloblastoma, followed by regular MRI scans until about age 8. Dental examinations and jaw imaging starting in childhood can catch odontogenic keratocysts early. Regular full-body skin examinations—at least every six months for adults—allow doctors to detect new basal cell carcinomas when they’re small and easier to treat^[1][11].

Women with the syndrome should have regular pelvic ultrasounds to monitor for ovarian fibromas. Genetic counseling is valuable for families affected by the syndrome, helping them understand inheritance patterns and make informed decisions about family planning^[2][4].

Understanding How the Syndrome Affects the Body

At the most basic level, basal cell naevus syndrome changes how cells in the body grow and develop. The sonic hedgehog signaling pathway, which is disrupted by mutations in PTCH1, PTCH2, or SUFU genes, normally acts like a cellular communication system. It tells cells when to grow, when to stop growing, when to divide to make more cells, and what type of specialized cell to become^[1][2].

The PTCH1 gene creates a protein that sits on the surface of cells and acts like a brake on the sonic hedgehog pathway. When this brake is working properly, it keeps cell growth under control. But when someone inherits a mutated copy of PTCH1, the brake doesn’t work as well. If the second copy also becomes damaged—from sun exposure, for example—the brake fails completely in that cell. Without proper braking, the sonic hedgehog pathway stays active when it shouldn’t be, telling cells to keep growing and dividing when they should stop. This uncontrolled growth leads to tumor formation^[2][10].

During fetal development, the sonic hedgehog pathway plays crucial roles in forming many body structures. This explains why people with basal cell naevus syndrome often have skeletal differences, distinctive facial features, and developmental variations. The pathway helps guide how bones form, how the face takes shape, and how the nervous system develops. When the pathway doesn’t function properly, these structures may develop differently, leading to the characteristic features of the syndrome^[1].

The process of forming basal cell carcinomas requires multiple mutations in different growth control genes. Loss of both copies of PTCH1 is just the first step. Additional random mutations must accumulate in a cell before it becomes fully cancerous. This is why even people with the genetic mutation don’t develop cancer immediately at birth—it takes time for those additional mutations to occur. Environmental factors like UV exposure speed up this process by causing DNA damage that leads to more mutations^[2][10].

The jaw cysts that develop in basal cell naevus syndrome form when cells lining developing teeth grow abnormally. These odontogenic keratocysts are lined with a specific type of tissue and filled with a protein called keratin. They have a tendency to recur after surgical removal because the cells lining them can be left behind and grow again^[1][11].

When medulloblastomas develop in children with the syndrome, they form in the cerebellum, the part of the brain that controls balance and coordination. These tumors grow from primitive nerve cells that haven’t finished developing properly. The syndrome doesn’t cause these brain tumors to develop in everyone—the risk is about 5%—but when they do occur, they typically appear during childhood rather than adulthood^[1][2][11].