The nevoid basal cell carcinoma syndrome (NBCCS) is a rare, complex genetic disorder characterized by a wide variety of developmental abnormalities and a predisposition to developing certain forms of cancer, particularly a type of skin cancer known as basal cell carcinoma. The specific symptoms and severity of NBCCS can vary greatly from one individual to another, even among members of the same family. Multiple organ systems can become involved. Common symptoms include multiple basal cell carcinomas, recurrent keratocystic odontogenic tumors of the jaws, pits of the palms and soles, and skeletal malformations. Some affected individuals may have distinctive facial features. The onset of specific symptoms can vary occurring anywhere from infancy through adulthood. NBCCS is caused by mutations in the PTCH1 gene and is inherited as an autosomal dominant trait, but a significant fraction of cases are sporadic (due to new mutations) with no previous family history.
In 1894, the first patients with NBCCS were described in the medical literature by two different doctors. However, it was not until 1960 that two physicians (Drs. Robert Gorlin and Robert Goltz) wrote the first in-depth description of NBCCS as a distinct clinical entity. Consequently, the disorder is also known as Gorlin syndrome or Gorlin-Goltz syndrome. Over the years, case reports and series have continued to expand the range of symptoms and physical findings that can be associated with NBCCS, and there are now more than 100 different recognized features.
As stated above, NBCCS can potentially affect multiple organ systems in the body. However, it is important to note that affected individuals will not usually develop all of the symptoms discussed below. The severity of NBCCS can vary, and some individuals with mild forms can go undiagnosed, while others can have significant complications. Affected individuals and parents of affected children should talk to their physician and medical team about their specific case, associated symptoms, and overall prognosis.
Some clinicians break down the symptoms into major and minor categories. Major categories include basal cell carcinomas, keratocystic odontogenic tumors, multiple distinctive palmar pits, and calcification of the structures in the brain including the dura mater, the outermost layer of the three membranes that cover the brain and spinal cord.
Many affected individuals will develop basal cell carcinomas, a type of skin cancer. BCCs may appear as brownish, flesh-colored, or orange spots on the skin. They can also appear as red patches of skin or scars. In some cases, BCCs will be small growths or bumps (nodules), while in other cases they may be flat or nearly flat. The number of BCCs that can develop ranges from only a few spots to thousands of tiny lesions. These lesions can vary in size from less than 1 millimeter to approximately 10 millimeters. BCCs do not usually spread to other areas of the body, but they can become aggressive and invade local tissue. Localized infection can develop and these lesions can crust, bleed and ulcerate. Sun-exposed areas of the skin are affected more often than areas that are not commonly exposed to the sun. The face, nape of the neck, back, and chest are most commonly affected. If left untreated BCCs can cause disfigurement, especially if located on the face.
BCCs usually develop between puberty and the mid-30s, but can occur at almost any age. Cases have been reported in children as young as 2 years of age. At least one case was reported where BCCs did not develop until after 50 years of age. Approximately 10% of individuals with NBCCS, especially those with dark skin and limited sunlight exposure, do not develop any BCCs.
Keratocystic odontogenic tumors, also known as odontogenic keratocytes or jaw cysts, are growths that develop in the jaw bones, usually in the lower jaw bone (mandible). Affected individuals usually develop multiple, recurrent cysts. These growths can develop as painless swellings in the jaws, but are often aggressive, progressing to cause pain, fractures, loose teeth or displacement of developing permanent teeth. The alignment of the jaw can be affected. There is a high recurrence rate. Because of their aggressive nature, prompt treatment is recommended. If left untreated, they can potentially damage large portions of the jaw. Keratocystic odontogenic tumors usually appear in the first or second decade of life and have been reported in children as young as 5 years of age. Although their peak occurrence is during the second decade of life, these cysts can occur throughout an affected individual’s life. These cysts are often the first presenting sign in many individuals.
Some individuals may develop hardening (calcification) of certain areas of the central nervous system such as the falx cerebri, which is the structure that divides the two hemispheres (cerebrum) of the brain. The falx cerebri consists of the dura mater, which is the outermost layer of the three membranes covering the brain. Other areas of the central nervous system may be affected as well. Abnormal calcification of structures within the central nervous system affects approximately 90% of affected individuals by the age of 20. This clinical finding is usually not associated with any symptoms.
Affected individuals may develop multiple distinctive small pits on the palms of the hands and the soles of the feet (palmar-plantar pits). These pits are usually only 1-2 millimeters in size. They can be seen much more clearly after soaking the hands or feet in warm water for approximately 10 minutes. Affected individuals may also develop skin tags, which are common, soft small growths that hang off the skin. Individuals with NBCCS tend to develop more skin tags than would normally be seen. These growths are benign and painless, although they can be irritated by friction (e.g. clothes rubbing against them). Small, bumps (epidermal cysts) are also common findings, usually found on the limbs and trunks.
At birth, infants may display certain characteristic features including macrocephaly, a condition characterized by a head circumference larger than would normally be expected based upon a child’s age and height. Additional early distinctive features include a bulging forehead (frontal bossing), widely spaced eyes (hypertelorism), tiny white bumps or cysts on the skin (facial milia) and coarse facial features. Facial milia are most often found below the eyes or on the forehead. In rare cases, affected individuals may develop cleft palate or cleft lip or additional eye abnormalities including abnormally small eyes (microphthalmia), cataracts, rapid involuntary eye movements (nystagmus), and a partial absence of tissue from the iris or retina (coloboma). Crossed eyes (strabismus), which are common in the general population, occur a bit more frequently in NBCCS. The eyes may appear sunken due to frontal bossing.
A variety of skeletal abnormalities may be associated with NBCCS including fused, splayed or missing ribs, abnormal curvature of the spine (scoliosis), extra fingers or toes (polydactyly), webbing of the fingers or toes (syndactyly), and Sprengel deformity, a condition characterized by elevation and/or underdevelopment of the shoulder blade (scapula), limited movement of the arm on the affected side, and the development of a lump at the base of the neck due to elevation of the shoulder blade. Affected individuals may exhibit a sunken chest (pectus carinatum) or a chest that protrudes outward (pectus excavatum). In some cases, individuals may have spina bifida, a condition characterized by a malformation of the spinal column in which incomplete closure of certain vertebrae leaves a portion of the spinal cord exposed. Individuals with NBCSS generally have a mild form of spinal bifida, which may not be associated with symptoms, but can be associated with hydrocephalus in rare cases. Hydrocephalus is a condition in which accumulation of excess cerebrospinal fluid in the skull causes pressure on the brain.
Approximately 5% of affected individuals develop a medulloblastoma, the most common type of malignant brain tumor in children. Medulloblastomas occur in the cerebellum, the part of the brain located at the base of the skull just above the brainstem. The cerebellum is involved in many functions including coordination of voluntary movements and regulating balance and posture. Symptoms associated with a medulloblastoma can include headaches in the morning that improve as the day goes on, recurrent vomiting and difficulty walking and with balance. Medulloblastomas can spread to affect other areas of the central nervous system. Medulloblastomas associated with NBCCS tend to occur around the age of 2, younger than in children without NBCCS (isolated medulloblastoma). In addition, when associated with NBCCS, this tumor is generally less aggressive than the isolated form. In most cases, the desmoplastic subtype of medulloblastoma develops. Medulloblastomas in NBCCS are more common in males than females by a ratio of approximately 3:1. (For more information on this disorder, choose “medulloblastoma” as your search term in the Rare Disease Database.)
Individuals with NBCCS are at risk of developing additional tumors including cardiac or ovarian fibromas. Fibromas are benign tumors consisting of connective tissue. Cardiac fibromas are present at birth or shortly thereafter. These growths may not cause symptoms or they can cause irregular heartbeats (arrhythmias) or obstruct blood flow. Affected females may develop ovarian fibromas. These growths may not cause any symptoms unless they become large and calcified, potentially causing twisting (torsion) of the ovaries. Ovarian fibromas are not thought to affect fertility.
Additional tumors can develop including tumors that arise from the membranes (meninges) that line the brain and spinal cord (meningiomas), tumors of the muscles attached to the bone (rhabdomyosarcoma), and a benign tumor normally located inside the heart (rhabdomyomoma). Other brain tumors have been reported individuals with NBCCS, but may occur secondary to radiation therapy.
Males with NBCCS may develop diminished hormone production from the testes (hypogonadotrophic hypogonadism), abnormally enlarged breasts (gynecomostia), and a female pattern of pubic hair distribution.
Cysts or polyps can form in various parts of the body including the bones, airway passages (bronchi), intestines, and the fold of tissue of the peritoneum that supports and attaches the intestines to the wall of the abdomen (mesentery). The peritoneum is the membrane that lines the abdominal cavity. Mesenteric cysts are common and usually do not produce symptoms. Cysts on the brain have been found as well.
Additional symptoms and physical findings have been reported in individuals with NBCCS. These symptoms may include intellectual disability, seizures, middle ear anomalies, minor kidney abnormalities, absence of the internal carotid artery, an impaired ability to smell (anosmia), and hardening of the skin due to the accumulation of calcium deposits underneath the skin. Intellectual disability is unusual in patients with mutations limited to the PTCH1 gene and is often related to deletions or other chromosome rearrangements that affect PTCH1 along with surrounding genes.
Various other forms of cancer have been reported to occur in individuals with NBCCS. However, it is unknown whether affected individuals have a predisposition to developing these cancers or whether their development is coincidental (i.e. independent of the disorder). More research is necessary to determine what forms of cancer are related to NBCCS and which forms are chance occurrences.
Nearly all cases of NBCCS have been caused by a mutation in the PTCH1 gene. Genes provide instructions for creating proteins that play a critical role in many functions of the body. When a mutation of a gene occurs, the protein product may be faulty, inefficient, or absent. Depending upon the functions of the particular protein, this can affect many organ systems of the body.
In cases without a positive family history of the disorder, the PTCH1 gene mutation may occur spontaneously for no apparent reason (sporadically) representing a new mutation. Approximately 35-50% of cases represent a new mutation. In cases with a positive family history, the mutation is inherited as an autosomal dominant trait.
Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
NBCCS is characterized by complete penetrance, which means that all individuals who inherit the gene for a dominant disorder will develop symptoms of the disorder. NBCCS is also characterized by variable expressivity, which means that widely varying signs and symptoms can occur among affected individuals.
Investigators have determined that the PTCH1 gene is located on the long arm (q) of chromosome 9 (9q22.3- q31). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 9q22.3-q3″ refers to bands 22.3-31 on the long arm of chromosome 9. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Researchers believe that the PTCH1 gene is as a tumor suppressor gene. A tumor suppressor gene is a gene that slows down cell division, repairs damage to the DNA of cells, and/or tells cells when to die, a normal process called apoptosis. The PTCH1 gene creates (encodes) a protein that is involved in the sonic hedgehog pathway. This pathway involves a number of complex interactions that are critical for normal human development. These interactions involve the activation or repression of certain other genes. Impairment (dysregulation) of this pathway leads to human disease including cancer.
Mutation of one of an individual’s two copies of the PTCH1 gene is believed to be sufficient to cause many of the developmental abnormalities associated with NBCCS such as rib/vertebrae abnormalities or macrocephaly. However, cancer development in affected individuals is believed to follow the “two-hit” theory. This theory states that a second hit, damage to the normal copy of the PTCH1 gene, is required before cancer can develop. This second hit can occur at any point after conception (somatically).
Exposure to ultraviolet light appears to play a role in the development of BCCs in individuals with NBCCS. BCCs are much more common in sun-exposed areas of the skin and more common in Caucasian individuals than individuals of African American descent. Additionally, individuals with NBCCS are particularly prone to develop BCCs in areas of the body exposed to high levels of ionizing radiation, such as radiation therapy. There is no evidence linking diagnostic X-rays to an increased risk of BCCs.
The exact prevalence of NBCCS is unknown. The figure most quoted in the medical literature is 1 individual per 57,000 people in the general population. This figure was based upon a population study in the United Kingdom. However, the authors of that study have revised that figure to approximately 1 in 30,000. The true prevalence of NBCCS in the general population may actually be higher because cases, especially mild ones, can go undiagnosed or misdiagnosed. NBCCS affects males and females in equal numbers. Basal cell carcinoma of the skin (including isolated cases not associated with NBCCS) is the most common form of cancer in humans.
A diagnosis of NBCCS is based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests. Most medical sources cite that the presence of specific clinical symptoms is sufficient for a diagnosis of NBCCS. These symptoms are grouped into major and minor categories. The specific number of major or minor criteria required for a diagnosis can vary based upon different sources. One commonly used diagnostic set of criteria for NBCCS involves the identification of two major and one minor diagnostic criteria or one major and three minor diagnostic criteria from the list below.
Major criteria include,
1.Calcification of the falx cerebri
2.Keratocystic odontogenic tumor
3.Two or more palmar or plantar pits
4.Multiple BCCs or a BCC before the age of 30
5.First degree relative with NBCCS
Minor criteria include,
2.Various ocular anomalies
3.Radiographic abnormalities of the ribs/vertebrae
6.Mesenteric or pleural cysts
7.Ovarian or cardiac fibromas
Clinical Testing and Workup
Specialized imaging techniques can aid in obtaining a diagnosis of NBCCS. Such tests can include magnetic resonance imaging (MRI), abdominal ultrasound, a skeletal survey, and x-rays of the teeth and jaw. An MRI uses a magnetic field and radio waves to produce cross-sectional images of particular organs and bodily tissues. An MRI of the brain can reveal calcification of the falx cerebri or other structures. An abdominal ultrasound uses reflected sound waves to create an image of the abdomen and can reveal mesenteric cysts. A skeletal survey is a series of x-rays taken of bones all over the body. For example, an anteroposterior (AP) x-ray of the skull can reveal calcification of the falx cerebri.
An echocardiogram may be performed to check for cardiac fibromas. During an echocardiogram, sound waves are bounced off the heart enabling physicians to study cardiac function and motion. An ovarian ultrasound may be performed to check for ovarian fibromas.
A diagnosis of NBCCS can be confirmed through molecular genetic testing, which can detect mutations in the PTCH1 gene that is known to cause NBCCS. Molecular genetic testing is available on a clinical basis.
The treatment of NBCCS is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, dermatologists, oral surgeons, dentists, cardiologists, ophthalmologists, plastic surgeons, and other healthcare professionals may need to systematically and comprehensively plan an affect child’s treatment. Genetic counseling will be of benefit for affected individuals and their families.
Specific therapeutic procedures and interventions may vary, depending upon numerous factors, such as disease severity; tumor size; the presence or absence of certain symptoms; an individual’s age and general health; and/or other elements. Decisions concerning the use of particular therapies or procedures should be made by physicians and other members of the health care team in careful consultation with the patient based upon the specifics of his or her case; a thorough discussion of the potential benefits and risks, including possible side effects and long-term effects; patient preference; and other appropriate factors.
Odontogenic keratocysts usually require prompt surgical removal (excision). The goal of this therapy is to preserve as much of the jaw and teeth as possible because affected individuals often develop multiple cysts throughout adolescence and adulthood. With larger cysts, it is recommended that they be decompressed first, usually through the insertion of a small tube that allows water or saline solution to flush out the tumor, shrinking it in size.
A wide variety of treatment options exist for individuals with BCCs including topical chemotherapy, surgery, drug therapy, cryotherapy, electrodessication and curettage, and photodynamic therapy.
Topical chemotherapy involves the application of creams applied directly to the lesion. Two common topical medications used to treat NBCCS are 5-fluorouracil and imiquimod 5%. These treatments may be used alone or in conjunction with other therapies. 5-fluorouracil works by destroying the abnormal skin cells and may be used to treat small, superficial BCCs in low risk areas. The U.S. Food and Drug Administration (FDA) has approved the use of imiquimod 5% (Aldara®) topical cream for the treatment of superficial basal cell carcinoma.
Many individuals with NBCCS opt for surgical removal lesions if the overall number of lesions is low. Straightforward surgical removal of a lesion involves cutting the lesion out and closing the wound with sutures. In certain cases, large lesions may require a skin graft from another area of the body. Surgical excision of a lesion can result in a scar. Recurrence is possible as well.
A specific type of surgery called Mohs micrographic surgery may be recommended for some individuals with NBCCS. With this surgery, a surgeon uses a precise technique to remove diseased tissue one layer at a time. According to the medical literature, Mohs surgery has proven particularly effective in treating NBCCS and is useful for treating difficult tumors that may not respond to other standard treatments.
The FDA has also approved a drug known as vismodegib (Erivedge®) for the treatment of adults with advanced basal cell carcinoma that has spread to other parts of the body or that has recurred following surgery. Individuals with advanced basal cell carcinoma who are not candidates for surgery or radiation therapy are also approved for this therapy. Erivedge is a capsule taken orally once-a-day. This drug is a targeted therapy (see Investigational Therapies section below).
Cryotherapy may also be used to treat NBCCS. Cryotherapy is the use of extreme cold to freeze and destroy the tissue and cells of skin lesions and is a minimally invasive treatment option. With cryotherapy a freezing substance such as liquid nitrogen or argon gas is applied directly to the lesion. Cryotherapy is most effective for single or small lesions.
Another surgical procedure used to treat individuals with NBCCS is electrodessication and curettage. With curettage, the lesion is scraped off the skin with a surgical instrument called a curette. The procedure is usually performed under anesthesia. In some cases, curettage may be followed by the use of an electrosurgical needle to apply heat and dry up the remaining cancerous tissue (electrodessication). This procedure may need to be repeated in some cases and will often leave a small white scar. This procedure is best for the treatment of small BCCs located in areas where the risk of recurrence is low. Electrodessication and curettage is often used as an alternative to topical chemotherapy.
Laser vaporization is a newer procedure that is sometimes used alone or with curettage to treat BCCs, specifically cases with multiple or superficial lesions. This procedure involves the use of a carbon dioxide laser to destroy (vaporize) abnormal tissue.
Photodynamic therapy, a procedure in which a drug known as a photosensitizer is used along with a special type light, has been used to treat some individuals with NBCCS who have large lesions. During photodynamic therapy, the drug is administered to an affected individual and absorbed by the affected cells. A specific wavelength of light is used to activate the drug which binds with oxygen creating a chemical that destroys the affected cells.
In the past, x-ray or radiation therapy (radiotherapy) was often used to treat individuals with NBCCS, especially individuals who were poor candidates for surgery or who had multiple lesions. Although radiotherapy was effective, researchers have determined that this therapy can actually cause new BCCs to form in the treated areas. Because of this significant adverse side effect, radiotherapy is rarely considered anymore for the treatment of NBCCS.
Affected individuals are encouraged to avoid excess exposure to the sun and to take proper precautions when in the sun (e.g. using sunscreen, sunglasses). Exposure to therapeutic levels of ionizing radiation should be avoided.
Affected individuals should receive a panoramic radiograph once a year from the age of 8. A panoramic radiograph is a specialized x-ray that allows physicians to assess the health of the jaws and surrounding areas such as the nasal cavity. These tests can detect keratocystic odontogenic tumors of the jaw.
Head circumference should be monitored throughout childhood. Any rapid enlargement should prompt an evaluation for hydrocephalus. Physical examination and assessment for a medulloblastoma during childhood is recommended.
Targeted therapies are being studied for the treatment of individuals with NBCCS. Targeted therapies are drugs and other substances that prevent the growth and spread of cancer by blocking or inhibiting certain specific molecules (often proteins) that are involved in the development of specific cancers (these proteins are produced by mutated genes). Generally, targeted therapies are less toxic than other treatments for cancer.
Some individuals with NBCCS have been treated with drugs known as retinoids. These drugs are synthetic versions of vitamin A. Retinoid therapy has caused regression of small lesions and help to prevent new lesions in some cases. However, this has required very large doses that are often associated with significant side effects and toxicity.
A drug known as interferon has been used to treat individuals with NBCCS. Interferon is a type of immunotherapy. Immunotherapy is the enhancement or suppression of the body’s natural immune system to fight disease such as cancer. In some cases, treatment with interferon has led to complete resolution of BCCs; in other cases it was less effective.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, in the main, contact:
For more information about clinical trials conducted in Europe, contact: https://www.clinicaltrialsregister.eu/
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