Frontal Bossing: What Is It?

Frontal bossing refers to an unusually prominent forehead, with a heavier brow ridge seen in some cases.

If your baby has this condition, it may be a sign that they have a rare syndrome. The syndromes associated with frontal bossing can affect the bones, hormones, and stature of your baby.

Causes of Frontal Bossing

The conditions that cause frontal bossing are usually rare. They can be hormonal disorders, genetic or inherited syndromes, or others. 

A common cause of frontal bossing is acromegaly, which is a hormonal disorder caused when the pituitary gland releases too much growth hormone. This excess leads to the bones of the face, skull, jaw, hands, and feet being enlarged.

Several rare genetic conditions may cause frontal bossing; these include the following: 

  • Basal cell nevus syndrome (Gorlin’s syndrome): This condition is characterized by skeletal abnormalities, cysts in the jaw, and carcinomas, a type of cancer.
  • Crouzon syndrome: This condition causes premature fusion of some skull bones.
  • Cleidocranial dysostosis (cleidocranial dysplasia or CCD): This condition affects the teeth, collarbone, spine, skull, and legs. It causes the bones to be fragile, and in some cases, bones like collarbones are absent.
  • Hurler syndrome: This condition leads to skeletal abnormalities, heart disease, respiratory issues, and more.
  • Pfeiffer syndrome: This condition causes some skull bones to fuse prematurely and leads to abnormally large and separated thumbs and big toes.
  • Rubinstein-Taybi syndrome: This condition causes growth delays, abnormally large thumbs and big toes, intellectual disability, and feeding problems.
  • Russell-Silver syndrome (Russell-Silver dwarf): This condition causes restricted growth of the baby both before and after birth. A baby with this condition usually has a large head, prominent forehead, and triangular face.

Another potential cause of frontal bossing is congenital syphilis. If you are pregnant and have syphilis, you can pass on the infection to your baby, which can lead to several health problems. 

Taking trimethadione, an anti-seizure medicine, while you are pregnant may also lead to frontal bossing.

A condition that could lead to frontal bossing after birth is rickets. Rickets typically occurs in infants and young children and is caused by a lack of vitamin D. In addition to frontal bossing, rickets can lead to slow growth and soft skull bones.

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Diagnosing Frontal Bossing

If you see that your child’s forehead is larger than normal, you may want to make an appointment with your doctor to see if it is associated with another condition.

Diagnosis of frontal bossing is made based on physical examination and checking both your and your partner’s families’ medical history. Your doctor may ask about when you noticed the forehead’s abnormal appearance and if there are any other symptoms present.

To confirm a diagnosis of a specific condition, your doctor may also order some laboratory tests. Imaging tests like X-ray and MRI (magnetic resonance imaging) scans may be done to detect deformities and abnormal growths on the skull. Blood tests can be used to check for genetic conditions and hormone levels.

Treating Frontal Bossing

There is no way to treat frontal bossing on its own. However, the syndrome possibly linked to frontal bossing can be managed. Your doctor may recommend different ways to do so.

Cosmetic surgery may be used to manage frontal bossing. A small study looking at forehead reduction surgery found that there were some side effects, but that these side effects disappeared within a year. However, there are currently no specific guidelines for the surgical treatment of frontal bossing.

Preventing Frontal Bossing

There is no definitive way to prevent frontal bossing, but you can take some precautions before your baby is born.

One precaution is genetic counseling. During genetic counseling, a health care professional will help you assess the risk of your child being born with certain rare conditions.

You can then follow up with genetic testing. One type of genetic testing is carrier testing. A blood sample or cheek swab will be used to test if you or your partner are carriers for specific genetic conditions.

If you are identified as a carrier for a genetic disease, your doctor will discuss how you should proceed. Your doctor may also recommend some fertility medication.

Another form of genetic testing is prenatal testing. Prenatal testing is done using amniotic fluid and can test unborn babies for genetic conditions.

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Another precaution you can take is to get tested for syphilis while you are pregnant. If you test positive for syphilis, you can be treated with antibiotics to cure the infection. The sooner you get treatment, the less likely you will pass on the condition to your baby. 

If you take anti-seizure medication, make sure it is not trimethadione. If it is, ask your doctor about switching to another medication during your pregnancy. 

WebMD Medical Reference Reviewed by Dan Brennan, MD on March 11, 2021

Sources

SOURCES:

American Family Physician: “Basal Cell Nevus Syndrome: Guidelines for Early Detection.”

CDC: “Congenital Syphilis - CDC Fact Sheet”

CDC: “Genetic Counseling.”

GARD (Genetic and Rare Disease Information Center: “Hurler Syndrome.”

JOHNS HOPKINS MEDICINE: “Cleidocranial Dysplasia (CCD).”

Mayo Clinic: “Genetic Testing.”

Mount Sinai: “Frontal bossing.”

National Center for Biotechnology Information: “Frontal bossing.”

NORD (National Organization of Rare Disorders): “Crouzon Syndrome.”, “Pfeiffer Syndrome.”, “Rubinstein-Taybi Syndrome.”, “Russell-Silver Syndrome.”

Springer Nature Switzerland AG.: "Congenital Malformations and Syndromes: Early Diagnosis and Prognosis in Neonatal Medicine."

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