Congenital Nevi (Moles) in Children

Congenital melanocytic nevi, or congenital moles, are pigmented skin lesions that are present at birth or develop within a child’s first year. These brown spots are caused by an overgrowth of melanocytes, the cells responsible for skin pigment.

Congenital nevi in children are quite common, occurring in approximately one in 100 to one in 200 births. While most congenital nevi are benign (non-cancerous) and harmless, larger nevi can carry certain risks, including:

• Melanoma: Giant congenital nevi (bigger than 40 cm) have a higher risk of developing melanoma, a type of skin cancer.
• Psychosocial impact: Highly visible congenital nevi can lead to self-esteem issues, especially as children grow older.
• Skin health: Congenital nevi are susceptible to rashes. Scratching or irritating a mole can cause bleeding and lead to infection.
• Neurocutaneous melanocytosis: A rare condition linked to larger or more complex congenital nevi, which can affect the brain or central nervous system. This may occur without noticeable symptoms, but it can also lead to structural or functional changes that could impact your child’s health.

Congenital nevi can vary in size and shape-from small, flat spots to large, raised areas. Their colors can range from light brown to dark grey, and they typically grow proportionally with the child.

It’s important to look for changes such as:

• Darkening or bleeding
• Growth or enlargement out of proportion to your child’s growth
• Symptoms such itching, bleeding, or crusting

Congenital nevi are caused by an overgrowth of melanocytes. While the exact causes aren’t fully understood, they are believed to come from random genetic mutations that take place during fetal development. Nevi aren’t inherited, however some families have similar mole patterns.

At Boston Children’s Hospital, our Dermatology Program collaborates closely with the Department of Plastic and Oral Surgery to provide comprehensive care for congenital nevi in children. For patients with giant or high risk nevi, there may be involvement of the brain or spine, and patients may also be seen in the Department of Neurology.

Our expert team uses a variety of methods to diagnose these moles:

• Physical exam: Our experienced doctors assess the size, shape, color, and texture of your child’s mole to gather important information. A dermatoscope is a painless tool to enlarge and visualize the pigment within the nevus.
• Medical history: We will discuss any changes in the mole and ask about your family history of skin conditions.
• Imaging: For larger moles, we might use imaging tests to check how deep the mole goes under the skin and to see if it affects the brain, spine, or other organs.
• Biopsy: If there are any concerns about your child’s mole, we may perform a biopsy to take a small sample for further testing.

These comprehensive diagnostic steps allow our team to develop the best treatment options for your child.

At Boston Children’s, our approach to managing congenital nevi is tailored to each child’s unique needs, considering factors such as the mole’s size, location, and any noticeable changes.

Observation

We often recommend a watchful waiting approach for congenital nevi that show no signs of concerning change. We educate your child and your family on the natural changes that are expected as your child gets older, emphasizing the importance of regular check-ups to monitor any developments over time.

Surgical removal

We may recommend surgical removal if a mole is large, growing, or showing concerning changes. We may also consider surgery if the mole is in a highly visible area. The removal of large moles and those occurring in young children is typically performed under anesthesia in an outpatient or day-procedure setting. Smaller moles can often be removed in a doctor’s office with numbing medication, especially once a child gets older. The removed tissue is sent for testing by the pathologist to evaluate for malignancy.

For giant congenital nevi and for relatively large nevi in cosmetically sensitive areas, we may consider several surgical options to achieve the best aesthetic outcome. These include:

• Serial excision: Removing as much of the mole as possible, letting the scar heal and soften for several months, and then removing more of the mole until it is gone. This may take two to four stages.
• Tissue expansion: An expander is a balloon-like implant that can be placed under the normal skin near a mole that allows it to be stretched. After sufficient stretching, the mole and the expander are removed, and the stretched skin is used to repair the area where the mole was located.
• Skin grafting: Skin can be borrowed from elsewhere on a child’s own body.

Congenital nevi usually have a very favorable long-term outlook. However, regular check-ups and careful management are important.

At Boston Children’s, we offer comprehensive care for congenital nevi through a collaborative approach involving multiple specialties.

The Dermatology Program provides thorough evaluations and ongoing monitoring to assess your child’s mole and any potential changes. If surgery is needed, specialists from our Department of Plastic and Oral Surgery perform procedures focused on achieving both medical and cosmetic outcomes. Additionally, our Cancer and Blood Disorders Center offers expert consultation if there are concerns about the risk of melanoma or other skin cancers.

Based on the nevus and other risk factors, additional specialists such as neurologists, ophthalmologists, and endocrinologists may also be involved in your child’s care to create a personalized plan that prioritizes their health and well-being.