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Plastic Surgery - Congenital Lesions of the Skin and Soft Tissue (Birthmarks) 
 
 

Congenital Melanocytic Nevi

What are Congenital Melanocytic Nevi?
Treatment of Congenital Melanocytic Nevi

Sebaceous nevi

What are Sebaceous nevi?
Treatment of Sebaceous nevi

 

Congenital lesions of the skin and soft tissue represent a group of birthmarks that include congenital melanocytic (pigmented or colored) nevi, sebaceous nevi, and various other skin lesions.

Congenital Melanocytic Nevi

What are Congenital Melanocytic nevi?

Congenital melanocytic nevi (CMN) are the most common congenital skin lesions. They’re made up of abnormal collections of melanocytes (pigment producing cells) within the skin and soft tissue. They vary greatly in their appearance, and can appear within the first year of life as the cells begin to produce more pigment. Their color can vary from pale tan to a deep bluish black, which may be uniform or irregular, and are often thick in texture with hair which ranges from fine, light fuzz to coarse, thick follicles.

CMN can be classified based on their expected size at adulthood into small (<1.5cm), intermediate (1.5-19.9cm), and large (>20cm) lesions that are quite extensive and cover a massive area of the body. When large lesions are present, they may be accompanied by smaller satellite lesions of different sizes and numbers that can appear during the first 2-3 years of life.

Smaller CMN lesions are, by far, the most common occurring in 1 in 100 births. Intermediate lesions occur in 1 in 1,000 births, large lesions in 1 in 20,000 births and giant (>50cm) lesions in 1 in 500,000 births.

Although, the exact cause of these birthmarks is unknown, nevi form during development after a disruption in the migration and differentiation of neural crest cells into melanocytes. This causes immature cells to group abnormally along their course of migration instead of more evenly within the skin. Because of this, nevus cells often extend deep into the fat beneath the involved skin and require removal below the deepest level for more accurate results.

Treatment of Congenital Melanocytic Nevi

CMN lesions do carry a small but measurable risk of transformation into melanoma (skin cancer). Treatment of CMN must balance the potential risk of malignant change (developing into cancer) with cosmetic and functional concerns caused by both the lesion and its reconstruction. The risk for small or medium lesions is quite low, especially before puberty with less than 1 in 200,000 becoming cancerous. However, it may be recommended to remove them because of either the psychological effects caused by these birthmarks or if there is difficulty following them for significant changes (such as lesions of the back or scalp beneath the hair).

Removal can often be accomplished in the office under local anesthesia depending on the child’s age and the location of the lesion. Often, a multiple staged approach will be used to help minimize the length and width of the scar, which will be formed in the most favorable direction possible.

For more extensive nevi (large), the lifetime risk of melanoma increases to around 5-8% with a tendency for these cancers to arise earlier in childhood. Because of this and the potentially devastating appearance of these lesions, early removal is often encouraged.

Because the lesions must be removed with their underlying fat to improve removal of nevus cells, techniques that replace this full thickness of tissue are preferred. The method of tissue expansion involves a staged approach to removal and reconstruction of these larger lesions. This allows for the replacement tissue to have full thickness of normal tissue.

Tissue Expansion

A tissue expander is a silicone balloon attached to tubing with a remote port. It is placed under the skin while deflated and then gradually filled with saline over time, allowing the skin above it to stretch. This skin can then be used to cover a large area of removed nevus, and provides a good thickness and color match for reconstruction.

This reconstruction technique requires a minimum of two separate surgeries separated by about 10-14 weeks.  During the first surgery, an incision is made usually within the borders of the lesion and a pocket is created beneath the nearby normal skin and fat, but above the muscle layer.  A partially filled tissue expander is then placed in this pocket under the skin and its port is positioned in a nearby easily accessible area.

After a short healing period, we begin filling the expander in clinic.  After treating the skin over the port with a cream that numbs the area, small amounts of saline are injected each week through the port.  Over time, the expander gradually grows larger and stretches the normal skin. This actually causes the body to produce more skin similar to what happens during pregnancy. Once enough skin is generated, the expander is removed during a second surgery and the skin flaps are created from the expanded tissue. They are then rotated to cover the area of removed nevus.  This process can be repeated many times in many different areas to achieve removal of large areas of lesions with functional and aesthetic results.

In some cases, reconstruction will require a combination of tissue expansion and other techniques to achieve the most aesthetic result. For example, the ear and eyelid areas will often require skin grafting to recreate the thin tissues that are being removed. In other cases, where there is not enough local skin for adequate expansion, flaps of skin and soft tissue can be moved from another area of the body using a variety of techniques.

We work together with patients and their families, to evaluate each child’s specific birthmark and develop a customized, state-of-the-art treatment plan for removal and reconstruction.

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Sebaceous nevi

What are Sebaceous nevi?

Sebaceous (oil) nevi present at birth appear as waxy, hairless, yellow-orange plaques usually on the scalp, head, or neck. Sometimes, the lesions can form in lines called linear sebaceous nevus. Over time, these lesions can become nodular, or wart-like, and itchy, especially at puberty.

Sebaceous nevi are composed of cells that normally form oil glands; however, why they form is not fully understood. They carry a high risk (15 – 20%) of transforming into basal cell carcinoma, usually after puberty. Removal with reconstruction is strongly recommended.

Sebaceous nevus syndrome is the combination of large sebaceous nevi of the scalp and face associated with developmental delay, seizures, and eye and bony abnormalities.

Treatment of Sebaceous nevi

The treatment of sebaceous nevi is approached similar to congenital melanocytic nevi, using local removal, serial removal, or tissue expansion depending on the size and location of the lesions.

During removal, it is important to avoid excessive tension during closure as the surrounding skin tends to have more problems healing otherwise. Because of this, more stages or tissue expansion may be recommended to ensure healing and a better outcome for the final scar.

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