Congenital Nevus

Congenital Nevus

Congenital means to be present at birth. Nevus means mole which is usually dark in color either brown or black. The size of the nevus is either small (20 cm2). Sometimes hair can grow within the nevus. This hair is usually coarse and can become thick causing an unsightly appearance. Occasionally smaller nevi will surround giant nevi creating what is known as satellite nevi. If you have a congenital nevus that needs to be treated, our experienced plastic and craniofacial surgeon, Dr. Eric Payne, can help determine the best approach.

Classification

Small congenital nevi that are less than 1.5 cm2 tend to be irregularly shaped maculae or papules (skin lesions) with a tan to brown color. These will become darker as the child ages and goes through puberty. Medium congenital nevi are essentially the same as small nevi but the size range is from 1.5 – 20 cm2.

Giant congenital nevi are typically very dark in color with hair and a verrucous texture meaning it is raised dry scaly in appearance like a wart. The size is greater than 20 cm2 and covers a large area of the body. Other names are bathing suit nevi which cover the back, stomach, groin, and upper thighs like a bathing suit. Stocking nevi covers the entire leg or a large portion of the leg. Coat-sleeve nevi means to cover the arms entirely including the chest and back. Satellite nevi are usually present with giant congenital nevi. Giant congenital nevi are at risk of later developing into a malignant melanoma. Although this risk is small, the risk increases with the size of nevus.

Risk of Malignant Transformation

Typically the lifetime risk of malignancy in a small congenital nevus is less than 1%. The risk of a giant nevi developing into a melanoma is 5% to 10%. Small and medium-size nevi rarely develop into a malignant skin cancer before puberty. If giant congenital nevi develop into a melanoma, 50% of these will be between the ages of 3 and 5 years old.

Findings that raise suspicion of malignant changes are:

• Change of borders becoming more irregular
• Rapid increase in size
• Change in color and texture within the nevus
• Developing more satellite lesions around the giant congenital nevus

Management

There are several issues involved with congenital nevi. These involve the risk of malignant change, risk of scaring, unsightly appearance of the nevi, and psychological issues with other children or adults teasing the child about the nevus. For these reasons, giant congenital nevi are recommended to be removed as soon as possible.

Surgical technique options include skin flaps, skin grafts, and tissue expanders to cover the area left after the nevus has been removed. Often with small nevi the surgical excision is performed at one operation. With larger nevi, tissue expanders are often the best option in a child to minimize scaring. Tissue expansion involves surgically placing a balloon underneath the normal skin which is slowly inflated with saline or salt-water over six to eight weeks. During a second surgery the expander is removed along with the nevus. Then the excess skin created from the tissue expander is used to cover the area left from removal of the nevus. Sometimes the giant nevus is so large that multiple two-stage tissue expansion procedures are used to finally eliminate all of the nevus.

Definition of other Nevi:

• Café au lait spot – Meaning “coffee with milk” these macules or spots are hyperpigmentations that can be light brown to dark brown. Typically seen during infancy they become visible by 2 years old. These spots are frequently seen in large number with the diagnosis of neurofibromatosis. Cafe au lait spots are benign and do not require treatment.
• Blue nevus – Usually described as smooth dome shaped papules that are dark or bluish in color. Typically these lesions are benign but any change in shape or color should prompt a biopsy or removal of the lesion.
• Becker’s nevus – First noted by Samuel William Becker in 1948, this is a benign brown hyperpigmentation with hairy portions located mainly on the upper arm or back and chest. The borders of the nevus are irregular.
• Dysplastic nevus – A nevus with an atypical or abnormal melanocyte (pigment producing cell) that is irregular in shape and color. Some suggest that atypical moles or dysplastic nevus may become melanomas in the future. If there is any concern of change in shape or color, the mole or nevus should be removed.
• Halo nevus – A typically benign pigmented lesion with a circular white ring like a halo around the lesion. This is thought to be secondary to white blood cells causing an inflammation around the lesion. If the lesion is changing or suspicion of melanoma exists, then the lesion should be excised and sent as a biopsy to pathology.
• Mongolian spot – Typically seen in Asians and Native Americans, this lesion is like cafe au lait spots but bluish in color. Sometimes it is mistaken for a bruise.
• Nevus sebaceous – A lesion of dark tan color that is raised with a shiny coating located on the scalp or face. Typically seen at birth the lesion is frequently mistaken as a scar. Surgical excision is usually recommended since malignant transformation can occur at any age. The risk of cancer in nevus sebaceous is estimated between 5 – 10%.
• Spitz nevus – Often associated or confused with melanoma, this lesion is noted as a solitary round raised bump with red or dark pigmentation located on the face. Typically this lesion needs to be excised with uninvolved margins meaning the lesion is removed with a border of normal skin. This then is reconstructed by a plastic surgeon to close the wound with minimal deformity.

References

1. Marghoob AA. Congenital melanocytic nevi. Evaluation and management. Dermatol Clin 20:607-616, 2002.
2. Patterson WM, Lefkowitz A, Schwartz RA, et al. Melanoma in children. Cutis 65:269-272, 2000.
3. Rhodes AR, Silverman RA, Harrist TJ, et al. A histologic comparison of congenital and acquired nevomelanocytic nevi. Arch Dermatol 121:1266-1273, 1985.
4. Rhodes AR, Wood WC, Sober AJ, et al. Nonepidermal origin of malignant melanoma associated with a giant congenital nevocellular nevus. Plast Reconstr Surg 67:782-790, 1981.