Approximately 1% to 2% of newborns have congenital melanocytic nevi. Smaller lesions (as opposed to giant pigmented nevi) are brown patches or plaques, often with an oval or lancet configuration. Lesions may resemble café au lait macules initially, but darker pigmentation, variegated speckles, textural changes, and elevation develop with time and help to differentiate these lesions (Fig. 193-3). Thick, dark, coarse hair frequently is associated with congenital melanocytic nevi (Fig. 193-4). These lesions vary in site and size but are most often solitary. Congenital melanocytic nevi pose a very slightly increased risk for the development of malignant melanoma, usually developing during adulthood. Surgical removal may be considered to improve the cosmetic appearance of the patient or to reduce the likelihood of malignant transformation, although some patients and physicians elect for observation. Excisional biopsy is indicated when malignant change is suspected.
Giant congenital melanocytic nevi are defined as nevi that would be approximately 20 cm in length in adulthood; in a neonate, this translates to 9 cm on the head and neck and 6 cm on the rest of the body. These lesions appear as color variegated, light brown to black patch or plaques, sometimes with smaller macules and papules (satellite nevi) in addition. The affected skin may be smooth, nodular, or leathery. Prominent, dark hypertrichosis is often present. Neuromelanosis, the presence of melanocytes in the central nervous system, may be associated with giant congenital melanocytic nevi. Affected patients may be asymptomatic or have hydrocephalus and seizures; in symptomatic patients, death often results during early childhood. Malignant melanoma develops in approximately 2% to 10% of patients with giant congenital melanocytic nevi, in either the cutaneous lesion or the neural melanocytes. In contrast to small and medium congenital melanocytic nevi, melanoma is more likely to develop during childhood. Because of the incidence of malignant degeneration and extensive deformity, surgical excision should be considered for resectable lesions. The use of tissue expansion techniques has greatly improved the capability for surgical removal of large lesions.
Figure 193-3 Congenital melanocytic nevus (buttock).
Figure 193-4 Hairy congenital nevus.
Acquired melanocytic nevi are common skin lesions. Melanocytic nevi may occur at any age; however, the lesions developmost rapidly in prepubertal children and teenagers. Melanocytic nevi are well-delineated, round to oval, brown maculesand papules. Lesions are most common on the face, upper torso,and arms. Family history, fair skin, and sun exposure are considered major risk factors. Irregular pigmentation, rapid growth,bleeding, and a change in configuration or borders suggest signsof malignant degeneration and biopsy should be performed.Malignant melanoma is rare in childhood; however, there isan alarming increase in incidence in adolescence, especially inthose who use indoor tanning. Education of parents and children regarding the risks of sun exposure, appropriate sun protection, and recognition of worrisome lesions is important.
Vascular anomalies can be divided into two major categories:tumors and malformations. Vascular tumors are characterized by hypercellularity, proliferation, and growth. Vascular malformations, however, are developmental defects derived from the capillary, venous, arterial, or lymphatic vessels. In contrast tohemangiomas, vascular malformations remain relatively staticover time. Differentiating between these entities is importantbecause they have different prognoses and clinical implications.
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