On the development of neurocutaneous units--implications for the histogenesis of congenital, acquired, and dysplastic nevi.

This study of spontaneous abortions and fetal deaths in utero used immunostains to evaluate the structure of developing cutaneous nerves. Melan-A immunostains were also used to screen 25 cases of grossly normal fetal skin for occult fetal nevi. Discrete portions of epidermis were generally supplied by branches emanating from regularly spaced deep cutaneous nerves, producing a wedge shape, interpreted as neurocutaneous units (NCU). Deeper nerves embraced broader portions of epidermis. Some nerves ran parallel to epidermis, especially near the superficial vascular plexus at the junction of superficial and deep dermis. Nerve sheath stem cells in each NCU may supply the melanocytes needed by the corresponding portion of epidermis. Transformed nerve sheath stem cells may lead to formation of occult prenatal nevi, whose histology and histogenesis may best be understood in terms of NCUs. In particular, the size and shape of a nevus may be largely determined by its NCU of origin. Six fetal nevi were detected, and 3 occult lumbosacral Mongolian spots; all in deep dermis, no later than the middle of the second trimester, mainly with a pattern of singly dispersed deep dermal melanocytes. These findings suggest that congenital (prenatal) nevi begin as intradermal nevi. In addition to explaining congenital nevi, these findings have implications for the histogenesis of acquired (postnatal) nevi and dysplastic nevi.

[Pigment nevi in children]. / Pigmentnävi bei Kindern.

Almost all fair-skinned children demonstrate one or more pigment nevi at the integument. These usually develop in the first two decades of life as a result of an endogenous disposition and exogenous stimulants. While most pigmented nevi are per se harmless, congenital and atypical (dysplastic) nevi are considered as precursors of melanoma and risk indicators. Although one normal nevus in isolation generally presents no risk, children and adults with multiple pigment nevi are at increased risk of developing a melanoma in the course of their life. Since the onset of pigment nevi is undisputedly triggered by ultraviolet light, appropriate prevention and protection is crucial. The differential diagnosis between nevus cell nevi and melanoma is particularly challenging, especially in the case of atypical nevi.

Treatment of small congenital nevocellular naevi using a combination of ultrapulse carbon dioxide laser and Q-switched frequency-doubled Nd-YAG laser.

This report describes treatment combining Ultrapulse CO(2) laser and Q-switched frequency-doubled neodymium:yttrium-aluminum-garnet (Nd-YAG) laser for a number of congenital nevocellular naevi (CNN). The Ultrapulse CO(2) laser removes the superficial component, which contains most of the color, preserving the integrity of the reticular dermis. At a later stage, any residual color is targeted using the Nd-YAG laser. To date, a total of 10 histologically proven CNNs have been treated at the Laser Suite. The median age of the patients was 18 years (range, 13-24 years). All the patients were white females. The patients accepted for treatment had relatively small lesions (mean surface area, 352 mm(2); range, 50-1,092 mm(2)), but the lesions were either cosmetically sensitive or located in an anatomically critical area in which excision could result in a scar that would be unpredictable. The median follow-up period was 24 months. The overall results have been satisfactory, with reduction of color and no significant scarring. The minor textural and pigmentary changes were acceptable to the patients.

Malignant melanoma in a black child: predisposing precursors and management.

Malignant melanoma (MM) remains a pediatric rarity world-wide, but perhaps more so in black Africans. To the best of our knowledge, the current report of MM in a two-and-a-half-year-old Nigerian who had a pre-existing congenital giant hairy nevus is probably the first (in an accessible literature) in a black African child. Primary neoplastic transformation and metastatic spread were suggested by the appearance of multiple swellings over the "garment" precursor nevus at the posterior trunk, multiple ipsilateral axillary nodal enlargement, and fresh occipital swellings postadmission. Smaller-sized hyperpigmented lesions with irregular, nonlobulated, and frequently hairy surfaces were also discernible over the upper and lower extremities, but the face, anterior trunk, and mucosal surfaces were relatively spared. A diagnosis of MM was confirmed by the subsequent histopathologic findings from the fine-needle aspirate and biopsy specimens. Chemotherapy was initiated but was truncated shortly after by parent-pressured discharge. Despite the rarity of MM in a tropical African setting where management options are few, the current case underscores the need for a high clinical index of diagnostic suspicion, an early pursuit of investigative confirmation, and prophylactic excision in children with the predisposing skin lesions, like congenital giant hairy nevus. An expounded discourse of the possible precursors and management options of MM is provided. We emphasize the need for institutional cost subsidy for anticancer care in tropical children.

Origin of cutaneous melanoma in a congenital dysplastic nevus spilus.

Cutaneous melanoma developed in contiguity with a congenital nevus spilus on the leg of a 79-year-old white woman. The unique features of the nevus spilus in this case were its relatively large size (diameter, 8 cm), irregular gross appearance, lifelong stability until the recent appearance of a tumor nodule, and the presence of intraepidermal melanocytic dysplasia appearing as multifocal elements within darkly pigmented speckles distributed throughout a lightly pigmented background of lentigo simplex. Based on this observation, we suggest that the presence of intraepidermal melanocytic dysplasia in nevus spilus may be a predisposing factor for the development of melanoma. The malignant potential of "dysplastic" nevus spilus requires further study.