Nevus melanocytic congenital nevus giganteus - Altmeyers Encyclopedia

Synonym(s)

Giant congenital pigment nevus; giant congential melanocytic nevus; Giant Nevus; Giant pigment nevus congenital; nevus giganteus

Definition
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Congenital, hairy or hairless melanocytic nevus covering large body surfaces with a diameter > 20 cm. If the nevus is located in the buttocks or lumbar region it is called a bathing nevus. A giant pigment nevus can occur as a partial symptom of melanosis neurocutanea.

Occurrence/Epidemiology
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Frequency of occurrence: Approx. 1/20,000 newborns.

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Dermatology

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Complication(s)
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In about 5% of patients with melanocytic giant nevi, malignant degenerations are found either within the nevus or extracutaneously. > 50% of all observed malignant degenerations occur within the first 5 years of life. S.a. malignant melanoma in adolescents under melanoma, malign juveniles.

In a larger study (n=976 patients) of patients with congenital melanocytic giant nevi who developed invasive malignant melanoma, "thick" melanomas with lymph node and distant metastasis were observed more frequently. Patients should be observed at close intervals.

Therapy
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In the case of medium-sized melanocytic nevi, a multi-stage strip excision under general anesthesia is recommended depending on the location and extent.

In the case of large giant nevi that may cover several parts of the body, dermabrasion should be performed in the first few weeks of life. Even if melanocytes in the middle and deep dermis are not removed, the risk of melanoma can be significantly reduced by this surgical procedure.

Instead of dermabrasion, an ablative laser (e.g. Erbium-YAG laser) can also be used for this surgical procedure (only by appropriately experienced colleagues). The final results are obviously comparable.

If the procedures described are not possible, a clinical check-up every six months (photo documentation if necessary) and excision of suspicious areas.

Note(s)
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Extensive dermabrasion requires postoperative intensive management and can only be performed in dermatological centres with appropriate facilities.

Literature
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Bittencourt FV et al (2000) Large congenital melnocytic nevi ant the risk for development of malignant melanoma and neurocutaeous melanocytosis. Pediatrics 106: 736-741
De Raeve LE et al (2005) Distinct phenotypic changes between the superficial and deep component of giant congenital melanocytic naevi: a rationale for curettage. Br J Dermatol 154: 485-492
Chaplain EN (1974) The risk of malignancy in large congenital neavi. Plast Reconstr. Surgery 53: 421-428
Kopf AW et al (1979) Congenital nevocytic nevi and malignant melanomas. J Am Acad Dermatol 1: 123-130
Turkeltaub AE et al (2016) Characteristics, treatment, and survival of invasive malignant melanoma (MM) in giant pigmented nevi (GPN) in adults: 976 cases from the National Cancer Data Base (NCDB). J Am Acad Dermatol 74:1128-1134.