Abstract:O nevo melanocitico congênito está presente em aproximadamente 1% dos recém nascidos. As lesões classificadas como pequenas e medias são relativamente comuns, ao passo que o nevo gigante, maior que 20 cm no maior diâmetro, é uma condição mais rara cuja a incidência esta estimada em 1 para cada 20 mil nascimentos. As lesões melanociticas congênitas pequenas e médias têm um risco de degeneração maligna baixo, raramente ocorrendo na infância. Por outro lado, estima-se um risco entre 5 a 12 % de um melanoma se des… Show more
“…Malignant melanoma is a rare tumor during childhood and accounts for up to 0.9% of all pediatric malignancies [1, 2]. A congenital melanocytic nevus (CMN) is clinically defined as a melanocytic lesion that is present at birth or develops during infancy from preexistent melanocytes [3–5]. CMNs typically affect the trunk and proximal parts of the limbs, scalp, and neck, but might involve any other skin surface.…”
Background
A giant congenital melanocytic nevus (GCMN) is found in 0.1% of live-born infants. If present, the lesion has a chance of about 6% to develop into malignant melanoma. Both children and adults can be affected by malignant melanoma arising in a giant congenital nevus. Up to 95% of GCMNs harbor
NRAS
mutations, and mutations in the
BRAF
,
MC1R
,
TP53
, and
GNAQ
genes have also been described. The individualization of therapy is required, but diagnostic and prognostic criteria remain controversial.
Case presentations
We report two cases: 1) melanoma arising in a giant congenital nevus during the first month of life complicated with neurocutaneous melanosis (NCM), and 2) melanoma arising in a giant congenital nevus during the first 6 months of life. Pathology, immunohistochemistry, and genetic analyses of tumor tissue were performed. The first case revealed only a non-pathogenic P72R polymorphism of the
TP53
gene in the homozygote condition. For the second case, a Q61K mutation was detected in the
NRAS
gene.
Conclusion
Malignant melanoma associated with GCMN is rare and therefore poorly understood. Outcomes have been linked to the stage at diagnosis, but no additional pathological prognostic factors have been identified. The most frequent genetic event in giant CMNs is NRAS mutations, which was discovered in one of our cases. To accumulate evidence to improve disease prognosis and outcomes, children with congenital melanocytic nevus should be included in a systemic follow-up study from birth.
“…Malignant melanoma is a rare tumor during childhood and accounts for up to 0.9% of all pediatric malignancies [1, 2]. A congenital melanocytic nevus (CMN) is clinically defined as a melanocytic lesion that is present at birth or develops during infancy from preexistent melanocytes [3–5]. CMNs typically affect the trunk and proximal parts of the limbs, scalp, and neck, but might involve any other skin surface.…”
Background
A giant congenital melanocytic nevus (GCMN) is found in 0.1% of live-born infants. If present, the lesion has a chance of about 6% to develop into malignant melanoma. Both children and adults can be affected by malignant melanoma arising in a giant congenital nevus. Up to 95% of GCMNs harbor
NRAS
mutations, and mutations in the
BRAF
,
MC1R
,
TP53
, and
GNAQ
genes have also been described. The individualization of therapy is required, but diagnostic and prognostic criteria remain controversial.
Case presentations
We report two cases: 1) melanoma arising in a giant congenital nevus during the first month of life complicated with neurocutaneous melanosis (NCM), and 2) melanoma arising in a giant congenital nevus during the first 6 months of life. Pathology, immunohistochemistry, and genetic analyses of tumor tissue were performed. The first case revealed only a non-pathogenic P72R polymorphism of the
TP53
gene in the homozygote condition. For the second case, a Q61K mutation was detected in the
NRAS
gene.
Conclusion
Malignant melanoma associated with GCMN is rare and therefore poorly understood. Outcomes have been linked to the stage at diagnosis, but no additional pathological prognostic factors have been identified. The most frequent genetic event in giant CMNs is NRAS mutations, which was discovered in one of our cases. To accumulate evidence to improve disease prognosis and outcomes, children with congenital melanocytic nevus should be included in a systemic follow-up study from birth.
“…1-3 Histologically, it is characterized
by the presence of melanocytes between collagen bundles at the reticular dermis and
around adnexal structures.…”
Melanomas can arise either de novo (70%) or from pre-existing
melanocytic lesions (30%). Of the latter, most cases arise at the dermoepidermal
junction from small congenital or acquired non-blue nevi while only a few arise
from blue nevi, notably the cellular subtype and less commonly the common
(dendritic) type. Melanomas that arise from blue nevi usually occur on the scalp
with greater frequency, as in the case described. Although previous studies have
discussed melanoma arising from giant congenital blue nevi, few have discussed
those arising from intermediate blue nevi. We present a case of a 52-yearold man
with melanoma on the scalp evolving from an intermediate congenital common blue
nevus.
“…Sendo estabelecido que: pequeno (< 1,5 cm de diâmetro), médio (1,5 cm -20 cm no maior diâmetro) e gigante (> 20 cm de diâmetro). Podem ainda ser lisos ou elevados, com coloração variando entre o castanho claro e o escuro, uniformes e com bordas definidas, com ou sem pelos (os com pelos são denominados nevos pilosos gigantes) 2 .…”
Section: Introductionunclassified
“…As lesões classificadas como pequenas e médias são relativamente comuns, representam cerca de 1% dos nascimentos 1 , ao passo que o nevo gigante é uma condição rara, cuja incidência está estimada em 1 para cada 20 mil nascimentos. Está é a classificação adotada neste trabalho, por ser utilizada em trabalhos que estudam o risco de surgimento de melanoma 2,3 .…”
Carneiro Junior LVF et al. Tratamento cirúrgico do nevo melanocítico gigante Surgical treatment of giant melanocytic nevi RESUMO O nevo melanocítico congênito está presente em aproximadamente 1% dos recém nascidos. As lesões classificadas como pequenas e médias são relativamente comuns, e possuem risco de degeneração maligna baixo. Por outro lado, as lesões chamadas de gigantes são raras e possuem maior risco de malignização. Neste trabalho é relatada a experiência do autor, no tratamento cirúrgico dos nevos melanocíticos gigantes. Descritores: Nevo. Melanoma. Dispositivos para Expansão de Tecidos.
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