Topic
Melanocytic nevus
About: Melanocytic nevus is a research topic. Over the lifetime, 1418 publications have been published within this topic receiving 44870 citations. The topic is also known as: mole & Melanotic nevus.
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TL;DR: Evidence is presented suggesting that superficial spreading melanoma and lentigo maligna melanoma (Hutchinson9s melanotic freckle) show a long period of superficial growth, followed by the relatively rapid appearance of nodules or deeper invasion within the primary lesion.
Abstract: Summary This paper describes the histogenesis of 3 forms of human malignant melanoma: superficial spreading melanoma, nodular melanoma, and lentigo maligna melanoma. A comparative analysis by computer of the biologic behavior and clinical characteristics of the different neoplasms has been done. An additional 60 tumors have been studied by serial block sectioning. Evidence is presented suggesting that superficial spreading melanoma and lentigo maligna melanoma (Hutchinson9s melanotic freckle), though evolving at different rates, show a long period of superficial growth, followed by the relatively rapid appearance of nodules or deeper invasion within the primary lesion. This change in the nature of the primary lesion may be due to the appearance of one or more strains of cells of aggressive biologic potential. Thus the primary melanoma may exist for a relatively long period of time during which host selectional forces act to permit the growth of quite malignant strains of cells. It is these cells that seem to be capable of deeper growth. The subdivision of each of the forms of melanoma into 5 anatomic levels of invasion permits the accurate assignment of prognosis to each case. It is suggested that melanomas are tumors of the epidermal melanocytes and are not necessarily derived from melanocytic nevi. Each melanoma has a distinctive clinical appearance, even in its superficial and curable phases, and this appearance is the same whether or not the process arose in association with a melanocytic nevus.
2,058 citations
TL;DR: In this article, the authors evaluated the timing of mutations in BRAF during melanocytic neoplasia and found that mutations resulted in the V599E amino acid substitution in 41 of 60 (68%) melanoma metastases, 4 of 5 (80%) primary melanomas and, unexpectedly, in 63 of 77 (82%) nevi.
Abstract: To evaluate the timing of mutations in BRAF (v-raf murine sarcoma viral oncogene homolog B1) during melanocytic neoplasia, we carried out mutation analysis on microdissected melanoma and nevi samples. We observed mutations resulting in the V599E amino-acid substitution in 41 of 60 (68%) melanoma metastases, 4 of 5 (80%) primary melanomas and, unexpectedly, in 63 of 77 (82%) nevi. These data suggest that mutational activation of the RAS/RAF/MAPK pathway in nevi is a critical step in the initiation of melanocytic neoplasia but alone is insufficient for melanoma tumorigenesis.
1,611 citations
TL;DR: Six evident lesional steps of tumor progression form the neoplastic system that affects the human epidermal melanocyte: 1) the common acquired melanocytic nevus; 2) a melanocytes with lentiginous melanocytics hyperplasia; 3) a metastatic melanoma with aberrant differentiation and melanocytical nuclear atypia; 4) the radial growth phase of primary melanoma; 5) the vertical growth phase: a growth form characteristic of metastases.
909 citations
TL;DR: The uneven distribution of BRAF mutations strongly suggests distinct genetic pathways leading to melanoma, and the high mutation frequency in melanomas arising on intermittently sun-exposed skin suggests a complex causative role of such exposure that mandates further evaluation.
Abstract: The RAS/mitogen-activated protein kinase pathway sends external growth-promoting signals to the nucleus. BRAF, a critical serine/threonine kinase in this pathway, is frequently activated by somatic mutation in melanoma. Using a cohort of 115 patients with primary invasive melanomas, we show that BRAF mutations are statistically significantly more common in melanomas occurring on skin subject to intermittent sun exposure than elsewhere (23 of 43 patients; P<.001, two-sided Fisher's exact test). By contrast, BRAF mutations in melanomas on chronically sun-damaged skin (1 of 12 patients) and melanomas on skin relatively or completely unexposed to sun, such as palms, soles, subungual sites (6 of 39 patients), and mucosal membranes (2 of 21 patients) are rare. We found no association of mutation status with clinical outcome or with the presence of an associated melanocytic nevus. The mutated BRAF allele was frequently found at an elevated copy number, implicating BRAF as one of the factors driving selection for the frequent copy number increases of chromosome 7q in melanoma. In summary, the uneven distribution of BRAF mutations strongly suggests distinct genetic pathways leading to melanoma. The high mutation frequency in melanomas arising on intermittently sun-exposed skin suggests a complex causative role of such exposure that mandates further evaluation.
630 citations
TL;DR: If confirmed in larger studies, the results presented on number of nevi and melanoma risk suggest a readily identifiable melanoma-prone group that could be followed to detect early malignant melanoma.
Abstract: A study of 121 melanoma patients and 139 control subjects from the University of California, San Francisco clinics was conducted among whites to examine the relationship between number of melanocytic nevi and cutaneous melanoma. Nevi that measured 2 mm or more in diameter were counted over the body by a dermatologist and a dermatology fellow. The average number of nondysplastic melanocytic nevi that were 2 mm or greater in diameter was 97 for melanoma patients and 36 for control subjects (p
457 citations