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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The frequencies of chromatid breaks and gaps in metaphase cells fixed 2 h after G2 phase X-irradiation (1 Gy) were in almost all cases at least two- to three-fold higher in skin fibroblasts from individuals with genetic conditions predisposing to cancer than in comparable cells from clinically normal controls. Previously, we reported this response in all cancer-prone genetic disorders tested including ataxia telangiectasia, Bloom's syndrome, Fanconi's anemia, xeroderma pigmentosum (XP), familial polyposis, Gardner's syndrome, hereditary malignant melanoma, dysplastic nevus syndrome and cancer family members. One exception was XP-A. In this report we add information on skin fibroblasts from retinoblastoma, Wilms' tumor and XP-C patients, 13 clinically normal controls and six cell lines from fetal or infant cells. Factors affecting the response are identified and include pH, temperature, cell density, culture medium or serum, microbial contamination and visible light exposure (effective wavelength 405 nm). Because of experimental variability, known normal controls should be used in each group of assays. With adequate control of the above factors this response could provide the basis of a test for detecting individuals carrying genes that predispose to a high risk of cancer.
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PMID:Factors affecting and significance of G2 chromatin radiosensitivity in predisposition to cancer. 256 34

Eighty-eight melanocytic lesions on the soles of Japanese were histologically investigated. Increased numbers of solitary melanocytes above the basal layer of the epidermis were often found in the benign melanocytic nevi on the sole: in 5 lesions of 9 congenital melanocytic nevi, 22 of 65 acquired melanocytic nevi, and 1 of 5 dysplastic nevi. In addition, a moderate degree of nuclear atypia of proliferating melanocytes was frequently observed in the benign melanocytic nevi on the sole: in 3 lesions of 9 congenital melanocytic nevi, 17 of 65 acquired melanocytic nevi, and 2 of 5 dysplastic nevi. Therefore it cannot be said that increased numbers of solitary atypical melanocytes above the basal layer is a characteristic histologic feature of early malignant melanoma in situ. Combining the intraepidermal distribution patterns of melanocytes and maximum diameter of the lesion, we propose criteria for histopathologic diagnosis of plantar malignant melanoma in situ.
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PMID:[Intraepidermal distribution patterns of melanocytes in the melanocytic lesions on the sole: proposed criteria for histopathologic diagnosis of plantar malignant melanoma in situ]. 258 70

Dysplastic nevi were diagnosed according to the ABCDE rule for recognition of early melanomas in 11 patients with familial dysplastic nevus syndrome (DNS) and in 39 patients with the sporadic variant of DNS. All these 50 patients exhibited multiple dysplastic nevi. On routine histological examination melanocytic atypia confirming the histological diagnosis of dysplastic nevus was found only in 12/50 cases. However, when cut consecutively dysplastic nevi with melanocytic atypia were diagnosed in 17 further cases (34%). In most cases (72.4%) only a mild degree of atypia (grade I) was found. Dysplastic nevi with severe melanocytic atypia (grades II-III) were found in all groups of sporadic and familial variants of DNS (with and without melanoma). To improve the prognostic value of the histological examination in dysplastic nevi significantly it must be of interest to add the degree of melanocytic atypia. With increasing degree of melanocytic atypia also the typical histological feature of dysplastic nevi become more significant. Since such atypia in dysplastic nevi is not necessarily sited in the centre of the lesion and since in most cases melanocytic atypia occurs focally, we believe that histological examination of dysplastic nevi must be undertaken by step section. Lesions suspected of being dysplastic nevi must be excised with margins of at least 2-5 mm for a correct histological diagnosis.
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PMID:[Focal melanocytic atypia in dysplastic nevus cell nevi. Results of a serial section study]. 260 69

The propagation of pigmented cells derived from normal skin, common and precursor nevi, and primary and metastatic melanoma in tissue culture has allowed the study of tumor progression under experimental conditions. In accordance with Clark's hypothesis, which is based on histopathological observations, cells isolated from different stages of tumor progression show a stepwise development of a malignant phenotype as defined by different biological parameters: life span in culture, anchorage-independent growth, increased growth autonomy from exogenous growth factors, expression of melanoma-associated antigens, progressively severe chromosomal abnormalities, and tumorigenicity in nude mice. Qualitative and quantitative differences exist between normal melanocytes and nevus cells on the one hand, and between VGP primary and metastatic melanoma cells on the other. Little information, however, is available on cells from dysplastic nevi and RGP primary melanoma cells. Preliminary results suggest that the biologic, immunologic and genetic characterization of these cells from the intermediate stages of tumor development will significantly increase our understanding of the pathogenesis of melanoma.
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PMID:Tumor progression in melanoma: the biology of epidermal melanocytes in vitro. 264 21

Two hypotheses have been presented. The first states that melanomas commonly evolve from normal melanocytes by a tumor progression pathway from a banal nevus to a nevus with dysplasia, to a micro-invasive, and then to a fully evolved, tumorigenic, primary melanoma which has competence for metastasis. It is important to note that not all melanomas follow this complete pathway. As Foulds noted long ago, tumors may bypass any of the stages of tumor progression. Thus, many melanomas do not, apparently, arise in nevi, and melanomas may evolve "fully formed" as pure tumorigenic nodules. However, from the biological point of view, study of the benign potential precursors (nevi and, especially, dysplastic nevi as well as microinvasive melanomas) may well reveal mechanisms of progression that are applicable to all melanomas, and perhaps to other solid tumors as well. From a clinical viewpoint, follow-up and education of patients at increased risk for melanoma, and early diagnosis of melanomas in their curable, microinvasive stages may result in a reduction of mortality from the disease, even without influencing its overall incidence. The melanomas that occur on plantar and palmar (acral) skin appear to progress through a microinvasive stage similar to that of other cutaneous melanomas. However, the significance of precursor and marker lesions (if any exist) in acral melanoma remains to be elucidated by clinicopathologic and epidemiologic studies. The possibility of etiologic agents other than UV light, such as chemical carcinogens and/or viruses, should be investigated in these cases. The second hypothesis presented here, that UV light is etiologic for the common cutaneous melanoma of white populations, has support from clinical, epidemiologic, and biologic observations. From a biologic viewpoint, ultraviolet light has all of the properties that might enable it to act as a complete carcinogen, and to enhance tumor progression in melanocytic "potential-precursor" lesions. Clinically, it seems appropriate to encourage patients (and members of the general population, as well) to adopt sensible attitudes to sun exposure. By such means, it is possible that some melanomas might be prevented, or that the rate and incidence of progression to more-advanced stages might be inhibited.
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PMID:Human melanocytic neoplasms and their etiologic relationship with sunlight. 265 3

The common acquired conjunctival nevus usually undergoes progressive maturation and only exceptionally gives rise to conjunctival melanoma. Pure junctional nevi are rare except in childhood. Histologically, however, a junctional nevus may be indistinguishable from primary acquired melanosis (PAM) with atypia, a condition of middle-aged and elderly individuals that has a tendency to evolve into melanoma. Nevi in adolescents may attract a vigorous lymphocytic response and may cause clinical and histologic confusion with other entities, particularly a regressing nodule of melanoma that occurs predominantly in adults. Rarely, congenital conjunctival nevi are identified, sometimes in patients with adjacent congenital nevi of the eyelid. A variety of unusual nevi, including balloon-cell nevi, Spitz nevi, epithelioid cell nevi, dysplastic nevi, recurrent nevi, episcleral melanosis and the nevus of Ota, blue and cellular blue nevi, melanocytoma, and composite or mixed nevi all may be identified in the conjunctiva. Concepts of histogenesis as well as the clinical, light microscopic, and ultrastructural features of these and other benign pigmentary conditions of the conjunctiva are described.
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PMID:Benign conjunctival melanocytic lesions. Clinicopathologic features. 265 39

The incidence of cutaneous malignant melanoma (CMM) is increasing at an alarming rate. Risk factors that may contribute to the increase include ultraviolet (UV) radiation, lack of skin pigmentation, and genetic, hormonal, and immunologic factors. Although the exact nature of the relationship between melanoma and UV radiation is unclear, evidence suggests a correlation between sun exposure and CMM incidence. Caucasians with fair skin who sunburn and freckle easily and individuals with numerous nevi or moles and/or atypical nevi or moles are also at increased risk of CMM. Melanoma almost always is curable by surgery if it is detected early. Nursing can make a major contribution to reducing the morbidity and mortality of CMM both through educating the public in prevention and early detection measures and by screening individuals for suspicious lesions.
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PMID:Cutaneous malignant melanoma: nursing's role in prevention and early detection. 266 Jan 18

This study examined noncultured and cultured melanomas and related precursor specimens for (i) mutated ras genes using polymerase chain reaction (PCR) methodology, (ii) correlation of mutated ras genes with differentiation related phenotypic characteristics, (iii) expression of ras-encoded p21 proteins in tissues by immunoperoxidase analysis, (iv) quantitative expression of mutated and wild-type ras encoded p21 proteins by flow cytometry, and (v) correlation between p21 expression, the occurrence of ras mutations, and cell cycle kinetics. The results of these studies are (1) 24% of cultured malignant melanomas have activated ras genes, with N-ras being activated ten times as frequently as Harvey (Ha)-ras. Each example of an activated ras gene showed a mutation at the 61st codon of the protein, with the exception of one melanoma which showed a mutation at codon 13 of the N-ras gene; (2) all the melanomas displaying an activated ras gene had a similar cell surface phenotype and appear to come from a similar phase of differentiation; (3) 5-6% of noncultured primary and metastatic melanomas have mutated ras genes; (4) no ras gene mutations were found in any precursor lesion, specifically normal nevi and dysplastic nevi; (5) immunoperoxidase analysis of paraffin-embedded specimens indicated no quantitative or qualitative alterations in p21 expression that correlate with tumor progression; (6) there were no observable differences in p21 expression between melanoma cells growing exponentially or in plateau phase, or between melanoma cells with or without ras mutations; nor were any cell kinetic differences found between cells with and without mutated ras genes. These studies suggest that the role of ras mutations may be limited to an indirect involvement in the transformation of a subset of melanomas.
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PMID:Analysis of ras oncogenes in malignant melanoma and precursor lesions: correlation of point mutations with differentiation phenotype. 268 63

We have used polymerase chain reaction (PCR), an amplification procedure, and oligonucleotide hybridization to detect ras gene point mutations in DNA from melanoma tumor samples. Genomic DNA was examined from 40 specimens of melanotic lesions, including benign nevi, primary melanomas, lymph node metastases, and systemic metastases. Adjacent normal skin or peripheral blood was analyzed as control material in 28 cases. ras mutations were detected overall in 25% of malignant tumors. In addition, mutations of all three ras genes were detected. We observed ras mutations in 2 of 4 benign atypical nevi (2 X K12), 4 of 22 primary melanomas (3 X K12, 1 X H12, 1 X N61), and 4 of 14 secondary (5 X K12, 1 X N61) tumors. One with a primary melanoma had concurrent K12 and H12, and two patients with secondary tumors had concurrent K12/N61 and K12 Asp/K12 Val mutations, respectively, making a total of 10 of 40 (25%) patients with ras mutations. This is the first demonstration of K-ras mutations in human melanoma. The presence of K-ras mutations in nevi, putative melanoma precursors, suggests that ras activation may be an early event in melanoma development. No correlation between tumor thickness and the presence of a ras mutation was observed.
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PMID:ras mutations in human melanotic lesions: K-ras activation is a frequent and early event in melanoma development. 269 57

The incidence and mortality of malignant melanoma (MM) has markedly increased in the Federal Republic of Germany. The data available show a doubling of incidence in the past 15 years and a doubling of mortality in the past 30 years. Germany holds a middle range in the incidence list of MM compared to worldwide data: 6-8 MM were registered per 100,000 inhabitants and year in Germany during the mid eighties, whereas 5 x higher incidences where reported from Australia and the southern states of the USA; incidences higher than 6-8/100,000 where found in the Scandinavian countries. While sun exposure is regarded as the most important risk factor in the international epidemiology of MM, a relationship between sun exposure and increasing risk of MM could not be clearly established for the German population. In contrast, the total number of melanocytic nevi (MCN) and the occurrence of dysplastic nevi where found to be significant markers of an increased relative risk for developing MM in the German population. The increase of the relative risk was 16 x for persons with greater than 60 MCN compared to individuals with greater than or equal to 10 MCN and there was an additional 7 x increase of the relative risk for persons with greater than or equal to 1 dysplastic nevus. The course of the disease is lethal in most cases of metastatic malignant melanoma. 90% of all patients in the Federal Republic of Germany, however, were first diagnosed in clinical stage I (= primary tumor alone) and the average 10 years survival rate was 70% in the time period since 1970. Multivariate regression analysis revealed that the most important prognostic factors in stage I MM were tumor thickness and sex. This finding should be taken into consideration for a prognostic classification of stage I MM.
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PMID:[Epidemiology of malignant melanoma in West Germany in an international comparison]. 269 8


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