Genetic and Epidemiologic Evaluation of Dysplastic Nevi

Dysplastic Nevus Syndrome (DNS) has been defined as that trait characterized by the presence of at least one dysplastic melanocytic nevus. DNS was originally described in kindreds having multiple members with melanoma. Various types DNS have been described in other situations to include individuals with apparently sporadic cases, familial DNS without melanoma and individuals with apparently sporadic DNS with melanoma. These categories are based on historical information in general, and not on examination of family members. In all cases, the presence of dysplastic nevi appear to confer some increased risk of melanoma, which varies between the groups. Similarly cutaneous melanoma is thought to occur in several distinct populations-random individuals without DNS, individuals with sporadic DNS, and those with familial DNS. Genetic analysis of DNS has been largely confined to the classically ascertained kindreds associated with melanoma. These studies have usually used diagnostic criteria based on pathology of clinically selected material, and that evidence suggests that DNS is inherited as an autosomal dominant trait in these families. Surveys of the general population have detected rates of dysplastic nevi of 5% 20%. In our Utah-based studies, we have evaluated probands and family members from three groups. These included kindreds with multiple occurrences of melanoma, random individuals with at least one dysplastic nevus, and cases of melanoma with unknown family history. Controls were spouses of study subjects. We sought to determine the percentage of each group associated with dysplastic nevi and/or genetic DNS. The range of phenotype of patients with dysplastic nevi was large with some individuals having few nevi, none of which were clinically atypical, and others having greater than 100 nevi. The prevalence of dysplastic nevi in at least one of two biopsies in Utah population controls is presently Wtimated at 62%. Some probands with melanoma as well as some of their relatives had elevated numbers of nevi, suggesting that this predisposition to melanoma may be inherited.     

The dysplastic nevus: recognition and management

The recognition of atypical or dysplastic nevomelanocytic nevi potentially provides clinicians with another means of identifying individuals at increased risk for cutaneous malignant melanoma. However, a great deal of controversy still surrounds these lesions, their significance, and the clinical and histologic criteria needed for their diagnosis at present. In general, dysplastic nevi tend to be asymmetrical and larger (greater than 5 mm) than ordinary acquired nevi, have a macular component, irregular and ill-defined borders, and haphazard (variegate) coloration. A clinical diagnosis of dysplastic nevi must be confirmed by histopathology, since not all clinically atypical nevi are dysplastic. While precise histopathologic criteria for dysplastic nevi are lacking, most authorities agree that an abnormal nevomelanocytic proliferative pattern as manifested by increased numbers of basilar melanocytes and/or abnormal junctional nevomelanocytic nesting in the setting of lentiginous epidermal hyperplasia, variable degrees of nevomelanocytic nuclear atypia, and a lymphocytic host response are consistent with a histologic diagnosis of dysplastic nevi. Current data for individuals with dysplastic nevi and a family history of cutaneous malignant melanoma (at least two family members with cutaneous malignant melanoma) indicate a relative risk for cutaneous malignant melanoma about 148 times that of the general population. In comparison, cutaneous malignant melanoma risk seems lower for individuals with familial dysplastic nevi (but without familial cutaneous malignant melanoma) and "sporadic" dysplastic nevi. With respect to progression to melanoma, probably the vast majority of dysplastic nevi remain stable or possibly regress. Management of individuals with histologically confirmed dysplastic nevi involves periodic skin examinations. Regional overview and life-size photography are helpful in following these patients. Patients should also be instructed in the examination of their own skin. While a definite relationship between sun exposure and dysplastic nevi remains unproved, the use of sunscreens and avoidance of unnecessary sun exposure are advised. Examination of family members for atypical melanocytic lesions is also recommended.     

On the Interplay of Telomeres,Nevi and the Risk of Melanoma

The relationship between telomeres, nevi and melanoma is complex. Shorter telomeres have been found to be associated with many cancers and with number of nevi, a known risk factor for melanoma. However, shorter telomeres have also been found to decrease melanoma risk. We performed a systematic analysis of telomere-related genes and tagSNPs within these genes, in relation to the risk of melanoma, dysplastic nevi, and nevus count combining data from four studies conducted in Italy. In addition, we examined whether telomere length measured in peripheral blood leukocytes is related to the risk of melanoma, dysplastic nevi, number of nevi, or telomere-related SNPs. A total of 796 cases and 770 controls were genotyped for 517 SNPs in 39 telomere-related genes genotyped with a custom-made array. Replication of the top SNPs was conducted in two American populations consisting of 488 subjects from 53 melanoma-prone families and 1,086 cases and 1,024 controls from a case-control study. We estimated odds ratios for associations with SNPs and combined SNP P-values to compute gene region-specific, functional group-specific, and overall P-value using an adaptive rank-truncated product algorithm. In the Mediterranean population, we found suggestive evidence that RECQL4, a gene involved in genome stability, RTEL1, a gene regulating telomere elongation, and TERF2, a gene implicated in the protection of telomeres, were associated with melanoma, the presence of dysplastic nevi and number of nevi, respectively. However, these associations were not found in the American samples, suggesting variable melanoma susceptibility for these genes across populations or chance findings in our discovery sample. Larger studies across different populations are necessary to clarify these associations.     

Molecular pathogenesis of malignant melanoma: a different perspective from the studies of melanocytic nevus and acral melanoma

The Clark model for melanoma progression emphasizes a series of histopathological changes beginning from benign melanocytic nevus to melanoma via dysplastic nevus. Several models of the genetic basis of melanoma development and progression are based on this Clark’s multi-step model, and predict that the acquisition of a BRAF mutation can be a founder event in melanocytic neoplasia. However, our recent investigations have challenged this view, showing the polyclonality of BRAF mutations in melanocytic nevi. Furthermore, it is suggested that many melanomas, including acral and mucosal melanomas, arise de novo, not from melanocytic nevus. While mutations of the BRAF gene are frequent in melanomas on non-chronic sun damaged skin which are prevalent in Caucasians, acral and mucosal melanomas harbor mutations of the KIT gene as well as the amplifications of cyclin D1 or cyclin-dependent kinase 4 gene. Amplifications of the cyclin D1 gene are detected in normal-looking ‘field melanocytes’, which represent a latent progression phase of acral melanoma that precedes the stage of atypical melanocyte proliferation in the epidermis. Based on these observations, we propose an alternative genetic progression model for melanoma.     

Real-time expression of hTERT in primary melanoma biopsies

Skin melanoma is by far the most lethal skin cancer, it is unpredictable by nature and presents a severe diagnostic problem. One of the major issues in melanoma diagnostics is to differentiate it with confidence from a dysplastic nevus. Thus, the aim of this study was to evaluate hTERT expression on a spectrum of dermal lesions (from normal skin toprimary melanoma) in order to examine its possible role as a diagnostic marker in melanoma diagnostics. In this study we analyzed the expression of hTERT by real-time PCR on 58 freshly obtained biopsy samples (4 samples of normal skin, 12 dermal nevi, 23 dysplastic nevi, 19 primary melanomas). Our results showed slightly greater hTERT expression in dysplastic nevi than melanomas with major data overlap. Considering the given results, hTERT does not seem to be a reliable diagnostic marker for melanoma.     

Acquired melanocytic nevi as risk factor for melanoma development. A comprehensive review of epidemiological data

Acquired melanocytic nevi (MN) in Caucasian populations are important markers for the risk of melanoma development. The total number of MN on the whole body is the most important independent risk factor for melanoma and the risk of melanoma development increases almost linearly with rising numbers of MN. Additionally, the presence of atypical MN and of actinic lentigines are likewise independent risk factors for melanoma. Atypical mole syndrome should be defined by the presence of many acquired MN and a threshold number of atypical MN. Acquired MN develops mainly during childhood and adolescence in the first two decades of life. The number of acquired nevi seems to be related to hereditary factors and nevus-prone families exist. The amount of sun exposure is the most important environmental risk factor for nevus development, particularly in early childhood. Interestingly, sunburns may play a role in nevus development, but seem not to be required, and even moderate sun exposure promotes the process. Therefore, preventive measures for nevus and melanoma development should target young children and adolescents.     

Expression of cyclins A and E in melanocytic skin lesions and its correlation with some clinicopathologic features

Cyclins play a fundamental role in the cell cycle. Recent studies have focused on their role in the development of various malignancies. The objective of this study was to evaluate and compare the expression of cyclins A and E in common nevi, dysplastic nevi and malignant melanomas, and to investigate the relationship between cyclin expression and some pathological parameters such as tumor thickness, ulceration, regression, and mitotic rate, as well as several clinical and phenotypic parameters such as skin phototype, hair and eye color, number of nevi, personal or family melanoma history, and personal history of nonmelanoma skin cancer (NMSC). A total of 102 melanocytic skin lesions, including 30 common nevi, 38 dysplastic nevi and 34 melanomas, were examined. Expression of cyclins was detected by immunohistochemistry and quantified as a percentage of immunostained cell nuclei in each sample. Significant differences in expression of both cyclins were found between all lesion types: the median percentage of cyclin A-positive nuclei was 8.2% in melanomas, 3.4% in dysplastic nevi, and 0.95% in common nevi (p < 0.001). The corresponding percentages for cyclin E were 9.5%, 4.25% and 1.44% (p < 0.001). Expression of both cyclins was significantly higher among patients with a personal history of NMSC. Cyclin A was also significantly overexpressed in patients with a high total nevus count (TNC) compared to moderate and low TNC. Expression of cyclins did not significantly correlate with the other clinicopathologic features investigated. These findings indicate the possible involvement of cyclins A and E in the pathogenesis of malignant melanoma. Our results also show a potential diagnostic significance of these cyclins as markers allowing discrimination between dysplastic nevi and melanoma.     

Ten-year study on the correlation of clinical and pathohistological diagnosis of dysplastic nevi

The aim of the study was to analyze the clinical prevalence and pathohistological correlation of dysplastic nevi. In the period between 2000 and 2009, in the Outpatient Clinic of Referral Centre for Melanoma of the Ministry of Health and Social Welfare of the Republic of Croatia, 12,344 patients were examined, and 35.07% of them were surgically removed in the same institution. Among the patients, 69.16% had clinically diagnosed melanocytic tumor. Out of them, 28.39% were dysplastic. Dysplastic nevus was pathohistologically diagnosed in 20.02% of pathohistologically diagnosed melanocytic tumors. There was women predominace among patients with clinically diagnosed dysplastic nevi (65.22%). The most frequent localization was the trunk in both sexes, women 78.18%, men 76.75%. The coincidence of clinical and pathohistological diagnosis of dysplastic nevus was 30.70%. The results of this study, based on a large number of patients could be a significant contribution in understanding characteristics of dysplastic nevus, its clinical and pathohistological complexity. We hope that the data will contribute to the creation of general accepted protocols in the diagnostics of dysplastic nevus.     

The usefulness of c-Kit in the immunohistochemical assessment of melanocytic lesions

C-Kit (CD117), the receptor for the stem cell factor, a growth factor for melanocyte migration and proliferation, has shown differential immunostaining in various benign and malignant melanocytic lesions. The purpose of this study is to compare c-Kit immunostaining in benign nevi and in primary and metastatic malignant melanomas, to determine whether c-Kit can aid in the differential diagnosis of these lesions. c-Kit immunostaining was performed in 60 cases of pigmented lesions, including 39 benign nevi (5 blue nevi, 5 intradermal nevi, 3 junctional nevi, 15 cases of primary compound nevus, 11 cases of Spitz nevus), 18 cases of primary malignant melanoma and 3 cases of metastatic melanoma. The vast majority of nevi and melanomas examined in this study were positive for c-Kit, with minimal differences between benign and malignant lesions. C-Kit cytoplasmatic immunoreactivity in the intraepidermal proliferating nevus cells, was detected in benign pigmented lesions as well as in malignant melanoma, increasing with the age of patients (P=0.007) in both groups. The patient's age at presentation appeared to be the variable able to cluster benign and malignant pigmented lesions. The percentage of c-Kit positive intraepidermal nevus cells was better associated with age despite other variables (P=0.014). The intensity and percentage of c-Kit positivity in the proliferating nevus cells in the dermis was significantly increased in malignant melanocytic lesions (P=0.015 and P=0.008) compared to benign lesions (compound melanocytic nevi, Spitz nevi, intradermal nevi, blue nevi). Immunostaning for c-Kit in metastatic melanomas was negative. Interestingly in two cases of melanoma occurring on a pre-existent nevus, the melanoma tumor cells showed strong cytoplasmatic and membranous positivity for c-kit, in contrast with the absence of any immunoreactivity in pre-existent intradermal nevus cells. C-Kit does not appear to be a strong immunohistochemical marker for distinguishing melanoma from melanocytic nevi, if we consider c-Kit expression in intraepidermal proliferating cells. The c-Kit expression in proliferating melanocytes in the dermis could help in the differential diagnosis between a superficial spreading melanoma (with dermis invasion) and a compound nevus or an intradermal nevus. Finally, c-Kit could be a good diagnostic tool for distinguishing benign compound nevi from malignant melanocytic lesions with dermis invasion and to differentiate metastatic melanoma from primary melanoma.     

"Halo nevi" and UV radiation

Halo nevi, also termed Sutton nevi, are defined as benign melanocytic nevi that are surrounded by an area of depigmentation resembling a halo. Halo nevi are common in children and young adults, with a mean age at onset of 15 years. The incidence in the population is estimated to be approximately 1%. Affected individuals frequently have multiple lesions which are usually localized on the back. A familial tendency for halo nevi has been reported. The etiology of halo nevi is unknown. It is an autoimmune response and T lymphocytes are considered to play a key role in the progressive destruction of nevus cells. Halo nevi may be associated with autoimmune disorders such as vitiligo, Hashimoto thyroiditis, alopecia areata, celiac disease, atopic dermatitis and others. It has been proved that halo nevi are detected after an intense sun exposure especially after sunburns. The etiology of halo nevi, association with malignant melanoma and the role of sun exposure in the development of halo nevi are discussed.     

Poster Abstracts

One of the major roles of the Nemours Biomolecular Core is to provide one-on-one mentoring for clinicians engaging for the first time in molecular genetics projects. This core function has successfully grown to include unique inter-institutional research collaborations. In this poster, we will present the detailed molecular analysis that was performed in collaboration with clinicians in DE and PA, on a rare and fascinating case of agminated Spitz nevus, and the methodologies developed for this project. Differentiating a Spitz nevus from a Spitzoid melanoma is often a challenging task faced by dermatopathologists. While the dysplastic nevus theory supports the notion that a Spitz nevus can progress to a melanoma, there is molecular evidence that refutes this possibility. Namely, Spitz nevi can carry unique mutations found in the mitogen-activated protein kinase (MAPK) pathway that are not found in melanomas. We used DNA sequencing as well as STR analysis for genotyping and copy number evaluation. The analysis revealed two HRAS “gain of function mutations” resulting in A11S and G13R amino acid substitutions in the ras protein and hyper activation of the MAPK signaling pathway. Allelic specific amplification PCR assays were developed to elucidate the allelic provenance of each mutation. We discovered that the maternally inherited allele carried both mutations in cis. The HRAS mutations observed in the patient’s Spitz nevi, HRAS copy number increase, as well as allelic imbalance at 11p with gain of the maternal allele, was also observed in tissue containing the mutated gene.     

Black lesions of the skin

Benign melanocytic lesions include lentigo, ephelid (freckle), pigmented nevus, sacral spot, blue nevus, and combined nevus and blue nevus. Malignant melanocytic lesions are melanomas, which arise from melanocytes at the epidermodermal junction, or, rarely, from blue nevi. They usually originate in brown plaques known as lentigo maligna, in pigmented nevi, or in normal skin. Melanoma is diagnosed clinically in less than 50 per cent of instances. Biopsy is therefore of great importance, since practically all melanoma can be cured by adequate early resection.     

NRAS and BRAF Mutations in Melanoma-Associated Nevi and Uninvolved Nevi

According to the prevailing multistep model of melanoma development, oncogenic BRAF or NRAS mutations are crucial initial events in melanoma development. It is not known whether melanocytic nevi that are found in association with a melanoma are more likely to carry BRAF or NRAS mutations than uninvolved nevi. By laser microdissection we were able to selectively dissect and genotype cells either from the nevus or from the melanoma part of 46 melanomas that developed in association with a nevus. In 25 cases we also genotyped a control nevus of the same patients. Available tissue was also immunostained using the BRAF^V600E-mutation specific antibody VE1. The BRAF^V600E mutation was found in 63.0% of melanomas, 65.2% of associated nevi and 50.0% of control nevi. No significant differences in the distribution of BRAF or NRAS mutations could be found between melanoma and associated nevi or between melanoma associated nevi and control nevi. In concordant cases immunohistochemistry showed a higher expression (intensity of immunohistochemistry) of the mutated BRAF^V600E-protein in melanomas compared to their associated nevi. In this series the presence of a BRAF- or NRAS mutation in a nevus was not associated with the risk of malignant transformation. Our findings do not support the current traditional model of stepwise tumor progression.     

Macroscopic spectral imaging and gene expression analysis of the early stages of melanoma

BACKGROUND: The stages of melanocytic progression are defined as atypical (dysplastic) nevus, melanoma in situ, melanoma in the radial growth phase (RGP), melanoma in the vertical growth phase (VGP), and melanoma in the metastatic growth phase (MGP). Melanoma in situ and RGP melanoma often develop in contiguous association with atypical nevi. This frequently poses a problem with respect to their early detection. Furthermore, unlike cells obtained from VGP and MGP melanomas, cells derived from melanoma in situ and RGP melanoma do not proliferate in vitro. Thus, compared to the late stages of the disease, less information is available regarding genes expressed in the early stages. MATERIALS AND METHODS: To determine whether spectral imaging, a recently developed optical imaging technique, can detect melanoma in situ and RGP melanoma arising in melanoma precursor lesions, atypical nevi in patients with a clinical history of melanoma were subjected to noninvasive macroscopic spectral imaging. To determine at what stage in the progression pathway of melanoma genes having important biological functions in VGP and MGP melanomas are activated and expressed, lesions of melanoma in situ were analyzed by immunohistochemistry and in situ hybridization for expression of some of these known molecular and immunologic markers. RESULTS: The present study demonstrates the capability of noninvasive spectral imaging to detect melanoma in situ and RGP melanoma that arise in contiguous association with atypical nevi. Furthermore, the study provides evidence that genes and antigens expressed in VGP and MGP melanoma are also expressed in melanoma in situ. CONCLUSIONS: Because of the dark and variegated pigmentation of atypical nevi, melanoma in situ and RGP melanoma that arise in these melanoma precursor lesions are often difficult to recognize and thus frequently go unnoticed. The application of new optical screening techniques for early detection of melanoma and the identification of genes expressed in the early stages of melanoma development are two important avenues in the pursuit of melanoma prevention. The investigations presented here document that macroscopic spectral imaging has the potential to detect melanoma in its early stage of development and that genes essential for the proliferation and cell adhesion of VGP and MGP melanoma are already expressed in melanoma in situ.     

Comparison of image analysis with flow cytometry for DNA content analysis in pigmented lesions of the skin.

The DNA ploidy of 85 melanocytic skin lesions was determined by flow cytometry (FCM) and interactive image analysis (IA) using nuclear extracts of paraffin-embedded tissue. Of the 85 lesions analyzed, 43 were malignant melanomas in different stages of evolution, 15 were dysplastic nevi, 11 were Spitz nevi, and 16 were other types of nevi. Some of the last had features of congenital nevi. Within the melanoma category, there was 42% aneuploidy by FCM versus 56% by IA. Of those melanomas aneuploid by FCM, all but one were aneuploid by IA. All dysplastic nevi, 10/11 Spitz nevi and 15/16 other nevi were diploid by both methods. One of the 16 nevi from the "other types" category was tetraploid by IA but diploid by FCM. A single Spitz nevus was tetraploid by FCM but diploid by image analysis. While our results suggest that interactive IA is potentially a more sensitive method than FCM for detecting aneuploidy in cutaneous pigmented lesions, it remains to be shown whether this will translate into better prognostic assessment of the biologic behavior of melanocytic neoplasms than provided by flow cytometric ploidy analysis.     

Dermatoscopy and High Frequency Sonography: Two Useful Non-Invasive Methods to Increase Preoperative Diagnostic Accuracy in Pigmented Skin Lesions

Dermatoscopy and high frequency sonography have recently been combined to increase diagnostic preoperative accuracy in the treatment of pigmented skin lesions. In this monocentric study 80 patients with pigmented skin lesions were evaluated clinically, by dermatoscopy, and 20 MHz-sonography followed by dermatohistopathological evaluation; 39 malignant melanomas, 37 common nevi, 3 dysplastic nevi, and 1 nevus Spitz were diagnosed histologically. In 72 of the 80 cases (91.3%) dermatoscopical diagnoses were confirmed by histopathology, compared to only 79% correct clinical diagnoses. For the mere clinical diagnosis of melanoma sensitivity was 79%, specificity was 78% and diagnostic accuracy was 65%. All diagnostic values increased by dermatoscopy: sensitivity reached 90%, specificity was 93%, and diagnostic accuracy was 83%. In order to determine tumor thickness preoperatively tumor thickness was measured by 20 MHz sonography. The correlation of tumor thickness between histometric and sonographic results was determined for nevi (r = 0.93) and melanoma (r = 0.95); 74.3% of melanomas were diagnosed correctly within an 0.2 mm range. Regarding the clinical important limit of 1 mm tumor thickness, 87.2% were diagnosed in accordance with histometric evaluation. An increase of 18% in diagnostic accuracy by dermatoscopy and 87.2% of correctly diagnosed cases of tumor thickness of malignant melanoma by high frequency sonography clearly demonstrate that these methods should be considered standard procedures in the diagnosis of pigmented skin lesions and will facilitate the decision on necessary surgical treatment.     

Dysplastic Nevus Syndrome in The Netherlands

In Europe, the occurrence of familial melanoma in combination with the occurrence of dysplastic nevi in melanoma patients has been reported by groups from Scotland, France, Italy, and The Netherlands. The major publications of these groups are briefly mentioned and summarized. This report specifically describes nine extensive Dutch pedigrees. Clinical an genetic studies were performed in kindreds among whom three or more individuals with melanoma occurred in at least two consecutive generations. Three hundred sixty-two living persons older than 10 years were screened. The mean number of family members was 60, which makes these pedigrees preeminently suited for genetic studies. Spouses were not included in the study. One hundred eighty individuals were recognized as gene carriers. After correction for bias of ascertainment, we calculated a segregation rate of 0.45, compatible with dominant inheritance. Of the 180 living or alive at the start of the study, 40 had a melanoma, 118 had dysplastic nevi, and 22 were regarded as obligate gene carriers on the basis of their position in the pedigree. The finding of nonpenetrance and reduced penetrance of the characteristic phenotype of the dysplastic nevus syndrome has important consequences for daily practice. When a family is requested to attend the pigmented lesion clinic, all members have an a priori risk of 50% of carrying the gene. Individuals without any abnormalities form the majority, and cases of nonpenetrance and low penetrance are mixed in with the seemingly normal cases. The consequence for our research group was to follow all family members until it is possible to distinguish definitely gene carriers from normal family members. Other malignancies occurred at an increased rate among these families. In two families, the occurrence of several kinds of cancer was obvious. Twenty-four instances of nonmelanoma cancer were found, among which were seven cases of pancreatic carcinoma     

Recombinant gamma-interferon induces changes in expression and shedding of antigens associated with normal human melanocytes, nevus cells, and primary and metastatic melanoma cells

Recombinant gamma-interferon (rIFN-gamma) induced or augmented the expression of HLA-DR class II antigens on melanocytes isolated from newborn foreskin, from congenital, common acquired, and dysplastic nevi, and from primary and metastatic melanoma. The stimulatory effect of rIFN-gamma on HLA-DR antigen expression was suppressed by the addition of the phorbol ester TPA or its analog PDBu to the culture medium. Whereas rIFN-gamma did not significantly alter the expression of melanoma-associated, non-class II antigens on melanoma cells, there was a marked decrease in the expression of antigens associated with nevus cells. In addition, rIFN-gamma stimulated shedding of antigens. Increased antigen shedding was most apparent for an intracytoplasmic melanoma-associated protein of 80kd, followed by the ganglioside GD2 and by an alkali labile ganglioside. The simultaneous stimulation of class II antigen expression and shedding of melanoma-associated antigens as well as suppression of nevus-associated antigen expression could play an important role in the host immune response to premalignant and malignant melanocytic lesions.     

Evaluation of human monoclonal antibody (2-139-1) in cutaneous melanocytic neoplasms in fixed tissue sections.

Despite the growing list of xenogeneic monoclonal antibodies (MAb) that recognize malignant melanoma-associated antigens (MAA) in formalin-fixed, paraffin-embedded tissue, none has been able to detect epitopes found in malignant melanomas and not in melanocytic nevi. A human MAb, 2-139-1, that showed promise in this regard was evaluated against 85 melanocytic neoplasms, including malignant melanoma and histological simulators, particularly Spitz's nevus. MAb 2-139-1 stained 18 (53%) of 34 melanomas, eight (57%) of 14 dysplastic nevi, six (38%) of 16 Spitz's nevi, and three (14%) of 21 banal nevi, which included three small congenital nevi. We observed a significant increasing trend in reactivity (% positive cells x intensity) associated with the potential for malignancy (p for linear trend = 0.002). We conclude that human MAb 2-139-1 is applicable to the study of melanocytic neoplasms in routinely processed tissue. Although the ability of this MAb to separate benign from malignant cells is not absolute, our results suggest that the expression of the 2-139-1 epitope may be an early event in melanocytic tumor progression.     

Novel Multiple Markers to Distinguish Melanoma from Dysplastic Nevi

Background

Distinguishing melanoma from dysplastic nevi can be challenging.

Objective

To assess which putative molecular biomarkers can be optimally combined to aid in the clinical diagnosis of melanoma from dysplastic nevi.

Methods

Immunohistochemical expressions of 12 promising biomarkers (pAkt, Bim, BRG1, BRMS1, CTHRC1, Cul1, ING4, MCL1, NQO1, SKP2, SNF5 and SOX4) were studied in 122 melanomas and 33 dysplastic nevi on tissue microarrays. The expression difference between melanoma and dysplastic nevi was performed by univariate and multiple logistic regression analysis, diagnostic accuracy of single marker and optimal combinations were performed by receiver operating characteristic (ROC) curve and artificial neural network (ANN) analysis. Classification and regression tree (CART) was used to examine markers simultaneous optimizing the accuracy of melanoma. Ten-fold cross-validation was analyzed for estimating generalization error for classification.

Results

Four (Bim, BRG1, Cul1 and ING4) of 12 markers were significantly differentially expressed in melanoma compared with dysplastic nevi by both univariate and multiple logistic regression analysis (p < 0.01). These four combined markers achieved 94.3% sensitivity, 81.8% specificity and attained 84.3% area under the ROC curve (AUC) and the ANN classified accuracy with training of 83.2% and testing of 81.2% for distinguishing melanoma from dysplastic nevi. The classification trees identified ING4, Cul1 and BRG1 were the most important classification parameters in ranking top-performing biomarkers with cross-validation error of 0.03.

Conclusions

The multiple biomarkers ING4, Cul1, BRG1 and Bim described here can aid in the discrimination of melanoma from dysplastic nevi and provide a new insight to help clinicians recognize melanoma.