Proto-oncogene c-kit expression in malignant melanoma: protein loss with tumor progression

The c-kit gene encodes a transmembrane receptor that has tyrosine kinase activity. c-kit plays a role in hematopoiesis, gametogenesis, and melanogenesis. c-kit is found in melanocytes, and there is evidence that expression is lost in melanoma. We studied 85 melanocytic lesions for c-kit by immunohistochemical techniques using a monoclonal antibody. The lesions included banal nevi, junctional and compound nevi with melanocytic dysplasia, nontumorigenic radial growth phase melanoma, tumorigenic vertical growth phase melanoma, and metastatic melanoma. We found intense membrane staining in normal melanocytes and mast cells. Staining in compound nevi was strongest in junctional and superficial dermal components, whereas dermal nevi showed weak reactivity. Dysplastic nevi stained strongly, particularly in junctional cells. In melanoma, strong reactivity was most prominent in radial growth phase disease, but there was little or no staining in vertical growth phase and metastatic melanomas. In summary, c-kit protein is expressed in normal melanocytes, benign nevi, dysplastic nevi and nontumorigenic melanoma, but expression is lost in tumorigenic primary melanomas and metastases. The role of c-kit loss in advanced melanoma requires additional investigation.     

Variants of melanoma

The current classification of malignant melanomas gives recognition to superficial spreading melanoma, lentigo maligna melanoma, acral lentiginous melanoma, and nodular types. In addition, neurotropic and desmoplastic types are recognized. The relativity inherent in the diagnosis of melanoma, provides the basis for the classification of melanomas on the basis of size. Lesions measuring 1 mm or less in vertical dimensions are unlikely to metastasize; they qualify as borderline melanocytic neoplasia of indeterminant malignant potential. The current classification has little relevancy to the category of variant nevi with the exceptions of malignant cellular blue nevus and melanoma arising in giant congenital nevi. A classification of variant melanomas as related to variant nevi is proposed. From a different perspective, a classification of melanomas with attention to nesting and cytological patterns in vertical growth is proposed: this alternate approach gives recognition to lesions that might otherwise be classified as "nevoid" melanomas. It also provides a default category for lesions that might otherwise be assigned to the Spitz nevus-like category. All of these tools for the manipulation of the real and virtual images of melanomas have been emphasized in the concept of minimal deviation melanoma.     

Heterogeneous expression of immunotherapy candidate proteins gp100, MART-1, and tyrosinase in human melanoma cell lines and in human melanocytic lesions

In recent years, it has become evident that T cells can recognize peptides of melanocytic lineage antigens such as gp100, MART-1, and tyrosinase at the tumor cell surface and can subsequently destroy these cells. It is thus feasible to develop immunotherapeutic approaches based on the melanocytic marker profiles of melanoma cells. One of the predictors of the success rate of such a treatment is the extent of positive (target) tumor cells within the lesions of the patient. First, we investigated the presence of these three proteins in 18 human melanoma cell lines using RT-PCR and immunohistochemistry. In 11 cell lines, mRNA and protein of all three markers could be detected; in one cell line, only two markers were present, and six melanoma cell lines showed no evidence for these markers. Secondly, we stained frozen sections of 105 human melanocytic lesions, 13 common nevocellular nevi, 13 atypical nevi, 13 early primary melanomas (Breslow < 1.5 mm), 25 advanced primary melanomas (aPM; Breslow > or =1.5 mm), and 41 melanoma metastases (MM) with antibodies against glycoprotein 100, melanoma antigen recognized by T cells, and tyrosinase. In addition, we used the 3,4-dihydroxy-L-phenylalanine reaction to detect tyrosinase enzyme activity as a confirmation of the tyrosinase immunohistochemical results in a subset of the lesions. In the benign lesions, glycoprotein 100 was more prominently expressed in epidermal melanocytes, whereas melanoma antigen recognized by T cells was encountered in all or nearly all dermal melanocytes in all nevocellular nevi and atypical nevus lesions. Tyrosinase was found in a lower percentage of melanocytes, both in the epidermis and in the dermis within these lesions. With regard to heterogeneity of staining within the malignant lesions, we found that 54% (early primary melanomas), 48% (aPMs), and 56% (MM) of the lesions stained within the same staining category for all three proteins studied. Approximately 17% of the aPM and MM lesions did not show positive tumor cells for any of the three proteins. We conclude that a subgroup of patients with high expression should be selected for immunotherapeutic treatment approaches based on the presence of these proteins.     

Associated factors in the prevalence of more than 50 common melanocytic nevi, atypical melanocytic nevi, and actinic lentigines: multicenter case-control study of the Central Malignant Melanoma Registry of the German Dermatological Society

Several case-control studies identified common and atypical melanocytic nevi as major risk indicators for the development of cutaneous melanoma. The present investigation was planned to detect factors associated with the prevalence of these melanoma risk markers. Whole-body examination findings and interview data of 513 melanoma patients and 498 age- and sex-matched control subjects were analyzed. Existence of more than 50 common melanocytic nevi and the presence of atypical melanocytic nevi were significantly related to age and gender, with significantly elevated relative risk for their prevalence before the age of 60 and in males. Additionally, sunburns before the age of 20 were significantly associated with both more than 50 common melanocytic nevi (relative risk = 1.7) and the presence of atypical melanocytic nevi (relative risk = 1.5). Actinic lentigines were found more frequently with increasing age, and the presence of actinic lentigines was significantly related to a tendency of freckling in adolescence (relative risk = 2.0) and to two or more sunburns after the age of 20 (relative risk = 1.6). In conclusion, sunburns before the age of 20 contribute to the development of multiple melanocytic nevi and atypical melanocytic nevi. In adulthood, this type of sun exposure is associated with the development of actinic lentigines. The relative risk of developing cutaneous melanoma increases in association with the development of these benign melanocytic lesions.     

Quantification of vascularity in nodular melanoma and Spitz's nevus

Spitz's nevi are acquired benign melanocytic skin tumors. Usually they are differentiated from nodular melanoma by clinical and histopathological criteria. Since Spitz's nevi are one of the most common simulators of nodular melanomas their bizarre histopathology may cause diagnostic confusion and make it difficult to differentiate these two melanocytic tumors. One of the histologic features shared by Spitz's nevus and nodular melanoma is prominent vascularity. The ability of malignant melanoma to induce angiogenesis is well established whereas benign melanocytic tumors do not have a prominent overall vascularity. The purpose of this study was to find out whether the degree of vascularity of nodular melanomas differs significantly from that of benign Spitz's nevi. In this study the number of microvessels and the vessel area were determined in 23 Spitz's nevi and 16 nodular melanomas. The number of microvessels and the vessel area were determined on Ulex Europaeus agglutinin I-stained sections by computer-assisted image analysis. Two methods of measurement were used, namely systematic and selective sampling. Measurement of the whole tumor specimen (systematic sampling) revealed a vessel count of 10.83/field (SD +/-5.97) for Spitz's nevi whereas nodular melanomas exhibited a significantly lower (p=0.04) vessel count of 6.44/field (SD +/-3.85). This difference was even more pronounced when the vessel area (Spitz's nevi: 17.85x10-4mm2, SD +/-10.32; nodular melanomas: 7.88x10-4mm2, SD +/-5.23) was investigated (p < 0.001). The difference in vessel area and vessel count was insignificant for areas exhibiting the greatest vascularity (selective sampling). Measurement of vessel count and vessel area lead us to conclude that Spitz's nevi have a significantly higher vascularity than do nodular melanomas. Our results thus indicate that angiogenesis in these pigmented lesions is not correlated with malignancy.     

Malignant melanoma from the dermatologic perspective

Early recognition and treatment of thin cutaneous melanomas (stages Ia and Ib) have contributed to a decreased case-fatality rate during the past several decades. The only known preventable risk factor for melanoma is sun protection in childhood, which directly affects the number of melanocytic nevi developing in an adult. Additional risk factors, clinical features, and the malignant potential of precursor lesions are discussed. The four major clinicopathologic subtypes of melanoma are described with recommendations for appropriate biopsy techniques for suspected melanoma. Nationwide skin cancer screenings by dermatologists and greater public awareness of the warning signs of melanoma have enhanced detection of early melanoma and have promoted chances for a cure.     

The ABCD rule in dermatoscopy: analysis of 500 melanocytic lesions

500 melanocytic lesions were examined by dermatoscopy using the ABCD rule prior to excision and histologic diagnosis. Regular nevi (n = 272) exhibited a score of 3.55 +/- 0.87, nevi with histologic signs of dysplasia (n = 190) a score of 4.0 +/- 0.68 and melanomas (n = 30) a score of 5.08 +/- 1.24. This study suggests that the ABCD rule of dermatoscopy greatly facilitates the evaluation of melanocytic lesions. When the dermatoscopic score is higher than 4.2, melanoma should be considered.     

Prognostic significance of allelic losses in primary melanoma

Loss of genetic material, including loss of loci on chromosome arms 6q, 9p, and 10q, occurs frequently in cutaneous melanoma but infrequently in benign melanocytic nevi or other melanocytic lesions, suggesting that these genetic alterations are important in the development and progression of melanoma. To examine whether allelic loss is of prognostic importance in melanoma, disease-free survival was related to loss of heterozygosity on 6q, 9p and 10q in 83 individuals with sporadic primary cutaneous melanoma. Loss of chromosome arms 6q and 10q were each significantly associated with a poorer clinical outcome (P=0.013 and P=0.001 respectively). In a subgroup of 41 subjects whose primary tumours were allelotyped, the fractional allelic loss (FAL) at 39 autosomal arms also significantly correlated with disease-free survival (P=0.013), with an increase in FAL associated with a poorer outcome; this association remained significant when controlled for tumour thickness (P=0.035). In addition, a greater proportion of cells were immunopositive for Ki67 antigen, p53 and p21WAF1 protein in the primary melanomas than in the benign melanocytic nevi, however, only p53 over-expression was significantly associated with improved survival (P=0.041).     

Effect of Pichia anomala killer toxin on Candida albicans

BACKGROUND: An acral lentiginous melanoma in situ on the sole is often difficult to differentiate with the naked eye from an acquired plantar melanocytic nevus. Recent technical advances in epiluminescence microscopy have contributed to the differentiation of these two pigmented skin lesions. OBJECTIVE: In this study, the correlation between dermatoscopic and histopathologic findings of acral lentiginous melanoma in situ on the sole are compared to those of acquired plantar melanocytic nevi. METHODS: Three acral lentiginous melanomas in situ on the sole, and two cases of acral lentiginous melanoma were compared with 50 acquired plantar melanocytic nevi by means of dermatoscopy and histopathology. Results: The dermatoscopic surface profiles of acquired melanocytic nevi were composed of linear pigmentation accentuated mainly on the sulcus superficialis. Histologically, some areas of the sulcus superficialis corresponded to rete ridges of the epidermis, and nests of nevus cells were also often located there. In contrast, the acral lentiginous melanomas in situ showed diffuse, irregularly shaped pigmentation distributed in a disorderly fashion over the entire surface. Histologically, isolated areas of proliferation and small nest formations of atypical melanocytes were irregularly distributed in the epidermis. CONCLUSION: A distinctive dermatoscopic feature of acral lentiginous melanoma in situ is diffuse and irregular pigmentation over the entire surface of the lesion. This feature is helpful for differentiating acral lentiginous melanoma in situ from acquired plantar melanocytic nevi.     

Survival and histopathologic characteristics of human melanocytic nevi transplanted to athymic (nude) mice

Melanocytic nevi (n = 406) covering a range of sizes and gross morphologic features were excised from human donors, sampled for histologic diagnosis, and transplanted to athymic (nude) mice. Ninety percent of these xenografts survived transplantation, of which a subset was irradiated daily with ultraviolet light to promote neoplastic transformation. Over 16 weeks of observation, nearly all grafts histologically showed focal inflammatory cell infiltration and fibrosis, progressing in approximately 30% of grafts to complete regression at final observation. During the inflammatory phase, the nevi often had junctional intraepidermal melanocytic hyperplasia in a lentiginous pattern, with cytologic hypertrophy, dendritic morphology, and hypermelaninization. These changes were evident in approximately 20-30% of nevi where they were absent before transplantation, suggesting that host factors, such as those related to the immune response, had stimulated growth. Graft survival was independent of nevus size and initial histologic diagnosis. No melanomas developed in any of the grafts, either spontaneously or with ultraviolet irradiation. These results indicate that successful transplantation can be achieved in a high proportion of human nevus xenografts and that the majority survive for a period of time that would be sufficient for experimental studies. The host response, however, has effects on intraepidermal melanocytic growth that lead to progressive fibrous replacement of the nevus, introducing significant artifacts that compromise the model. Furthermore, malignant transformation of engrafted melanocytes seems to be a rare event, which would limit studies of neoplastic progression in the transplanted melanocytes. Nonetheless, the intraepidermal melanocytic pattern described here evidently constitutes one pattern of melanocyte growth that could be exploited experimentally for studies of growth and differentiation control in melanocytes.     

In situ distribution of integrin alpha 2 beta 1 and alpha-actinin in melanocytic proliferations

Integrin alpha 2 beta 1 is a transmembrane protein receptor for collagen and laminin previously reported as a melanoma tumor progression antigen. alpha-Actinin is an actin-binding protein reported to interact with the cytoplasmic domain of the beta 1-integrin chain of alpha 2 beta 1. In vitro, both alpha 2 beta 1 and alpha-actinin play a role in melanoma cell motility. In turn, increased melanoma cell line motility (measured as mean migration rates), correlates with metastasis. To determine the in situ distribution of these proteins, we used monoclonal antibodies directed against the alpha 2-integrin subunit of alpha 2 beta 1 and alpha-actinin on frozen sections of 33 melanocytic proliferations, which included dermal nevi, primary melanomas, and metastatic melanomas. We found that the superficial portion of all of the melanocytic proliferations tested stained for alpha-actinin. In benign nevi and superficial spreading melanoma, there was a notable loss of staining for alpha-actinin in the cells in the deep reticular dermis. In contrast, alpha-actinin was present on almost all of the tumor cells in the nodular melanomas and the melanoma metastases. Tumors stained either uniformly positive or uniformly negative for alpha 2 beta 1; the expression of this protein correlated with the later stages of melanoma progression. Our findings suggest that alpha-actinin protein levels initially decrease and then increase during melanocytic tumor progression, whereas the alpha 2 subunit protein appears in the later stages of melanoma progression. The variable distribution of these proteins is evidence for the differential adhesive and motile properties of subpopulations of cells in melanocytic proliferations.     

Nucleolar organizer regions in conjunctival nevi and melanomata

The objective of this study was to compare the argyrophil nucleolar organizer region (Ag-NOR) counts of conjunctival nevi and melanomata and to compare the efficacy of this method in their differential diagnosis. Nine histologically diagnosed conjunctival nevi and three conjunctival malignant melanomas were studied. Representative sections were stained using the AgNOR technique. Fifty cells of each melanocytic lesion were randomly selected without knowing their histologic diagnosis. The AgNORs were visualized at a magnification of x1000. They consisted of clusters >1 micron in diameter and of satellites <1 micron in diameter, which were counted and recorded for each cell separately. The mean AgNOR count for the nevi was 1.12 clusters and 1.72 satellites per cell, while the count for the melanomas was 1.6 clusters and 6.8 satellites per cell. These results are statistically significant. There was no overlap between the number of AgNOR clusters and satellites in conjunctival nevi and melanomas, indicating that the AgNOR count might be a useful tool in distinguishing benign from malignant conjunctival melanocytic lesions.     

Diagnosing and treating congenital melanocytic nevus simulating malignant melanoma

Many cases reported as malignant melanomas arising in benign congenital melanocytic nevi in the neonatal period have not shown evidence of metastases after several years of follow-up. These lesions were probably pathologically misdiagnosed, thus creating a controversy regarding the precise incidence. This article describes the case of an infant with a giant melanocytic nevus simulating malignant melanoma to illustrate the proper criteria for diagnosis of this condition so extensive and unnecessary therapy procedures can be avoided.     

Melanocytic nevi and risk of cutaneous malignant melanoma in southern Spain

The main objective of this study was to assess whether cutaneous malignant melanoma (CMM) shows a stronger relation with the melanocytic nevi count at the site where CMM was diagnosed than with the melanocytic nevi count at other sites, stratifying by histologic CMM type, in a southern Mediterranean population. Cases and controls were selected from a population in southern Spain in 1988-1993. The study population included 116 incident cases with non-familial CMM (International Classification of Diseases 9th Revision (ICD-9) code 172), and 116 controls matched 1:1 for sex and age (+/- 4 years). Data were collected by personal interview, and melanocytic nevi were counted over the entire body surface by clinical skin examination performed by a dermatologist. Crude and multiple risk factor-adjusted odds ratios and 95% confidence intervals were computed by conditional logistic regression analysis. After adjustment by skin type, unexposed skin color, and sun exposure, CMM was found to occur significantly more frequently in individuals with a high number of melanocytic nevi at the same site where CMM originated (odds ratio (OR) for >8 nevi = 12.0, 95% confidence interval (CI) 1.3-108.2). The ability to predict the number of melanocytic nevi on different anatomic sites on CMM, but excluding the CMM cases on each corresponding site, was also examined. A significant trend with the number of nevi on the anterior surface of thighs was found (OR for >4 nevi = 4.5, 95% CI 1.4-14.9). Melanocytic nevi count on the melanoma site was the variable most closely related to superficial spreading melanoma subtype (SSM) (OR for >8 nevi = 82.19, 95% CI 2.72-2,454). On the other hand, the number of melanocytic nevi on the melanoma site was unrelated to risk of CMM subtypes other than SSM. These results support the hypothesis that nevi are an important risk factor for melanoma, especially SSM, in populations with a darker ethnic background.     

Spindle and epithelioid cell nevi in children and adults. A review of 211 cases of the Spitz nevus

A large series of 211 Spitz nevi is reviewed. 30% of the lesions were from patients 20 years of age and over. The trunk and lower extremity were most commonly involved. There were no significant histologic differences between cases from adults and children. Features which may help in differentiating atypical Spitz nevi from malignant melanoma include the presence of some nevus cell maturity at the base, an absence of atypical mitoses, no significant upward epidermal spread and the nuclear chromatin pattern.     

Syndromes associated with melanocytic nevi

Melanocytic nevi have been reported in association with several congenital syndromes. This review describes the clinical and cutaneous manifestations of six syndromes associated with congenital melanocytic nevi, two associated with acquired nevi, and six associated with melanocytic nevi in which insufficient evidence exists to classify them as congenital or acquired. It is important to recognize these associations to evaluate and counsel patients with melanocytic nevi. Early recognition will also facilitate timely intervention.     

Vitamin D prophylaxis in children with a single dose of 150000 IU of vitamin D

INTRODUCTION: Blue nevi are small acquired melanocytic tumors. Two clinical forms are described, a fibrous form and a cellular form. Giant nevi are exceptional. CASE REPORT: We describe a patient with a giant blue nevus of the scalp. In addition to this congenital, noninvasive tumor the patient presented numerous cutaneous melanocytic nevi. The main lesion was removed by surgical exeresis followed later with reconstruction plasty. The histological examination of the surgical specimen showed an infiltrating blue cell nevi. After a 4-year follow-up, there has been no recurrence and no metastasis. DISCUSSION: There have been 11 cases of giant blue nevi reported in the literature. All were congenital lesions with polymorphous clinical and histological aspects. Fibrous forms are noninvasive and cellular forms have a potential for local invasion, whether shortly after birth or later with invasion of muscles, bone and meninges without intracerebral extension. Congenital blue nevi require early surgical exeresis.     

Adhesion molecule expression in normal skin and melanocytic lesions. Role of UV-irradiation and architectural characteristics in nevi

Cell adhesion between surfaces of cells and to extracellular matrices represents a fundamental mechanism in tissue organization and influences the biological behaviour and the architecture of tumors. We investigated the expression of various adhesion molecules in normal skin (n=5), nevi (n=29), and malignant melanoma (n=10) by immunohistochemistry. Special attention was paid to the correlation between adhesion molecule expression and the respective architectural features, e.g. UV-induced morphological changes, and the arrangement of melanocytes in congenital nevi. In nevi, a single erythemagenic dose of UV-light did not influence the integrin expression of melanocytes, but results in an upregulation of alpha3 beta1- and alpha6 beta1-integrin within the suprabasal layers of the epidermis. This suprabasal labelling was associated with an increased number of suprabasal melanocytes in UV-irradiated nevi which were detected with HMB-45 antibody. Nine of 10 congenital nevi demonstrated a labelling of alpha4 beta1-integrin only in melanocytes of the deeper dermis. This integrin previously has been associated with high tumor thickness and the clinical outcome in melanomas. The integrin profile observed in melanomas differed in part from that seen in nevi with expression of beta2- and beta3-integrins in some cases. The results may indicate a correlation between adhesion molecule expression and histopathological findings in melanocytic lesions.