Dysplastic nevi as precursors to hereditary melanoma

Role of Heredity in Melanoma Susceptibility: A Primer for the Practicing Surgeon

Melanoma is a deadly skin cancer linked to ultraviolet radiation exposure. Heritable traits and sporadic mutations modify an individual's risk for melanoma that may be associated with phenotype. Familial/heritable melanomas are broadly used to describe families with an increased incidence of melanomas, although the underlying mutation may be unknown. Mutations associated with melanoma occur in cell cycle regulation, tumor suppression, chromosomal stability, DNA repair, pigmentation, and melanocyte differentiation genes. Genetic testing of individuals with a family history of melanoma may provide additional etiologic information and ensure patients with known markers for cancer development are closely monitored by physicians.

State of melanoma: an historic overview of a field in transition

The last 30 years has seen a revolution in melanoma. Fundamental elements of the surgical, adjuvant medical, and systemic therapy for the disease have been significantly altered toward improved management and better outcomes. The intent of this article is to reflect on past efforts and research in melanoma and the current landscape of treatment of melanoma. The authors also hope to capture the excitement currently rippling through the field and the hope for a cure. The intent of treatment of advanced melanoma, which was once considered incurable, has changed from palliative to potentially curative.

A brief history of melanoma: from mummies to mutations

In recent years, melanoma research has undergone a renaissance. What was once viewed, at least in the metastatic setting, as an intractable and untreatable disease is now revealing its molecular weaknesses. 2011 was a landmark year for melanoma therapy, with two new agents, the anti-CTLA4 antibody ipilimumab and the BRAF inhibitor vemurafenib, shown to confer a survival benefit in randomized phase III clinical trials. Overlooked in the recent flurry of interest that has accompanied the development of these drugs, melanoma is in fact an ancient disease that has long frustrated attempts at therapeutic interventions. In this article, we trace the history of melanoma: from the earliest known cases of melanoma in pre-Colombian South America, through the explorations of the Victorian anatomists right up to the molecular biology revolution of the 20th century that allowed for the identification of the key driving events required for melanomagenesis. We further outline how observations about melanoma heterogeneity, first made over 190 years ago, continue to drive our efforts to reduce melanoma to the level of a chronic, manageable disease and ultimately to cure it entirely.

The frequency of histologically dysplastic nevi in 199 pediatric patients

Many uncertainties surround the definition, frequency, and significance of dysplastic nevi in children. Consequently the management of dysplastic nevi in the pediatric population has been largely derived from the studies of adults. Biopsies are usually performed on this young age group because of lesion change or abnormal appearance. One might therefore assume that the frequency of histologically diagnosed dysplastic nevi would be higher in children than in adults. We decided to attempt to verify this assumption by determining the frequency of dysplastic nevi diagnosed histologically in the pediatric population. To do this we reviewed 199 cutaneous pathology reports of nevi removed from patients less than 18 years old and submitted to a community-based dermatopathology laboratory. The diagnosis of dysplastic nevus was made based on histologic criteria recommended by the World Health Organization Melanoma Program. We found that 3 of 199 nevi submitted for histologic analysis met the histologic criteria for dysplastic nevus. There were no melanomas. Our data suggest that there is an extremely low frequency of histologically confirmed dysplastic nevi within the general pediatric population.

Case-control study of melanocytic nevi on the buttocks in atypical mole syndrome: role of solar radiation in the pathogenesis of atypical moles

BACKGROUND

It is not known why melanocytic nevi (MN) become dysmorphic (atypical) in patients with the atypical mole syndrome (AMS). A complex origin for acquired MN has been postulated. Genetic predisposition, solar radiation, and/or the formation of a sun-induced circulating mitogenic factor may contribute to the formation of MN.

OBJECTIVE

This study was undertaken to help elucidate the pathogenesis of atypical MN in patients with AMS.

METHODS

The number of common and atypical MN was determined for a defined sun-protected area on the buttocks in 150 patients with AMS (cases) and 150 control subjects without AMS. Patients and control subjects were matched for age and sex and were classified into risk groups for the development of malignant melanoma according to the Rigel classification.

RESULTS

MN on the buttocks were found in 23% of patients with AMS and 9% of control subjects (p < 0.003). In patients versus control subjects the mean number (1.3 vs 1.2, respectively) and mean diameter (5.7 vs 5.9 mm, respectively) of MN on the buttocks did not differ significantly. The MN in both patients and control subjects were not atypical clinically. The odds ratio for having AMS if MN were present on the buttocks was calculated to be 1.56 (95% confidence interval, 1.25 to 1.95).

CONCLUSION

Although the patients were 2.6 times more likely to have MN on their buttocks than the control subjects, clinically the MN did not differ significantly in number or appearance from those found on the buttocks of control subjects. It is hypothesized that the formation of some atypical MN requires direct solar radiation for their phenotypic expression.

Genetics of seven Dutch familial atypical multiple mole-melanoma syndrome families: a review of linkage results including chromosomes 1 and 9

Familial atypical multiple mole-melanoma syndrome is characterized by the familial occurrence of malignant melanoma of the skin in combination with multiple atypical precursor nevi; its pattern shows a dominant inheritance in pedigrees. During the last 5 years we have performed linkage analysis in seven Dutch familial atypical multiple mole-melanoma families to define the locus of the underlying gene defect. In 1989 it was reported that in familial melanoma families in the USA a disease-gene was located on chromosome 1p. However, in the Dutch families we could exclude this chromosome from harboring the Dutch familial atypical multiple mole-melanoma gene. Very recently a new candidate locus was found on chromosome 9p, which could be confirmed in our family material. A melanoma-associated gene was linked to several markers on chromosome 9p21. In a linkage analysis in which only melanoma patients were considered as affected, marker D9S171 showed a maximum lod score of 3.11 (theta 0.0). After introducing family members with 10 or more, or five or more, atypical nevi as affected in addition to the melanoma patients, the maximum lod score rose to 4.88 (theta 0.05) and 3.79 (theta 0.07), respectively. Interestingly, the sharing of a unique chromosome 9p21 haplotype among most melanoma patients in the families from two different villages suggests that an old common mutation is present in the Leiden region.

Role of beta 1 integrins in cell spreading and migration of human nevomelanocytes and dysplastic nevi cells on collagen type IV and laminin

We characterized beta 1 integrin subunit expression on three different cultures of benign human nevomelanocytes (NMC) and on four different cell cultures of human dysplastic nevus (DN) cells by flow cytometry analysis and examined their role in mediating cell spreading and migration on collagen type IV (CN IV) and laminin (LN) coated substrates by using a quantitative video image analysis system. The seven human NMC and DNC cultures expressed heterogeneous levels of beta 1, alpha 2, alpha 3 and alpha 6 integrin subunits. Image analysis showed that a significant increase (P < 0.001) in cell spreading and migration of the DN cells was induced on increasing coating concentrations of CN IV and LN. However, the NMC did not show an increase in cell spreading or migration on these substrates when compared to the substrates coated with denatured BSA only. The CN IV-induced cell spreading of the DN cells was significantly inhibited by anti-beta 1 mAb (AIIB2), anti-alpha 2 mAb (P1E6), or anti-alpha 3 mAb (P1B5), but not by mAb against alpha 6 integrin subunit (GoH3). The DN cell spreading on LN was not significantly inhibited by these mAbs. In contrast, the migration of the DN on CN IV and LN was significantly inhibited by anti-beta 1 mAb, anti-alpha 2 mAb, anti-alpha 3 mAb and anti-alpha 6 mAb. These data suggest that the alpha 2 and alpha 3 subunit are important for cell spreading of the DN on CN IV, although they are less important in cell spreading on the extracellular matrix component LN.(ABSTRACT TRUNCATED AT 250 WORDS)

Important melanocytic lesions in childhood and adolescence

Melanocytic nevi are common in children and adolescents, and the preponderance of these lesions are benign. Congenital melanocytic nevi, dysplastic nevi, and large numbers of common acquired nevi, however, may indicate an increased risk of malignant melanoma. With the exception, possibly, of giant congenital nevi, melanoma associated with these lesions generally occurs in adulthood. Nonetheless, some patients can be identified as being at increased risk for the development of melanoma during childhood. The poor prognosis associated with advanced melanoma and the curability of early lesions underscore the importance of prompt recognition of melanoma when it does occur in children. Furthermore, physicians who care for children are in a key position to decrease risk of melanoma throughout the lifespan by encouraging avoidance of excessive sun exposure during childhood.

Systemic cancer and the FAMMM syndrome

The FAMMM syndrome consists of the familial occurrence of cutaneous malignant melanoma and atypical nevi (dysplastic nevi), and is inherited as an autosomal dominant trait. Conflicting results have been reported on the question of whether the syndrome includes increased susceptibility to non-melanoma cancers. We have studied cancer of all anatomic sites and histologies in nine FAMMM families which were ascertained in a pigmented lesions clinic in the Netherlands. We evaluated two hypotheses: that the number of systemic cancers observed in the families was excessive, compared to expected incidence, based on Dutch incidence data, and that there was variation (or heterogeneity) among families in the frequency of systemic cancer. A significant excess of systemic cancer (especially digestive tract cancer) was observed. Significant heterogeneity was also found among the families; three of the nine families had marked excess in numbers of systemic cancers, and the remaining families had normal numbers of cancers among the known FAMMM gene carriers and their first degree relatives. Thus, we provide evidence of increased susceptibility to systemic cancer occurring in conjunction with the FAMMM syndrome in a subset of this resource.

Clinical characteristics of malignant melanomas developing in persons with dysplastic nevi

A total of 452 patients with dysplastic nevi (DN) were followed prospectively by repetitive, complete cutaneous examinations in order to determine the clinical features of early malignant melanomas (MM) arising in them. Sixteen patients (3.5%) developed 18 newly diagnosed MM during an average follow-up period of 27 months. Twelve of the 18 MM were in situ and all of the primary invasive MM diagnosed prospectively in this follow-up were less than 0.89 mm in Breslow thickness, implying an excellent prognosis. The principal clinical clue to the diagnosis of MM was change in a preexisting pigmented lesion. Total-body photographs were very useful in helping to identify the early MM in these patients.

Melanoma in children

Four cases of malignant melanoma in children younger than 17 years of age are presented. Several preexisting conditions increase the risk of development of melanoma during childhood. These include giant congenital melanocytic nevi, the familial dysplastic nevus syndrome, and xeroderma pigmentosum. The role of small congenital lesions and sporadic dysplastic nevi in the development of melanoma in children is less clear. The signs and symptoms associated with melanoma in children are similar to those in adults, as are the histopathologic features, biologic behavior, and treatment of this tumor. The inadequacy of available therapy for metastatic melanoma underscores the necessity for the early diagnosis and prompt surgical treatment of melanomas in children.

Dysplastic nevi. Markers for increased risk for melanoma

A total of 452 white patients, classified into four dysplastic nevi groups, were followed prospectively by repetitive, complete cutaneous examinations using total-body photographs taken on entry into the study. Sixteen patients (3.5%) developed 18 newly diagnosed malignant melanomas (MM) during an average follow-up period of 27 months. Twelve of the 18 MM were in situ, and all of the six primary invasive MM diagnosed prospectively in this follow-up were less than 0.89 mm in Breslow thickness, implying an excellent prognosis. Compared with reference populations, the number of MM detected significantly exceeded the number estimated to occur in the comparable age-matched control groups. These data support the concept of repetitive follow-ups of all groups of patients with dysplastic nevi.

Clinical diagnosis of dysplastic melanocytic nevi. A clinicopathologic correlation

A prospective, community practice-based, clinicopathologic correlation was undertaken in 165 melanocytic nevi excised from a group of forty-three patients, each patient having previously had at least one clinically suspected and histologically confirmed dysplastic melanocytic nevus. Eighty-two percent of seventy-two lesions with histologic evidence of mild dysplasia had been diagnosed correctly as such clinically. The accuracy of clinical diagnosis of moderate dysplasia was low (20%); however, all cases of severe dysplasia with or without in situ melanoma were diagnosed correctly. In 75% of all cases in which dysplasia of any degree was diagnosed clinically, histologic evidence of dysplasia was found. In order to investigate further the clinical features of these nevi, 175 color enlargements of histologically confirmed dysplastic melanocytic nevi were examined. The following clinical features were found to be most common: ill-defined border (90%), irregularly distributed pigmentation (84%), maximum diameter greater than 5.0 mm (72%), erythema (64%), and accentuated skin markings (63%). Increasing darkness and confluence of pigmentation in these dysplastic melanocytic nevi correlated with increasing severity of dysplasia. We conclude that careful clinical examination of individual melanocytic nevi will separate severe dysplasia with or without in situ melanoma from low-grade (mild or moderate) dysplasia in a high percentage of nevi from patients with the dysplastic nevus syndrome. Clinical examination will yield a diagnosis of dysplasia in approximately 75% of nevi from such patients in whom histologic evidence of dysplasia is present. Clinical examination constitutes a practical and sufficiently reliable method for the assessment of melanocytic nevi in patients with the dysplastic nevus syndrome.

Malignant melanoma--its precursors and its topography of proliferation. DNA-Feulgen-cytophotometry and mitosis index

DNA-content and size of the nuclear areas in different zones of malignant melanomas of different histological types and in dysplastic naevi were measured in order to provide information on the histogenesis and proliferative behaviour of human malignant melanoma. The results were compared with those from normal epidermis, common naevi, and reactive melanocytic hyperplasias. The mitotic index of melanomas--divided into different topographic zones in an analogous way--was also determined. The DNA-histographs of all naevi and reactive melanocytic hyperplasias showed a diploid maximum, but the dysplastic naevi had a larger proportion of nuclei with hyperdiploid and tetraploid DNA-content, indicating an increased proliferative activity. The mean values (X) of nuclear areas in dysplastic naevi (DN) were about the same as in common naevi (CN) and slightly lower than in superficial spreading melanomas (SSM). The coefficient of variability (cv) as an indicator of anisokaryosis was markedly higher in DN (27.8) and SSM (29.3) than in CN (20.2). In DNA-content we found similar results: almost no difference in mean values, but DN taking an intermediate position between CN and SSM with respect to cv (CN: 12.3; DN: 21.0; SSM: 36.6). There was no unequivocal evidence in these data for DN being a precancerous stage. Superficial melanomas with a nodular component ("SSM/NM") differed from SSM and NM by increased DNA-content and greater variability of nuclear areas and showed the clearest features of malignancy in their DNA-histographs. The mitotic indices had rather low values in SSM and intraepidermal marginal zones of "SSM/NM" on one hand and markedly higher values in NM and nodular parts of "SSM/NM" on the other. The highest mitotic counts were found in the three investigated metastases.

Age distribution and histologic patterns of dysplastic nevi

A total of 676 dysplastic moles collected from 487 patients over a 1-year period were reviewed together with demographic data. The associated nevus in 642 cases (95%) had a superficial, or "acquired," pattern within the papillary dermis, in comparison with the nevus in the remaining 34 cases (5%), which showed a deep, or "congenital," pattern. The dysplasia was graded in severity as mild, moderate, or severe (on a scale of 1 to 3). When patients with mild to severe dysplastic melanocytic nevi were compared with those patients showing atypical intraepidermal melanocytic hyperplasia (also called in situ malignant melanoma) or early invasive malignant melanoma associated with dysplasia, a progression of ages was noted. The average ages in the five diagnostic groups were as follows: 34.8 years, mild dysplasia (group 1); 35.1 years, moderate dysplasia (group 2); 41.5 years, severe dysplasia (group 3); 44.4 years, in situ malignant melanoma (group 4), and 46.9 years, early invasive malignant melanoma (group 5). Statistical analysis revealed that the two younger groups differed significantly in age from the three older groups. Men and women had an equal proportion of acquired and congenital pattern nevi, but men were older in each category and had more severe dysplasia, a greater tendency toward truncal lesions, and more regressive changes. Biopsy of trunk lesions was done in 275 cases (80%), of extremity lesions in 60 cases (17%), and in head and neck sites in 9 cases (3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Fine structural characterization of melanosomes in dysplastic nevi

This study characterized the fine structure of melanosomes in melanocytes of the dysplastic nevi in six cases with lentiginous melanocytic dysplasia and one case with epithelioid-cell melanocytic dysplasia, and compared that structure with those of common melanocytic nevi and malignant melanoma. It was found that: fine structural features of melanosomes in dysplastic melanocytes were similar in these two histologic variants, and they were markedly aberrant and quite different from those of common melanocytic nevi; the aberrant melanosomes could be grouped into four subtypes, type 1 melanosomes corresponding to ellipsoidal-lamellar melanosomes, type 2 to spherical-incompletely lamellar melanosomes, type 3 to spherical-granular melanosomes, and type 4 to spherical-vacuolated melanosomes; type 2, 3, and 4 melanosomes were seen in all seven cases although their substructures and numbers varied in individual cases; and these type 2, 3, and 4 melanosomes were not seen in epidermal melanocytes of common melanocytic nevi, but were characteristically seen in superficial spreading melanoma and nodular melanoma. The findings indicated that the fine structural changes in synthesis and melanization of melanosomes are unique to the dysplastic nevi and that they may be helpful in diagnosis of the nevi and may fill the gap of abnormal melanogenesis that exists between common melanocytic nevi and malignant melanoma.