Nevogenesis-New Thoughts Regarding a Classical Problem

Metabolomic analysis reveals the biological characteristics of giant congenital melanocytic nevi

Giant congenital melanocytic nevi (GCMN) is a congenital cutaneous developmental deformity tumor that usually occurs at birth or in the first few weeks after birth, but its pathogenesis is still unclear. In this study, nuclear magnetic resonance-based metabolomics strategy was employed to evaluate the metabolic variations in serum and urine of the GCMN patients in order to understand its underlying biochemical mechanism and provide a potential intervention idea. Twenty-nine metabolites were observed to change significantly in serum and urine metabolomes, which are mainly involved in a variety of metabolic pathways including glyoxylate and dicarboxylate metabolism, TCA cycle and metabolisms of amino acids. The substantial cores of all the disturbed metabolic pathways are related to amino acid metabolism and carbohydrate metabolism and regulate the physiological state of the GCMN patients. Our results provide the physiological basis and physiological responses of GCMN and will be helpful for better understanding the molecular mechanisms of GCMN in future research.

Evaluation and management of benign tumors of the eye and eyelid

Benign tumors of the eye and eyelid are common in children and adults, and they rarely undergo malignant transformation. Their workup and management have evolved over the years with increasing advancements in surgical and laser therapies. This contribution focuses on describing the following benign eye and eyelid tumors and their diagnostic and treatment approaches: congenital and acquired melanocytic nevi; nevus of Ota (Hori nevus); conjunctival papilloma; seborrheic keratosis; epidermoid cyst; dermoid cyst; milium; xanthelasma; hemangioma (cherry angioma and pyogenic granuloma); neurofibroma; neurilemmoma (schwannoma); and fibroepithelial polyp. Surgical removal is the primary treatment approach for many of these benign tumors. With advancements in laser technologies, there are now several laser types that can be used in the treatment of these benign eye and eyelid tumors. Other treatment modalities include cryosurgery, electrosurgery, and topical or intralesional medications. We hope this review will provide a reference to dermatologists and ophthalmologists in their approach to evaluation and management of benign eye and eyelid tumors.

Differentiating between early melanomas and melanocytic nevi: A state-of-the-art review

Clinicians and dermatologists are challenged by accurate diagnosis of melanocytic lesions, due to melanoma's resemblance to benign skin conditions. Several methodologies have been proposed to diagnose melanoma, and to differentiate between a cancerous and a benign skin condition. First, the ABCD rule and Menzies method use skin lesion characteristics to interpret the condition. The 7-point checklist, 3-point checklist, and CASH algorithm are score-based methods. Each of these methods attributes a score point to the features found on the skin lesion. Furthermore, reflectance confocal microscopy (RCM), an integrated clinical and dermoscopic risk scoring system (iDscore), and a deep convoluted neural network (DCNN) also aids in diagnosis. RCM optically sections live tissues to reveal morphological and cellular structures. The skin lesion's clinical parameters determine iDscore's score point system. The DCNN model is based on a detailed learning algorithm. Therefore, we discuss the conventional and new methodologies for the identification of skin diseases. Moreover, our review attempts to provide clinicians with a comprehensible summary of the wide range of techniques that can help differentiate between early melanomas and melanocytic nevi.

[Current recommendations for congenital melanocytic nevi]

Congenital melanocytic nevi are pigmented birthmarks, some of which have a considerable size. In some cases, not only the skin but also the brain or spinal cord are affected. Many aspects about how to manage this disease have been reconsidered and partly changed over the last 20 years. This article summarizes the current state of knowledge and treatment recommendations.

Intramucosal Melanocytic Nevi - A Rare Cause for Gingival Enlargement. Report of a Case and Review of Literature

Background

Oral melanocytic nevi are infrequent oral lesions derived from nevus cells of oral mucosa which causes focal hyperpigmentation. The most common site of occurrence of oral nevi is the hard palate followed by buccal mucosa and gingiva. The mean age group affected are in their 3rd and 4th decade of life and there seems to be a predilection for females. Clinically, oral nevi are usually small, well-circumscribed macules but can also present as slightly raised papules. Histologically, nevi can be classified as Junctional, Compound or Intramucosal, with intramucosal being the more common type in the oral cavity.

Case Presentation

In this paper, we report a case of intramucosal nevus in a 25-year-old female patient. The lesion presented as a gingival enlargement in the mandibular anterior region involving the marginal and attached gingiva, which is an extremely rare presentation. The clinical findings, histologic features and surgical management are presented. The patient was followed up for one year and the one year follow up revealed a small area of focal hyperpigmentation at the site of the previous lesion which is being closely monitored.

Conclusion

Nevi located in the mucous membrane have been documented to pose a threat of malignant transformation. Hence, all pigmented lesions of the oral cavity should be cautiously diagnosed.

Pigmented Lesions in Children: Update on Clinical, Histopathologic and Ancillary Testing

Patients are commonly referred to pediatric dermatology for the evaluation of pigmented lesions. For families, pediatricians, and dermatologists alike, malignancy is the main fear. In the past few decades, there has been evolving literature to inform diagnosis and management. This article provides an update on the clinical, histopathologic, and ancillary testing for 3 categories of particularly challenging pigmented lesions: congenital melanocytic nevi, spitzoid neoplasms, and pediatric melanoma.

Clinicopathological Analysis of Acquired Melanocytic Nevi and a Preliminary Study on the Possible Origin of Nevus Cells

BACKGROUND

The pathogenesis of acquired melanocytic nevi (AMN) is still unclear, and the origin of nevus cells has not been clarified.

OBJECTIVE

To analyze the clinical features and pathological types of AMN and identify the possible origin of nevus cells.

METHODS

A retrospective study of 2929 cases of AMN was conducted, and 96 specimens of intradermal and junctional nevi were selected. Immunohistochemical assays were performed to detect the expression of basement membrane component receptor DDR-1 and the molecular markers on epidermal melanocytes, dermal stem cells (DSCs), and hair follicle stem cells.

RESULTS

Junctional nevi and compound nevi were prone to occur on glabrous skin, such as the palms, soles, and vulva, and on the extremities in children, whereas intradermal nevi tended to develop on the trunk, head, and face of adults. The immunohistochemical data revealed that both junctional nevi and intradermal nevi expressed the epidermal melanocyte surface markers E-cadherin, DDR-1, and integrin α6 and the DSC molecular markers NGFRp-75 and nestin. CD34 was expressed only in junctional nevi, whereas K19 was not expressed in any type of melanocytic nevi. There was no significant difference in molecular expression at different sites or in different ages of onset. Nestin expression was markedly stronger in the intradermal nevi than in the junctional nevi, but there was no difference between the superficial and deep nevus cell nests of intradermal nevi.

CONCLUSION

AMN may have a multicellular origin that commonly follows the mode of Abtropfung. Furthermore, DSCs may partly or independently participate in the formation of nevus cells.

A case of adult-onset longitudinal melanonychia due to nail matrix compound nevus

A case of adult-onset longitudinal melanonychia caused by a compound nevus is described. Longitudinal melanonychias are mainly caused by melanocytic activation (hypermelanosis), lentigo (benign melanocytic hyperplasia), nevus, and melanoma. Nevi are more commonly seen in children than adults; however, melanocytic activation, atypical melanocytic proliferation, and melanoma are more frequent in adults. The majority of nail matrix nevi causing longitudinal melanonychia first appear in childhood and are junctional. Rarely, compound nevi are reported to cause longitudinal melanonychia in childhood.

Cosmetically Challenging Congenital Melanocytic Nevi

BACKGROUND

Congenital melanocytic nevi (CMN) have a 1% to 5% lifetime risk for malignant transformation, with 50% of transformations occurring before the age of 5 years.The aim of this study is to assess the risk of melanoma development in pediatric patients with facial CMN involving the eyebrows, eyelid margins, and nasal alae where a margin of CMN was not excised to preserve these structures.

METHODS

A retrospective chart review of all pediatric patients with CMN from 1986 to 2014 was performed to review demographic information, diagnosis, and number of surgeries. Patients' clinical photographs were evaluated for residual nevi after completion of the treatment.

RESULTS

More than 950 medical charts of patients with CMN of the face area were reviewed. We identified 32 patients (13; 41% male) that met the study criteria with pathology-confirmed diagnosis of facial CMN with an average age of 4.4 years (3.3 months-15.8 years) at the time of initial surgery. The CMNs were classified into small (1; 3%), medium (14; 44%), large (14; 44%), and giant (3; 9%) based on their projected adult sizes. No patients developed melanoma within the small residual lesions left over the eyebrows and eyelids and inside nostrils at an average follow-up time of 5.6 (1.0-14.4) years and average age of 9.6 (1.8-19.2) years at the time of last follow-up.

CONCLUSIONS

Although a lifelong risk of malignant transformation of the residual CMN cannot be concluded, our results found no transformation in follow-up visits at an average age beyond the highest risk of melanoma development in childhood. We feel that leaving residual lesions on the face in areas of important anatomic structures for better cosmetic outcome is an acceptable risk.

Black and Brown Oro-facial Mucocutaneous Neoplasms

Black and brown-colored mucocutaneous lesions present a differential diagnostic challenge, with malignant melanoma being the primary clinical concern. The vast majority of pigmented lesions in the head and neck region are the result of benign, reactive factors such as post-inflammatory melanosis. However, it is not uncommon to discover a range of muco-cutaneous black and brown neoplasms in the oro-facial area. The majority of black/brown pigmented neoplasms are melanocytic in origin; these are neoplasms of neural crest derivation. Melanocytic nevi are a diverse group of benign neoplasms that are the result of specific oncogenic mutations. They are common on cutaneous surfaces but can manifest in mucosal sites. Currently, nevi are classified based on clinical and histological criteria. The most common cutaneous and oral mucosal nevus is the acquired melanocytic nevus; nevi do not pose an increased risk for the development of malignant melanoma. Emerging information on specific genetic differences supports the notion of biologically distinct nevi. This article will review the classic clinical and microscopic features of nevi commonly found in the head and neck region, and discuss emerging concepts in nevus pathogenesis and taxonomy. Melanoma is a malignant melanocytic neoplasm and is a result of cumulative genetic deregulation. The etiology of malignant melanoma (MM) is multifactorial and includes underlying genetic susceptibility, UV radiation, skin-type, and race. The majority of MM occurs on cutaneous surfaces and less commonly on mucosal and extra-cutaneous visceral organs. Regardless of location, MM exhibits clinical-pathological features that relate to horizontal or vertical tumor spread. Cutaneous and mucosal MM typically present as asymmetrical, irregularly bordered, large (> 0.5 cm), heterogeneous brown-black lesions with foci of erythema, atrophy or ulceration. As with melanocytic nevi, advances in melanomagenesis research have revealed primary oncogenic BRAF and NRAS mutations associated with cutaneous MM. Unlike their cutaneous counterparts, mucosal melanomas exhibit primary oncogenic alterations in c-KIT and other genes. This article will discuss the role of specific primary oncogenic and secondary/tertiary genetic defects in differential clinical presentation, anatomic distribution, future classification changes, and targeted therapy of melanoma. The clinical and microscopic features of mucosal melanomas and a summary of management guidelines will be discussed. Additionally, this article will cover the salient features of melanocytic neuroectodermal tumor of infancy, a neoplastic entity that can involve the oro-facial region, and the clinical-pathological features of selected, commonly occurring pigmented ectodermally-derived neoplasms that are often part of the clinical differential diagnosis of black-brown pigmented lesions.

Tyrosinase and nestin immunohistochemical expression in melanocytic nevi as a histopathologic pattern to trace melanocyte differentiation and nevogenesis

While histological analysis represents a powerful tool for the classification of melanocytic lesions as benign or malignant, a clear-cut distinction between a nevus and a melanoma is sometimes a challenging step of the diagnostic process. The immunohistochemical detection of tyrosinase, cardinal melanogenic enzyme during melanocytic maturation, has often been helpful in formulating a differential diagnosis due to the peculiar staining pattern in nevocytes compared with melanoma cells. Tyrosinase distribution in nevi appears to overlap with the cytoarchitectural changes observable within these lesions, that result in epidermal or superficial dermal nevocytes being larger and strongly expressing melanocytic differentiation antigens, such as tyrosinase, compared with deeper dermal nevus cells. Our study aimed to evaluate the immunohistochemical expression pattern of tyrosinase in different histological types of acquired dysplastic melanocytic nevi, including junctional, compound, and intradermal nevi. Moreover, to estimate whether in nevocytes the expression of tyrosinase was associated with their differentiation state, we investigated the expression of two recognized markers of pluripotency, CD34 and nestin. In all examined nevi, our analysis revealed a remarkable immunoreactivity for tyrosinase in junctional and superficial dermal nevocytes and a decreasing gradient of staining in dermal nevocytes, up to become negative in deeper dermis. Meanwhile, junctional and dermal nevocytes were lacking in CD34 protein. Furthermore, nestin immunostaining showed an opposite distribution compared with tyrosinase, leading us to look into the tyrosinase/nestin expression pattern in melanocytic nevus as a tool to better understand the final stages of differentiation of melanocyte precursors toward their ultimate anatomical site into the epidermis.

Acquisition of Somatic NRAS Mutations in Central Nervous System Melanocytes: A Predisposing Risk Factor to Primary Melanoma of the Central Nervous System, a Frequently Forgotten Pitfall in Congenital Nevi

Congenital melanocytic nevi (CMN) are benign melanocytic proliferations that are usually present at birth. A somatic mosaicism for an NRAS point mutation is responsible for the several phenotypic abnormalities that may be associated with congenital nevi. We report the case of a 7-year-old boy with a proliferative nodule (PN) arising in a Giant CMN completely excised and with several visceral and intraspinal melanoma metastases with no evidence of primary cutaneous melanoma. The careful analysis of the clinical, morphologic, and molecular features allowed the distinction of between the benign PN (BPN) and the melanoma. The BPN showed a characteristic comparative genomic hybridization pattern with gains or losses of whole chromosomes, whereas the melanoma displayed gains or losses involving complex partial chromosomal copy number gains or losses. Leptomeningeal melanocytes are more susceptible to transformation by oncogenic NRAS than cutaneous melanocytes, and central nervous system melanomas are more common than cutaneous melanomas in the setting of CMN. Thus, it has been recommended to characterize the congenital disease in patients with 2 CMN at birth, independently of size and site, with a single magnetic resonance imaging screening younger than the age of 1 year.

Dermoscopic patterns of melanocytic nevi in children and adolescents: a cross-sectional study

Background

Childhood is a dynamic period regarding nevogenesis. Dermoscopy is a noninvasive technique, recommended for the evaluation of pigmented cutaneous lesions.

Objectives

The purpose of this study was to describe the structures and dermoscopic patterns of melanocytic nevi observed in children and adolescents.

Methods

Dermoscopy with photographic documentation was used for nevi located on the face, trunk, and extremities of 38 patients aged from one to 16 years examined at the Pediatric Dermatology Outpatient Clinic of the Federal University of São Paulo.

Results

The study included 201 skin lesions that were diagnosed as nevi during clinic examination. Upon evaluation of the global dermoscopic pattern of the lesions, the most frequently observed nevi were reticular (39.0%), followed by homogeneous (23.9%) and globular nevi (16.4%). During evaluation of the dermoscopic structures, according to the body site, the pigment network was the most observed in the extremities.

Study limitations

A limitation to be considered is that the inclusion of small or new lesions may hinder the differentiation between dots and globules.

Conclusions

In our study, the most observed pattern was reticular. There was a difference in the predominance of structures dependent on the anatomical location.

Medium Sized Congenital Melanocytic Nevus with Suspected Progression to Melanoma during Pregnancy: What's the Best for the Patient?

BACKGROUND:

Congenital melanocytic nevi (CMN) are pigmented skin lesions usually present at birth. Rare varieties can develop and become clinically very large. Although they are benign nevomelanocytic neoplasms, all CMN may be precursors of the melanoma, regardless of their size. Individual risk of malignant transformation of melanocyte is determined by simultaneous action of exogenous and endogenous factors. The major exogenous risk factor is ultraviolet radiation. Leading roles among the endogenous factors are attributed to skin phenotype, gene mutation, sex hormones and their significance.

CASE REPORT:

We present a case of a 27 – year - old pregnant female patient with a congenital melanocytic nevus, which increased significantly in size, during her pregnancy. Estrogen levels increase during pregnancy and clinical evidence has suggested that melanocytes are estrogen - responsive. Nevi in a pregnant patient would exhibit increased expression of estrogen receptor β (ERβ) and thus enhanced the potential to respond to altered estrogen levels.

CONCLUSION:

All pigmented skin lesions should be carefully observed during pregnancy by a dermatologist due to the increased risk of malignant transformation, associated with the endocrine dependence. All lesions with visible changes should be removed surgically with appropriative anaesthesia.

Intense Pulsed Light Alone and in Combination with Erbium Yttrium-Aluminum-Garnet Laser on Small-to-Medium Sized Congenital Melanocytic Nevi: Single Center Experience Based on Retrospective Chart Review

Background

Treatment of congenital melanocytic nevi (CMN) with intense pulsed light (IPL) has recently produced promising results.

Objective

To evaluate the clinical and histological outcomes of small-to-medium sized CMN treated with IPL alone and in combination with erbium: yttrium-aluminum-garnet (Er: YAG) laser.

Methods

We performed a retrospective chart review of 26 small-to-medium sized CMN treated as described above. The reduction in visible pigmentation, signs of recurrence and any adverse skin changes were evaluated by two independent clinicians.

Results

Seventeen patients completed treatment and were followed-up. Nine were not able to complete treatment due to work, change in residence, and treatment related stress. Ten patients received IPL alone (mean: 10.5 sessions) and 7 underwent treatment with IPL (mean: 7.7 sessions) and Er: YAG/IPL combination therapy (mean: 4.7 sessions). The initial treatment outcome was cleared in 5 patients and excellent in 12. Fourteen patients (82.4%) showed CMN recurrence one year after treatment completion. The histological results from a patient with an excellent clinical outcome showed remnant nevus cells nests in the deep dermis.

Conclusion

IPL treatment alone and in combination with Er: YAG laser are not definitive treatments for CMN and should not be considered as first-line treatment.

The study of nevi in children: Principles learned and implications for melanoma diagnosis

Melanocytic nevi are a strong phenotypic marker of cutaneous melanoma risk. Changes in nevi during childhood and adolescence make these prime periods for studying nevogenesis. Insights gained by the study of nevi in childhood have implications for melanoma detection in both adults and children. A more comprehensive understanding of the morphologic characteristics of nevi in different anatomic locations, in association with the patient's age and pigmentary phenotype may aid in the identification of melanomas. When monitoring melanocytic lesions over time, it is essential to differentiate normal from abnormal change. This review summarizes the rapidly expanding body of literature relevant to nevus phenotype, particularly in the context of our experience with the Study of Nevi in Children (SONIC) Project.

Cross-sectional analysis of the dermoscopic patterns and structures of melanocytic naevi on the back and legs of adolescents

BACKGROUND

Junctional (flat) naevi predominate on the extremities, whereas dermal (raised) naevi are found primarily on the head, neck and trunk. Few studies have investigated the anatomical site prevalence of melanocytic naevi categorized using dermoscopy.

OBJECTIVES

To identify the prevalence of dermoscopic patterns and structures of naevi from the back and legs of adolescents.

METHODS

Dermoscopic images of acquired melanocytic naevi were obtained from the back and legs of students from a population-based cohort in Framingham, Massachusetts. Naevi were classified into reticular, globular, homogeneous or complex dermoscopic patterns. Multinomial logistic regression modelling assessed the associations between dermoscopic pattern and anatomical location.

RESULTS

In total 509 participants (mean age 14 years) contributed 2320 back naevi and 637 leg naevi. Compared with homogeneous naevi, globular and complex naevi were more commonly observed on the back than the legs [odds ratio (OR) 29·39, 95% confidence interval (CI) 9·53-90·65, P < 0·001 and OR 6·8, 95% CI 2·7-17·14, P < 0·001, respectively], whereas reticular lesions were less likely to be observed on the back than on the legs (OR 0·67, 95% CI 0·54-0·84, P = 0·001). Naevi containing any globules were more prevalent on the back than on the legs (25% vs. 3·6%, P < 0·001). Naevi containing any network were more prevalent on the legs than on the back (56% vs. 40·6%, P < 0·001).

CONCLUSIONS

These findings add to a robust body of literature suggesting that dermoscopically defined globular and reticular naevi represent biologically distinct naevus subsets that differ in histopathological growth pattern, age- and anatomical-site-related prevalence, molecular phenotype and aetiological pathways.

Melan-A positive dermal cells in malignant melanoma in situ

The presence of Melan-A positive dermal cells in excisions for melanoma in situ represents a frequent conundrum for pathologists. These cells may represent superficially invasive melanoma, benign, incidental, dermal nevi or non-specific staining of dermal melanophages. Occasionally, rare, Melan-A positive dermal cells are present which do not clearly correspond to the above three categories. Our objective was to further characterize these Melan-A positive dermal cells. To do this, immunoperoxidase staining for Melan-A and SOX-10 was performed on 188-cutaneous excisions, including examples of melanoma in situ, atypical junctional melanocytic hyperplasia and non-melanocytic tumors. These were evaluated for the presence of Melan-A and SOX-10 positive dermal cells. Dermal cells, positive for both markers, were identified in 17% of the excisions. The cells were present in 10% of cases from the melanocytic group and 31% of the cases from the non-melanocytic group. These cells did not exhibit cytologic atypia and resembled neither the co-existing neoplasm nor melanophages. We conclude that positivity of these rare Melan-A positive cells for SOX-10 argues that they represent true melanocytes and not non-specific staining. The absence of cytologic atypia in these cells and their presence in excisions of non-melanocytic neoplasms argues that they are benign, reactive, dermal melanocytes.

Giant congenital melanocytic nevi and neurocutaneous melanosis

Introduction. The major medical concern with giant congenital melanocytic nevi CMN is high risk of developing cutaneous melanoma, leptomeningeal melanoma, and neurocutaneous melanocytosis. Case Report. A 30-year-old woman with a giant congenital melanocytic nevus covering nearly the entire right thoracodorsal region and multiple disseminated melanocytic nevi presented with neurological symptoms. Cerebral magnetic resonance imaging revealed a large expansive lesion in the left frontal region. Postsurgically pathological diagnosis revealed characteristics of melanoma. Immunohistochemical examination showed S100(+), HMB45(+), MelanA(+), and MiTF(+). She received radiotherapy with temozolomide followed by two more chemotherapy cycles with temozolomide. She followed a rapidly progressive course, reflecting widespread leptomeningeal infiltration, and she died of multiorgan failure seven months after diagnosis of cerebral melanoma. Discussion. This patient was diagnosed as having a neurocutaneous melanosis with malignant widespread leptomeningeal infiltration. Diffuse spinal involvement is unusual and is described in only another patient.

Case reports of fatal or metastasizing melanoma in children and adolescents: a systematic analysis of the literature

Childhood melanoma (ChM) is rare, with clinical and epidemiologic characteristics that differ from those of adult melanomas. The objective of the current study was to systematically identify and analyze case reports and case series of fatal and metastasizing ChM in the medical literature. ChM case reports with a fatal outcome or metastases were identified using a Medline search and subdivided into ChM developing in the absence of a congenital melanocytic nevus (ChM without CMN) and ChM associated with a CMN (ChM with CMN); 258 cases of ChM without CMN (206 cutaneous, 52 noncutaneous) were identified. In cutaneous ChM without CMN with a fatal outcome (n = 155), the mean age at diagnosis was 13.1 years (median 14 yrs). The mean Breslow index in this group was 8.5 mm for children ages 0 to 10 years and 3.7 mm for children ages 11 to 18 years. In ChM with CMN (n = 178; 112 cutaneous, 66 central nervous system [CNS]), the mean age at diagnosis was 5.8 years for cutaneous melanoma (median 3 yrs) and 5.5 years for CMN-associated CNS melanoma (median 3 yrs). The majority of CMN-associated cutaneous melanomas developed in small and giant CMN (vs medium and large); 53.9% of CNS melanomas developed in patients with multiple medium CMN. This study represents the largest and most complete synopsis of ChM case reports in the medical literature. Our analysis supports the view that cutaneous ChM without CMN (or associated with smaller CMN) differs in several important aspects from ChM associated with large or giant CMN.

Update on Molecular Pathology of Cutaneous Melanocytic Lesions: What is New in Diagnosis and Molecular Testing for Treatment?

In this article, we give an update on recent findings regarding molecular pathology in cutaneous melanocytic tumors. The focus lies on use of genetics in the diagnosis of distinct subtypes of spitzoid tumors that are often characterized by specific phenotypic–genotypic alterations that can frequently be recognized by adequate histological examination. Typical illustrating cases are given in order to increase recognition of these lesions in daily dermatopathology practice. New molecular findings in the pathogenesis of congenital melanocytic tumors and neurocutaneous melanosis are reviewed. In addition, use of mutation analysis in the differential diagnosis of melanoma metastasis is discussed. Finally, application of mutation analysis in targeted therapy in advanced melanoma with advantages of new techniques such as next generation sequencing is described.

Clonogenic cell subpopulations maintain congenital melanocytic nevi

Large congenital melanocytic nevi (lCMN) are benign melanocytic tumors associated with an increased risk of melanoma transformation. They result predominantly from a post-zygotic somatic NRAS mutation. These lesions persist and even increase after birth proportionally to the child's growth. Therefore, we asked here whether cells with clonogenic and tumorigenic properties persisted postnatally in lCMN. Subpopulations of lCMN cells expressed stem cell/progenitor lineage markers such as Sox10, Nestin, Oct4, and ABCB5. In vitro, 1 in 250 cells from fresh lCMN formed colonies that could be passaged and harbored the same NRAS mutation as the original nevus. In vivo, lCMN specimens xenografted in immunocompromised mice expanded 4-fold. BrdU(+)-proliferating and label-retaining melanocytes were found within the outgrowth skin tissue of these xenografts, which displayed the same benign nested architecture as the original nevus. lCMN cell suspensions were not able to expand when xenografted alone in Rag 2-/- mice. Conversely, when mixed with keratinocytes, these cells reconstituted the architecture of the human nevus with its characteristic melanocyte layout, lentiginous hyperplasia, and nested architecture. Overall, our data demonstrate that, after birth, certain lCMN cell subtypes still display features such as clonogenic potential and expand into nevus-like structures when cooperating with adjacent keratinocytes.

Coexpression of SOX10/CD271 (p75(NTR)) and β-Galactosidase in Large to Giant Congenital Melanocytic Nevi of Pediatric Patients

Background

Congenital melanocytic nevi (CMNs) are melanocytic neoplasms that can transform into melanoma. However, this development is impeded in the majority of cases and mostly affects patients with large or giant CMNs.

Methods

To elucidate mechanisms that keep CMNs from malignant transformation, CMN tissue biopsies were investigated for p-ERK and senescence markers by immunohistochemistry and for SOX10/CD271 (p75^NTR) by immunofluorescence. CMN cells were cultivated, and MTT assays were performed for evaluating cell viability. Mutation status for NRAS and BRAF was performed by real-time PCR.

Results

13 CMNs (from patients aged 0.5-11.8 years, mean: 2.7) showed immunoreactivity for SOX10/CD271 (p75^NTR) in 34.2%. p-ERK was immunoreactive in 80% (4/5); β-galactosidase was significantly stronger expressed in CMNs compared to melanocytic nevi of patients over 70 years (p = 0.0085). The 5 CMN cultures were immunoreactive for SOX10/CD271 (p75^NTR) in 36.7%. By silencing SOX10 by siRNA in 2 CMN cell cultures, cell viability decreased significantly. NRAS^Q61K mutation was found in 91.7% (11/12) and BRAF^V600E in 6.3% of all analyzable CMNs (1/16).

Conclusions

Oncogene-induced senescence might prevent malignant transformation through activation of the mitogen-activated protein kinase pathway. SOX10 is necessary for the viability of human CMN cell cultures and may be responsible for clinical changes during aging.

Skin of patients with large/giant congenital melanocytic nevi shows increased mast cells

Nevocytes (NC) and mastocytes (MC) have different progenitors but share stem cell factor as regulator/activator of NC and for differentiation/proliferation of MC. Both cell types express stem cell factor receptor CD117. We hypothesize that large/giant congenital melanocytic nevi (L/GCMN) may associate with MC hyperplasia. Forty-nine L/GCMN were examined, 12 samples from uninvolved skin of L/GCMN patients and 6 control skin samples studied with Giemsa and immunohistochemistry for CD117 and MC-tryptase. Picrosirius red (PR) was used to assess fibrosis. Digital images were used to count MC/mm(2) using ImageJ software. Western blot (WB) for MC-tryptase in 12 GCMN and 12 non-nevus samples was performed. Analysis of variance (Tukey) and Pearson statistical tests were applied. Increased MCs were observed in nevus tissue (75.1 ± 35.3 MCs/mm(2)) and in uninvolved skin (53.74 ± 27.7 MC/ mm(2)). P  =  0.109 from patients with L/GCMN, compared with controls from individuals without L/GCMN (28.74 ± 8.4 MC/mm(2)); P  =  0.001 supported by results of WB analysis for tryptase. A positive trend toward correlation of MC numbers with fibrosis, assessed by PR staining fell short of statistical significance (r  =  0.245; P  =  0.086); no difference in fibrosis was found between nevus and non-nevus skin from patients with L/GCMN (P  =  0.136). We found a higher density of MC, both in normal-appearing skin and nevus areas of L/GCMN patients, compared with control skin samples from individuals without nevi. Given the abnormal wound healing and allergic reactions described in L/GCMN patients, these findings suggest a potential role for MC in the biology of L/GCMN, making them a potential target for therapeutic intervention.

Immunohistochemical and ultrastructural features of congenital melanocytic naevus cells support a stem-cell phenotype

Background Multiple congenital melanocytic naevi (CMN) in one individual are caused by somatic mosaicism for NRAS mutations; however, the lineage of the mutated cells remains uncertain.

Objectives To test the hypothesis that CMN may be derived from cutaneous stem cells.

Methods Sixty-six CMN samples from 44 patients were stained for immunohistochemical (IHC) markers of melanocytic differentiation (TYR, TRP1, TRP2, LEF1, MITF, cKit), pluripotency (nestin, fascin, CD133, CD20, CD34), monocyte/macrophage lineage (CD68, CD163, CD14), proliferation (Ki67) and MTOR/Wnt-signalling pathway activation (pS6, β-catenin). Semiquantitative scoring compared samples with naevus cell nesting (group 1) with those with only diffuse dermal infiltration (group 2). Transmission electron microscopy (TEM) was performed on 10 samples.

Results A normal melanocyte population was seen overlying many dermal CMN. Group 1 samples were significantly more likely to express melanocytic differentiation markers than group 2, and expression decreased significantly with depth. Expression of these markers was correlated with each other, and with nestin and fascin. CD20 staining was positive in a substantial proportion and was stronger superficially. Expression of β-catenin and pS6 was almost universal. Some samples expressed monocyte/macrophage markers. TEM revealed variable naevus cell morphology, striking macromelanosomes, double cilia and microvilli.

Conclusions Congenital melanocytic naevi development frequently coexists with normal overlying melanocyte development, leading us to hypothesize that in these cases CMN are likely to develop from a cell present in the skin independent of, or remaining after, normal melanocytic migration. IHC and TEM findings are compatible with CMN cells being of cutaneous stem-cell origin, capable of some degree of melanocytic differentiation superficially.

Pigmented lesions of the oral cavity: an update

Oral pigmentation may be focal, multifocal, or diffuse. The lesions may be blue, purple, brown, gray, or black. They may be macular or tumefactive. Some are localized harmless accumulations of melanin, hemosiderin, or exogenous metal; others are harbingers of systemic or genetic disease; and some can be associated with life-threatening medical conditions that require immediate intervention. The differential diagnosis for any pigmented lesion is extensive, and can include examples of endogenous and exogenous pigmentation. Although biopsy is a helpful and necessary aid in the diagnosis of focally pigmented lesions, with diffuse presentations lesions require a thorough history and laboratory studies to establish a definitive diagnosis.

Congenital melanocytic nevi: where are we now? Part I. Clinical presentation, epidemiology, pathogenesis, histology, malignant transformation, and neurocutaneous melanosis

Congenital melanocytic nevi (CMN) are present at birth or arise during the first few weeks of life. They are quite common, may have a heritable component, and can present with marked differences in size, shape, color, and location. Histologic and dermatoscopic findings may help suggest the diagnosis, but they are not entirely specific. CMN are categorized based on size, and larger lesions can have a significant psychosocial impact and other complications. They are associated with a variety of dermatologic lesions, ranging from benign to malignant. The risk of malignant transformation varies, with larger CMN carrying a significantly higher risk of malignant melanoma (MM), although with an absolute risk that is lower than is commonly believed. They may also be associated with neuromelanosis, which may be of greater concern than cutaneous MM. The information presented herein aims to help dermatologists determine when it is prudent to obtain a biopsy specimen or excise these lesions, to obtain radiographic imaging, and to involve other specialists (eg, psychiatrists and neurologists) in the patient's care.

New recommendations for the categorization of cutaneous features of congenital melanocytic nevi

BACKGROUND

The diameter of congenital melanocytic nevi (CMN) has served as the lone criterion for determining risks of adverse outcomes such as melanoma. A standardized description of additional morphologic features is needed.

OBJECTIVE

We sought to develop a consensus-based standardized categorization of cutaneous features of CMN and to test agreement among experts on the proposed scheme.

METHODS

An interdisciplinary group of experts in the field of CMN was surveyed using a detailed questionnaire. Applicability of the expert consensus-based scheme was tested for interobserver agreement.

RESULTS

The principal variable of the consensus-based categorization is CMN size, based on maximal diameter the CMN is projected to attain by adulthood. CMN size categories include: small (<1.5 cm); medium (M1: 1.5-10 cm, M2: >10-20 cm); large (L1: >20-30 cm, L2: >30-40 cm); and giant (G1: >40-60 cm, G2: >60 cm). In addition, number of satellite nevi in the first year of life is categorized into none, 1 to 20, more than 20 to 50, and more than 50 satellites. Additional descriptors of CMN include anatomic localization, color heterogeneity, surface rugousity and presence of hypertrichosis (described as none, moderate, marked), and presence of dermal or subcutaneous nodules (none, scattered, extensive). Assessment of consistency among 3 experts showed moderate to excellent interobserver agreement for categorization of the clinical descriptors (kappa values 0.54-0.93).

LIMITATIONS

Applicability of the proposed scheme was tested in a virtual setting and only among experts.

CONCLUSION

The proposed categorization scheme for CMN was agreed upon by experts and showed good interobserver agreement. Such standardized reporting of patients with CMN facilitates the development of an international clinical database for the study of large and giant CMN.

On the development of neurocutaneous units--implications for the histogenesis of congenital, acquired, and dysplastic nevi

This study of spontaneous abortions and fetal deaths in utero used immunostains to evaluate the structure of developing cutaneous nerves. Melan-A immunostains were also used to screen 25 cases of grossly normal fetal skin for occult fetal nevi. Discrete portions of epidermis were generally supplied by branches emanating from regularly spaced deep cutaneous nerves, producing a wedge shape, interpreted as neurocutaneous units (NCU). Deeper nerves embraced broader portions of epidermis. Some nerves ran parallel to epidermis, especially near the superficial vascular plexus at the junction of superficial and deep dermis. Nerve sheath stem cells in each NCU may supply the melanocytes needed by the corresponding portion of epidermis. Transformed nerve sheath stem cells may lead to formation of occult prenatal nevi, whose histology and histogenesis may best be understood in terms of NCUs. In particular, the size and shape of a nevus may be largely determined by its NCU of origin. Six fetal nevi were detected, and 3 occult lumbosacral Mongolian spots; all in deep dermis, no later than the middle of the second trimester, mainly with a pattern of singly dispersed deep dermal melanocytes. These findings suggest that congenital (prenatal) nevi begin as intradermal nevi. In addition to explaining congenital nevi, these findings have implications for the histogenesis of acquired (postnatal) nevi and dysplastic nevi.

[New aspects of congenital melanocytic nevi]

In recent years, prospective studies with increasing patient numbers have been published on the subject of congenital melanocytic nevi (CMN) and neurocutaneous melanocytosis (NCM). Moreover, medical experts and patient support groups have intensified their collaboration. This article summarizes current aspects of pathogenesis, clinical features, and therapy of CMN and NCM.

Four cases of lobulated intradermal nevus: a sign of aging melanocytic nevus

Melanocytic nevi are subject to change with age in both clinical and histopathologic findings. In 1991, Cho et al. first reported three cases of lobulated intradermal nevi and suggested their cases represented an unusual form of regressing melanocytic nevus. Herein we report four cases of lobulated intradermal nevus and review previous literature.

Estrogen receptor beta expression in nevi during pregnancy

Estrogen levels increase during pregnancy and clinical evidence has long suggested that melanocytes are estrogen-responsive. We hypothesized that nevi from pregnant patients would exhibit increased expression of estrogen receptor beta (ERbeta) and thus enhanced potential to respond to altered estrogen levels. Normal, dysplastic and congenital nevi (n = 212) were collected from pregnant and non-pregnant women ranging from 18 to 45 years of age. Immunohistochemical staining was performed on these nevi using antibodies specifically directed against estrogen receptor alpha (ERalpha) and ERbeta. ERalpha was not observed in any lesions; thus, ERbeta was the predominant estrogen receptor in melanocytic cells from all types of nevi. Enhanced positivity for ERbeta in normal nevi during pregnancy was noted, compared with non-pregnant controls including nevocytes residing in both the epidermal and dermal micro-environments (P = 0.005 and P = 0.001 respectively). Nevi with increasingly melanocytic atypia showed increased ERbeta in nevocytes nested within the epidermis. No additional increase in ERbeta in atypical nevi was observed during pregnancy. For normal and congenital nevi, regardless of pregnancy status, dermally associated nevocytes tended to have greater ERbeta immunoreactivity. Significant decreases in ERbeta immunoreactivity were observed in congenital nevi from pregnant women compared with normal and dysplastic nevi from pregnant women. Our data suggest that nevi possess the capacity to be estrogen-responsive. Factors such as pregnancy and degree of atypia are associated with enhanced ERbeta with the exception of congenital nevi where the melanocytes were unique in their response to pregnancy.