Genomic analysis of blue nevi and related dermal melanocytic proliferations

Ancillary testing for melanoma: current trends and practical considerations

The diagnosis of melanocytic lesions is aided by ancillary testing, but clinical inspection with the histomorphological assessment on biopsy remains sufficient in most cases. Immunohistochemistry and molecular studies have proven useful for diminishing the pool of histomorphologically borderline lesions, and sequential testing may further improve overall diagnostic performance, but these assays should be used in a stepwise fashion if at all. Ancillary tests vary based on their technology, performance, and practical considerations, including but not limited to the specific diagnostic question, cost, and turn-around time, which impact test selection. This review examines currently used ancillary tests for the purpose of characterizing melanocytic lesions. Both scientific and practical considerations are discussed.

Molecular testing in melanoma for the surgical pathologist

The diagnostic work-up of melanocytic tumours has undergone significant changes in the last years following the exponential growth of molecular assays. For the practising pathologist it is often difficult to sort through the multitude of different tests that are currently available for clinical use. The molecular tests used in melanocytic pathology can be broadly divided into four categories: (1) tests that predict response to systemic therapy in melanoma; (2) tests that predict prognosis in melanoma; (3) tests useful in determining the type or class of melanocytic tumour; and (4) tests useful in the differential diagnosis of naevus versus melanoma (primarily used as an aid in the diagnosis of histologically ambiguous melanocytic lesions). This review will present an updated synopsis of major molecular ancillary tests used in clinical practice.

Genome-wide copy number variations as molecular diagnostic tool for cutaneous intermediate melanocytic lesions: a systematic review and individual patient data meta-analysis

Cutaneous intermediate melanocytic neoplasms with ambiguous histopathological features are diagnostically challenging. Ancillary cytogenetic techniques to detect genome-wide copy number variations (CNVs) might provide a valuable tool to allow accurate classification as benign (nevus) or malignant (melanoma). However, the CNV cut-off value to distinguish intermediate lesions from melanoma is not well defined. We performed a systematic review and individual patient data meta-analysis to evaluate the use of CNVs to classify intermediate melanocytic lesions. A total of 31 studies and 431 individual lesions were included. The CNV number in intermediate lesions (median 1, interquartile range [IQR] 0-2) was significantly higher (p<0.001) compared to that in benign lesions (median 0, IQR 0-1) and lower (p<0.001) compared to that in malignant lesions (median 6, IQR 4-11). The CNV number displayed excellent ability to differentiate between intermediate and malignant lesions (0.90, 95% CI 0.86-0.94, p<0.001). Two CNV cut-off points demonstrated a sensitivity and specificity higher than 80%. A cut-off of ≥3 CNVs corresponded to 85% sensitivity and 84% specificity, and a cut-off of ≥4 CNVs corresponded to 81% sensitivity and 91% specificity, respectively. This individual patient data meta-analysis provides a comprehensive overview of CNVs in cutaneous intermediate melanocytic lesions, based on the largest pooled cohort of ambiguous melanocytic neoplasms to date. Our meta-analysis suggests that a cut-off of ≥3 CNVs might represent the optimal trade-off between sensitivity and specificity in clinical practice to differentiate intermediate lesions from melanoma.

Primary Cilia Are Preserved in Cellular Blue and Atypical Blue Nevi and Lost in Blue Nevus-like Melanoma

Distinguishing cellular blue nevi (CBNs) and atypical CBNs from blue nevus-like melanoma (BNLM) can be diagnostically challenging. Immunohistochemistry may inform the diagnosis in a subset of cases but is not always diagnostic. Further, ancillary molecular testing is expensive and often requires significant tissue to complete. Primary cilia are cell-surface organelles with roles in signal transduction pathways and have been shown to be preserved in conventional melanocytic nevi but lost in melanoma. Immunofluorescence staining of primary cilia can be performed using a single standard-thickness formalin-fixed paraffin-embedded tissue section and has a turnaround time similar to immunohistochemistry. The percentage of tumoral melanocytes retaining a primary cilium is quantified and reported as the ciliation index. In the current study, we explored the utility of the ciliation index in a series of 31 blue nevus-like lesions, including CBNs (12), atypical CBNs (15), and BNLM (4). The average ciliation index for the CBNs was 59±18%, with a median of 60 (range: 28 to 87). The average ciliation index for atypical CBNs was 59±23, with a median of 59 (range: 20 to 93). The average ciliation index for BNLM was 4±3, with a median of 3 (range: 1 to 8). There was no significant difference in ciliation index between the CBN and atypical CBN categories. There was a significant difference between CBN and BNLM and between atypical CBNs and BNLM (P<0.001 for each). Here, we show that ciliation index is a quantitative diagnostic tool useful in the setting of blue nevus-like neoplasms, with benefits including cost and time efficiency.

Melanocytic lesions with blue naevus-like (dendritic) morphology: an update with an emphasis on histopathological, immunophenotypic, and molecular features

An accurate diagnosis of melanocytic lesions requires a thorough histopathological evaluation accompanied by appropriate correlation with clinical examination findings. Although most melanocytic lesions can readily be classified as one of the defined diagnostic entities according to well-established diagnostic criteria, a subset of melanocytic lesions, particularly those with blue naevus-like (pigmented dendritic) morphology, have notoriously constituted an enduring challenge for pathologists. These lesions are rare and often show histological ambiguities, with features of both benignity and malignancy, thereby making accurate risk assessment and prediction of their biological behaviours difficult on histological grounds alone. Herein, we outline a practical and systematic approach for the diagnosis of melanocytic lesions with dendritic morphology, with a particular focus on histological and immunophenotypic features that help to distinguish one entity from another. In this review, we provide the most current knowledge on these melanocytic lesions in the literature and our experience with these rare entities, and we discuss the utility of molecular techniques as an ancillary tool, especially in histologically ambiguous and/or borderline lesions.

Histopathologic classification and prognostic factors of melanoma: a 2021 update

Despite the rapid recent advances in molecular analysis of tumors, which allow large-scale and high-resolution genomics, the "gold standard" for melanoma diagnosis continues to be histopathology, in conjunction with clinical characteristics and sometimes with important support of immunohistochemistry. Observations, where postulated that cutaneous melanomas may arise through two distinct pathways, discoveries such as that BRAF^V600E mutations were mostly common in melanomas on sun-exposed skin with little solar elastosis and seminal works for melanoma progression and evolution set the groundwork for the new WHO Classification of Melanoma: a classification of melanoma that not only encompasses histologic but also clinical, epidemiologic, and genetic characteristics. The melanomas were divided into those etiologically related to sun exposure and those that are not, based on their mutational signatures, anatomic site, and epidemiology. On the basis of degree of associated solar elastosis melanomas on the sun exposed skin were further divided by the histopathologic degree of cumulative solar damage (CSD) of the surrounding skin, into low and high CSD. On the low-CSD group of melanomas are included superficial spreading melanomas, while the high-CSD melanomas encompasses lentigo maligna and desmoplastic melanomas. The "non-CSD" classification includes acral melanomas, some melanomas in congenital nevi, melanomas in blue nevi, Spitz melanomas, mucosal melanomas, and uveal melanomas. Nodular and nevoid melanoma may occur in any pathway. A group of intermediate tumors termed melanocytoma is proposed for tumors that in addition to mutations that activate the MAPK pathway, harbor multiple driver mutations, and they are either low-grade or high-grade, to indicate that they may carry a higher risk of malignant transformation. In this review a summary of the most recent WHO classification of melanoma is provided. A short analysis of essential histopathologic prognostic parameters is also provided. The new classification of melanoma discriminates distinct types of melanoma based on their clinicopathologic, and genomic characteristics. Undoubtedly, melanoma research will continue to evolve as new clinical, pathological, molecular data accumulates. The challenge of the forthcoming years is to better characterize the intermediate category of melanocytic lesions.

BAP-1 Expression Status by Immunohistochemistry in Cellular Blue Nevus and Blue Nevus-like Melanoma

The family of blue nevi includes the common blue nevus (BN), cellular blue nevus (CBN), and atypical BN, while melanomas with BN-like morphology can either arise in association with a blue nevus (MABN) or in the de novo setting mimicking cellular blue nevus (MMCBN). Recent molecular and immunohistochemical studies have demonstrated loss of BAP-1 in MABN/MMCBN but not in BN/CBN, suggesting that loss of BAP-1 correlates with a malignant phenotype in these lesions. In this study, we applied anti-BAP-1 antibodies to a series of CBN/BN (n = 11) and MABN/MMCBN (n = 4). Nuclear BAP-1 expression was detected in the majority of CBN/BN (n = 10/11) but was lost in 1 case. Most cases of MABN/MMCBN showed loss of nuclear BAP-1 expression (n = 3/4), with one case of MMCBN showing preserved BAP-1 expression. Demonstration of BAP-1 loss in a single case of CBN and preservation of BAP-1 expression in 1 case of MMCBN may indicate that detection of alterations in BAP-1 protein expression by immunohistochemistry may not be a completely reliable biomarker for the distinction of BN/CBN from MABN/MMCBN. Further investigation of the significance of BAP-1 loss/preservation in BN-like tumors is warranted.

Through the looking glass and what you find there: making sense of comparative genomic hybridization and fluorescence in situ hybridization for melanoma diagnosis

Melanoma is the leading cause of death among cutaneous neoplasms. Best outcome relies on early detection and accurate pathologic diagnosis. For the great majority of melanocytic tumors, histopathologic examination can reliably distinguish nevi from melanomas. However, there is a subset of melanocytic tumors that cannot be definitively classified as benign or malignant using histopathological criteria alone. These tumors are usually diagnosed using terms that imply various degrees of uncertainty in regards to their malignant potential and create the possibility for over or undertreatment. For such tumors, additional ancillary tests would be beneficial in adjudicating a more definitive diagnosis. In recent years, DNA-based molecular ancillary tests, specifically comparative genomic hybridization and fluorescence in situ hybridization, have been developed to help guide the diagnosis of ambiguous melanocytic proliferations. This study will present an updated overview of these two major ancillary tests, which are currently being used in clinical practice to assist in the diagnosis of challenging melanocytic neoplasms.

The 2018 World Health Organization Classification of Cutaneous, Mucosal, and Uveal Melanoma: Detailed Analysis of 9 Distinct Subtypes Defined by Their Evolutionary Pathway

CONTEXT.—

There have been major advances in the understanding of melanoma since the last revision of the World Health Organization (WHO) classification in 2006.

OBJECTIVE.—

To discuss development of the 9 distinct types of melanoma and distinguishing them by their epidemiology, clinical and histologic morphology, and genomic characteristics. Each melanoma subtype is placed at the end of an evolutionary pathway that is rooted in its respective precursor, wherever appropriate and feasible, based on currently known data. Each precursor has a variable risk of progression culminating in its fully evolved, invasive melanoma.

DATA SOURCES.—

This review is based on the "Melanocytic Tumours" section of the 4th edition of the WHO Classification of Skin Tumours, published in 2018.

CONCLUSIONS.—

Melanomas were divided into those etiologically related to sun exposure and those that are not, as determined by their mutational signatures, anatomic site, and epidemiology. Melanomas on the sun-exposed skin were further divided by the histopathologic degree of cumulative solar damage (CSD) of the surrounding skin, into low and high CSD, on the basis of degree of associated solar elastosis. Low-CSD melanomas include superficial spreading melanomas and high-CSD melanomas incorporate lentigo maligna and desmoplastic melanomas. The "nonsolar" category includes acral melanomas, some melanomas in congenital nevi, melanomas in blue nevi, Spitz melanomas, mucosal melanomas, and uveal melanomas. The general term melanocytoma is proposed to encompass "intermediate" tumors that have an increased (though still low) probability of disease progression to melanoma.

ALK Rearrangements Are Infrequent in Cellular Blue Nevus and Deep Penetrating Nevus

Recent studies have identified kinase fusions in Spitzoid melanocytic neoplasms, and approximately 10% of Spitzoid neoplasms harbor anaplastic lymphoma kinase (ALK) rearrangements and corresponding ALK immunoreactivity. Deep penetrating nevi (DPN), a subset of melanocytic neoplasms, have histologic and immunohistochemical overlap that have historically supported classification of DPN with blue/cellular blue nevi (CBN). However, HRAS mutations have rarely been detected in DPN, thereby also linking them to Spitz nevi. The purpose of this study was to see if DPN or CBN possess ALK rearrangements, thereby providing more evidence that these melanocytic lesions may be pathogenetically related to Spitzoid neoplasms. Using ALK immunohistochemistry as a surrogate for ALK rearrangement, the authors examined 26 DPN, 30 CBN, and 4 conventional blue nevi. ALK immunoreactive cases underwent fluorescent in situ hybridization to investigate for the presence of ALK gene rearrangement. Patchy and focal ALK immunostaining was found in only 1 case of DPN (1/26, 3.8%). Seven cases of CBN (7/30; 23%) showed ALK immunostaining (6 focal/patchy, 1 strong and diffuse). Fluorescent in situ hybridization using ALK break-apart probes showed various degrees of gain of 2p23 and rare ALK break-apart signals. Four CBN showed ALK rearrangement in 2%-4% of cells. Two cases of CBN showed gain of 2p23 in 10%-20% of cells. In our study, ALK rearrangements are uncommon in both CBN and DPN, making ALK an unlikely driver in tumorigenesis and classification of these melanocytic variants. However, our study did identify ALK molecular changes and immunohistochemical staining patterns that have not been previously described in CBN or DPN.

Blue nevus and "malignant blue nevus:" A concise review

Blue nevi are a heterogeneous group of lesions that can display a variety of different clinicopathological characteristics. Although attempts are made to classify each lesion into defined subtypes, there can be overlap between the subtypes. The clinical and histolopathologic features of common blue nevi and cellular blue nevi are discussed, as well as blue nevi with atypical features and malignant lesions with features of blue nevi.

Genomic copy number analysis of a spectrum of blue nevi identifies recurrent aberrations of entire chromosomal arms in melanoma ex blue nevus

Blue nevi may display significant atypia or undergo malignant transformation. Morphologic diagnosis of this spectrum of lesions is notoriously difficult, and molecular tools are increasingly used to improve diagnostic accuracy. We studied copy number aberrations in a cohort of cellular blue nevi, atypical cellular blue nevi, and melanomas ex blue nevi using Affymetrix's OncoScan platform. Cases with sufficient DNA were analyzed for GNAQ, GNA11, and HRAS mutations. Copy number aberrations were detected in 0 of 5 (0%) cellular blue nevi, 3 of 12 (25%) atypical cellular blue nevi, and 6 of 9 (67%) melanomas ex blue nevi. None of the atypical cellular blue nevi displayed more than one aberration, whereas complex aberrations involving four or more regions were seen exclusively in melanomas ex blue nevi. Gains and losses of entire chromosomal arms were identified in four of five melanomas ex blue nevi with copy number aberrations. In particular, gains of 1q, 4p, 6p, and 8q, and losses of 1p and 4q were each found in at least two melanomas. Whole chromosome aberrations were also common, and represented the sole finding in one atypical cellular blue nevus. When seen in melanomas, however, whole chromosome aberrations were invariably accompanied by partial aberrations of other chromosomes. Three melanomas ex blue nevi harbored aberrations, which were absent or negligible in their precursor components, suggesting progression in tumor biology. Gene mutations involving GNAQ and GNA11 were each detected in two of eight melanomas ex blue nevi. In conclusion, copy number aberrations are more common and often complex in melanomas ex blue nevi compared with cellular and atypical cellular blue nevi. Identification of recurrent gains and losses of entire chromosomal arms in melanomas ex blue nevi suggests that development of new probes targeting these regions may improve detection and risk stratification of these lesions.

Methods of Melanoma Detection

Detection and removal of melanoma, before it has metastasized, dramatically improves prognosis and survival. The purpose of this chapter is to (1) summarize current methods of melanoma detection and (2) review state-of-the-art detection methods and technologies that have the potential to reduce melanoma mortality. Current strategies for the detection of melanoma range from population-based educational campaigns and screening to the use of algorithm-driven imaging technologies and performance of assays that identify markers of transformation. This chapter will begin by describing state-of-the-art methods for educating and increasing awareness of at-risk individuals and for performing comprehensive screening examinations. Standard and advanced photographic methods designed to improve reliability and reproducibility of the clinical examination will also be reviewed. Devices that magnify and/or enhance malignant features of individual melanocytic lesions (and algorithms that are available to interpret the results obtained from these devices) will be compared and contrasted. In vivo confocal microscopy and other cellular-level in vivo technologies will be compared to traditional tissue biopsy, and the role of a noninvasive "optical biopsy" in the clinical setting will be discussed. Finally, cellular and molecular methods that have been applied to the diagnosis of melanoma, such as comparative genomic hybridization (CGH), fluorescent in situ hybridization (FISH), and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), will be discussed.

Lentigo Maligna Melanoma With Local and Distant Blue Nevus-like Metastases

Melanoma or melanoma metastases can rarely mimic blue nevi clinically and/or histologically, presenting a diagnostic pitfall for both the clinician and the dermatopathologist. We report a case of an invasive lentigo maligna melanoma with subsequent development of multiple, cutaneous blue nevus-like localized metastases followed by a distant metastasis, heralding widespread systemic metastases.

Ambiguous melanocytic tumors with loss of 3p21

Germline loss-of-function mutations in BAP1 are associated with the development of cutaneous melanocytic tumors with some histopathologic characteristics seen in Spitz nevi. Similar melanocytic tumors occurring in a sporadic setting have been demonstrated to have biallelic loss of BAP1. In some of these sporadic tumors, loss of BAP1 occurs through mutation of 1 allele and genomic loss of the other. We screened our database of comparative genomic hybridization profiles of ambiguous melanocytic tumors to identify cases with a single genomic event involving loss of the BAP1 locus. The prevalence of tumors with a single genomic event involving loss of BAP1 was 6.7% in our study population. We further characterized the BAP1 status in 17 of these tumors with available additional material, confirming loss of BAP1 in all cases. We describe BAP1 loss in a blue nevus-like melanoma and further expand the histopathologic spectrum of spitzoid melanocytic neoplasms with BAP1 loss.

Chromosomal copy number analysis in melanoma diagnostics

The majority of melanocytic neoplasms can be correctly diagnosed using routine histopathologic analysis. However, a significant minority of tumors have ambiguous histopathologic attributes that overlap between melanocytic nevi and melanoma. Ancillary tests that assist in distinguishing potentially lethal melanomas from benign melanocytic nevi with atypical histopathologic features are available, but still need refining.Most melanomas have chromosomal copy number aberrations, frequently involving multiple chromosomes. With rare exceptions, such anomalies are not found in melanocytic nevi. This difference formed the basis to develop assays that can help distinguish melanoma from nevi by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). FISH can detect chromosomal copy number changes of a limited number of loci within individual cells. By contrast, CGH assesses copy number across the entire genome, but typically is performed on bulk cell populations so that copy number changes in individual cells or subpopulations of cells can go undetected. Both FISH and CGH have been used to provide genomic information in histopathologically ambiguous melanocytic tumors that can assist pathologists make correct diagnoses.

The molecular pathology of melanoma: an integrated taxonomy of melanocytic neoplasia

Melanomas comprise multiple biologically distinct categories, which differ in cell of origin, age of onset, clinical and histologic presentation, pattern of metastasis, ethnic distribution, causative role of UV radiation, predisposing germ-line alterations, mutational processes, and patterns of somatic mutations. Neoplasms are initiated by gain-of-function mutations in one of several primary oncogenes, which typically lead to benign melanocytic nevi with characteristic histologic features. The progression of nevi is restrained by multiple tumor-suppressive mechanisms. Secondary genetic alterations override these barriers and promote intermediate or overtly malignant tumors along distinct progression trajectories. The current knowledge about the pathogenesis and clinical, histologic, and genetic features of primary melanocytic neoplasms is reviewed and integrated into a taxonomic framework.

Identification of HRAS mutations and absence of GNAQ or GNA11 mutations in deep penetrating nevi

HRAS is mutated in ∼15% of Spitz nevi, and GNAQ or GNA11 is mutated in blue nevi (46-83% and ∼7% respectively). Epithelioid blue nevi and deep penetrating nevi show features of both blue nevi (intradermal location, pigmentation) and Spitz nevi (epithelioid morphology). Epithelioid blue nevi and deep penetrating nevi can also show overlapping features with melanoma, posing a diagnostic challenge. Although epithelioid blue nevi are considered blue nevic variants, no GNAQ or GNA11 mutations have been reported. Classification of deep penetrating nevi as blue nevic variants has also been proposed, however, no GNAQ or GNA11 mutations have been reported and none have been tested for HRAS mutations. To better characterize these tumors, we performed mutational analysis for GNAQ, GNA11, and HRAS, with blue nevi and Spitz nevi as controls. Within deep penetrating nevi, none demonstrated GNAQ or GNA11 mutations (0/38). However, 6% revealed HRAS mutation (2/32). Twenty percent of epithelioid blue nevi contained a GNAQ mutation (2/10), while none displayed GNA11 or HRAS mutation. Eighty-seven percent of blue nevi contained a GNAQ mutation (26/30), 4% a GNA11 mutation (1/28), and none an HRAS mutation. Within Spitz nevi, none demonstrated GNAQ or GNA11 mutations (0/30). Seventeen percent contained an HRAS mutation (5/30). All GNAQ and GNA11 mutations were p.Q209L (c.626A>T) point mutations, except 2 GNAQ mutations, which contained novel c.625_626CA>TT double mutations. Four HRAS mutations were in exon 2, and three in exon 3. This is the first study to identify HRAS mutations in deep penetrating nevi. The presence of HRAS mutations and absence of GNAQ or GNA11 mutations in deep penetrating nevi suggests classification of these unusual nevi within the Spitz nevus category of melanocytic tumors, rather than the blue nevus category.

Proliferative activity, chromosomal aberrations, and tumor-specific mutations in the differential diagnosis between blue nevi and melanoma

Blue nevi are a clinically and pathologically heterogeneous group of benign pigmented dermal melanocytic tumors that may exhibit histologic overlap with malignant melanoma. This study evaluates the role of immunohistochemical and molecular analyses in the classification and differential diagnosis between blue nevi and melanoma. Twenty-three dermal melanocytic tumors, initially diagnosed as benign or ambiguous, were subjected to immunohistochemical staining for phosphohistone H3 and MIB-1 to evaluate mitotic activity, comparative genomic hybridization to detect chromosomal aberrations, and GNAQ, GNA11, BRAF, NRAS, and KRAS sequencing. Of 19 patients with follow-up information (median, 1.6 years), 3 developed recurrent or metastatic disease. Nevertheless, 11 of the 19 patients with follow-up had <2 years of follow-up. Nine of 23 patients showed chromosomal aberrations, including all 3 patients with tumor recurrence or progression. There was no significant correlation between mutation status (P = 0.6) or mitotic rate (P = 0.3) and outcome. In conclusion, three of nine patients with chromosomal aberrations developed tumor recurrence or progression. Patients with histologically ambiguous dermal melanocytic proliferations that exhibit copy number aberrations should undergo careful clinical follow-up.

Melanoma arising in a large plaque-type blue nevus with subcutaneous cellular nodules

Melanoma may arise in association with and/or simulate the appearance of a cellular blue nevus. The distinction of a cellular blue nevus with atypical features from blue nevus-like melanoma can be difficult. One rare setting, in which one may face this diagnostic challenge, is nodule formation in a large plaque-type blue nevus. We have previously reported 2 patients with cellular blue nevus-like subcutaneous nodules without overt malignant features and indolent clinical behavior. Herein we report a patient who developed malignant melanoma in association with a large plaque-type blue nevus. A 46-year-old woman with a history of "cellular blue nevus" of the breast that developed 7 years earlier during pregnancy had soft tissue nodules at the prior surgical site. She was found to have melanoma associated with a large plaque-type blue nevus, which involved the skin and subcutis of the chest wall and extended into breast parenchyma. Ten years after mastectomy and axillary node dissection with negative lymph nodes, the melanoma recurred as a subcutaneous chest wall nodule. Cytogenetic analysis revealed a number of aberrations, including deletion of 6q and gains of 6p and 8q. The patient then developed visceral metastases, first to the liver, and died of widely metastatic melanoma. In contrast, the cytogenetic findings of a previously reported cellular blue nevus-like nodule in a patient with a large plaque-type blue nevus were normal. That patient is still alive with no evidence of melanoma 16 years after the surgical excision of the subcutaneous cellular blue nevus-like nodule.

Skin lesions in hereditary endocrine tumor syndromes

OBJECTIVE

To review the main cutaneous manifestations of hereditary endocrine tumor syndromes and discuss currently known molecular mechanisms involved in their pathogenesis.

METHODS

On the basis of our collective experience and a comprehensive MEDLINE literature search of the English-language literature published between January 1957 and September 2010 using the search terms "skin," "cutaneous," "multiple endocrine neoplasia," "Carney complex," and "McCune-Albright syndrome," we reviewed the dermatologic findings in multiple endocrine neoplasia type 1 and type 2, Carney complex, and McCune-Albright syndrome.

RESULTS

Although the category of hereditary endocrine tumor syndromes consists of a broad spectrum of conditions, only the aforementioned few are prominently associated with cutaneous features. Because the cutaneous findings associated with these diseases are generally benign, they are often ignored or dismissed as ancillary findings in the context of severe systemic involvement. Accordingly, the pertinent literature is relatively scarce and often fails to provide a comprehensive insight about this issue. Nevertheless, timely recognition of such dermatologic manifestations may have a critical role in the early diagnosis and appropriate management of the related syndromes. Moreover, specific genotype-phenotype correlations may convey important prognostic implications.

CONCLUSION

Many physicians are unfamiliar with the cutaneous findings in the hereditary endocrine tumor syndromes described in this review. Nonetheless, knowledge of their existence can have a major role in establishing an early diagnosis of these syndromes and determining the patient's prognosis.

Extensive intraoral blue nevus--case report

Nevus is a congenital pigmented malformation rarely found in the oral mucosa. Around one third of cases located in this anatomical region are of the blue type, a histological variant with considerable tendency to malignancy. This study reports the case of a male patient, chronic smoker, with a blue nevus measuring 5 cm in diameter on the hard palate. Since controversy exists in the literature regarding the incisional biopsy of pigmented lesions with malignant or malignant potential, excision without previous biopsy of the lesion was the therapy of choice for this case. The patient was followed-up for two years with no sign of recurrence or malignant transformation.

Blue Nevi and Variants: An Update

Context.—Blue nevi are a subset of melanocytic proliferations containing cells reminiscent of the embryonal neural crest–derived dendritic melanocytic precursors. They are common specimens in a general pathology practice, but some of their rare variants may pose diagnostic difficulty. Recent molecular studies provide new insights into genetics of blue nevi.

Objective.—To critically review clinical and histologic features of blue nevi with emphasis on diagnostic problems and rare variants, as well as to provide an update on the pathogenesis of blue nevi.

Data Sources.—Published peer-reviewed literature and personal experience of the authors.

Conclusions.—Challenging areas in diagnosis of blue nevi include recognition of amelanotic, desmoplastic, atypical, and malignant variants of blue nevus. Recent data show that mutations in genes responsible for common nevi or melanomas such as BRAF, NRAS, or c-kit are rare in blue nevi. Benign and malignant blue nevi harbor frequent mutations in the Gαq class of G-protein α subunits, Gnaq and Gna11 proteins.

Molecular analysis of a case of nevus of ota showing progressive evolution to melanoma with intermediate stages resembling cellular blue nevus

Nevus of Ota is a variant of congenital nevus, which is morphologically paucicellular and resembles a common blue nevus. Although nevus of Ota is a risk factor for uveal melanoma in white people, the development of cutaneous melanoma within nevus of Ota is a very rare occurrence with only a few reported cases. We present a case of a long-standing nevus of Ota, with radiologic imaging demonstrating a large retro-orbital mass and a biopsy showing melanoma. The histopathology of the eye exenteration specimen illustrated various stages of melanocytic progression including areas resembling a nevus of Ota, blue nevus, cellular blue nevus, and melanoma. There was heterogeneity in the overtly malignant sections with some areas displaying expansile nodules of blander appearing spindled cells, whereas other areas were composed of epithelioid cells with higher mitotic counts and zones of necrosis. The extensive lesion also infiltrated the soft tissue and bone. We performed gene mutation analysis for GNAQ, BRAF, NRAS, and KIT and fluorescence in situ hybridization (FISH) targeting commonly altered chromosomal loci in melanoma and comparative genomic hybridization (CGH). Copy number changes typical of melanoma were identified by both FISH and CGH in the morphologically malignant areas illustrating the relationship of tumor progression and the progressive acquisition of genetic aberrations.

Molecular cytogenetics of cutaneous melanocytic lesions - diagnostic, prognostic and therapeutic aspects

This review intends to update current knowledge regarding molecular cytogenetics in melanocytic tumours with a focus on cutaneous melanocytic lesions. Advantages and limitations of diverse, already established methods, such as (fluorescence) in situ hybridization and mutation analysis, to detect these cytogenetic alterations in melanocytic tumours are described. In addition, the potential value of more novel techniques such as multiplex ligation-dependent probe amplification is pointed out. This review demonstrates that at present cytogenetics has mainly increased our understanding of the pathogenesis of melanocytic tumours, with an important role for activation of the mitogen-activated protein kinase (MAPK) signalling pathway in the initiation of melanocytic tumours. Mutations in BRAF (in common naevocellular naevi), NRAS (congenital naevi), HRAS (Spitz naevi) and GNAQ (blue naevi) can all cause MAPK activation. All these mutations seem early events in the development of melanocytic tumours, but by themselves are insufficient to cause progression towards melanoma. Additional molecular alterations are implicated in progression towards melanoma, with different genetic alterations in melanomas at different sites and with varying levels of sun exposure. This genetic heterogeneity in distinct types of naevi and melanomas can be used for the development of molecular tests for diagnostic purposes. However, at the moment only few molecular tests have become of diagnostic value and are performed in daily routine practice. This is caused by lack of large prospective studies on the diagnostic value of molecular tests including follow-up, and by the low prevalence of certain molecular alterations. For the future we foresee an increasing role for cytogenetics in the treatment of melanoma patients with the increasing availability of targeted therapy. Potential targets for metastatic melanoma include genes involved in the MAPK pathway, such as BRAF and RAS. More recently, KIT has emerged as a potential target in melanoma patients. These targeted treatments all need careful evaluation, but might be a promising adjunct for treatment of metastatic melanoma patients, in which other therapies have not brought important survival advantages yet.

State of the art, nomenclature, and points of consensus and controversy concerning benign melanocytic lesions: outcome of an international workshop

The following communication summarizes the proceedings of a one-day International Workshop focusing on the histology of benign melanocytic nevi. Areas of controversy identified in 6 focus sessions were the nomenclature and relationships among common nevi including nevi with halo reactions, traumatized nevi, "dysplastic" nevi, and nevi from particular anatomic sites; developmental biology and frequency of malignant transformation associated with congenital nevi; the characterization and biologic nature of atypical spitzoid neoplasms; the basic definition of particular melanocytic cellular phenotypes, and the nomenclature and biologic nature of many candidate blue nevi, combined nevi, and other controversial lesions such as deep penetrating nevus and pigmented epithelioid melanocytoma. Concentrated data collection and follow-up, molecular characterization, and future consensus Workshops may facilitate the resolution of some of these problems. The Group recommended the description of ambiguous or "borderline" lesions as tumors with indeterminate or uncertain biologic/malignant potential. The participants also advised that such lesions at a minimum should be managed by complete excision with clear surgical margins.

Pigmented lesion pathology: what you should expect from your pathologist, and what your pathologist should expect from you

The first part of this review examines the reliability of histologic diagnosis in pigmented lesions, as measured by concordance studies and medicolegal analysis. It emphasizes the role of clinicians in maximizing that reliability, by providing adequate clinical descriptions, using appropriate biopsy technique, and critically interpreting pathology reports. It identifies those entities that are especially problematic, either because they cannot be reliably recognized by the histopathologist or because their histology is a poor guide to their biologic behavior. The second part of the review is a guide to some of the more difficult and controversial pigmented lesions, including dysplastic nevus, spitzoid nevi and melanomas, cellular blue nevus, animal-type melanoma, and deep penetrating nevus.

Blue nevi and related lesions: a review highlighting atypical and newly described variants, distinguishing features and diagnostic pitfalls

Blue nevi and related entities are a heterogenous group of congenital and acquired melanocytic tumors that includes established entities such as dendritic ("common") blue nevus and cellular blue nevus, and their numerous clinical and pathologic variants, such as deep penetrating nevus. They share several clinical and morphologic features including their blue tinctorial properties, the presence of a dermal proliferation of spindle, fusiform or ovoid cells, associated melanin pigment (both within the melanocytic tumor cells and also within macrophages) and stromal sclerosis and, at least focal positivity for HMB-45 (Gp100). Some variants, such as deep penetrating nevus, often show considerable variation in nuclear size and shape, and, as a consequence, are at risk of being misdiagnosed as melanoma by those unfamiliar with their characteristic morphologic features. The so-called malignant blue nevus is a controversial term denoting melanomas arising in association with or exhibiting some morphologic similarities to blue nevus. There are also lesions that are probably related to blue nevi, such as the recently described pigmented epithelioid melanocytoma and the neurocristic hamartomas, whose nature, biologic behavior, and relationship to the better established entities remains to be clearly established. This review aims to present a brief overview of these lesions, highlighting their pathologic characteristics, distinguishing features and potential diagnostic pitfalls, with particular emphasis on recently described entities, molecular findings, controversial areas, and approaches to diagnosis.

Distinguishing epithelioid blue nevus from blue nevus-like cutaneous melanoma metastasis using fluorescence in situ hybridization

Blue nevus (BN)-like cutaneous melanoma metastasis is a well-recognized variant of melanoma metastasis. These lesions may clinically and histologically simulate benign blue nevi. The histologic changes may be indistinguishable from conventional blue nevi or epithelioid blue nevi (EBN), a benign dermal-based melanocytic neoplasm with epithelioid morphology and heavily pigmented cytoplasm. Distinguishing BN-like cutaneous melanoma metastasis from benign conventional or EBN is important for staging and treatment. We evaluated a fluorescence in situ hybridization (FISH) assay using probes targeting 6p25 (RREB1), 6q23 (MYB), 11q13 (CCND1), and centromere 6 (Cep6) with previously determined criteria, to distinguish EBN and BN-like melanoma metastasis. Ten BN-like cutaneous melanoma metastatic lesions and 10 EBN were blindly evaluated with the above mentioned FISH probes. FISH enumeration and criteria for diagnosis of melanoma was as previously described. Nine of 10 BN-like cutaneous metastatic lesions showed significant aberrations and met previously established criteria for melanoma. None of the EBN cases showed evidence of significant copy number changes or met FISH criteria for a diagnosis of melanoma. FISH is an important diagnostic adjunct for melanocytic neoplasms. In this study, we show that a FISH assay targeting 6p25, 6q23, 11q13, and centromere 6 can distinguish EBN from BN-like metastatic melanoma with high accuracy. The test and the parameters previously established can perform with high sensitivity and specificity when dealing with this differential diagnosis.

Blue Nevi and Related Tumors

Blue nevi and related lesions are characterized by the proliferation of dermal dendritic melanocytes. Although they share certain common clinical and histologic features, they encompass a spectrum of lesions ranging from benign melanocytic hamartomas and common blue nevi to borderline malignant pigmented epithelioid melanocytoma and aggressive malignant blue nevi. This article succinctly describes the common dermal dendritic proliferations and updates readers on newly classified entities and variants. The differential diagnosis of the main entities and strategies to distinguish them from their melanocytic and nonmelanocytic mimics is also presented.