Monitoring of atypical nevi is an important step in early detection of melanoma, a clinical imperative in preventing the disease progression. Current standard diagnosis is based on biopsy and histopathologic examination, a method that is invasive and highly dependent upon physician experience. In this work, we used a clinical multiphoton microscope to image in vivo and noninvasively melanocytic nevi at three different stages: common nevi without dysplastic changes, dysplastic nevi with structural and architectural atypia, and melanoma. We analyzed multiphoton microscopy (MPM) images corresponding to 15 lesions (five in each group) both qualitatively and quantitatively. For the qualitative analysis, we identified the morphologic features characteristic of each group. MPM images corresponding to dysplastic nevi and melanoma were compared with standard histopathology to determine correlations between tissue constituents and morphology and to evaluate whether standard histopathology criteria can be identified in the MPM images. Prominent qualitative correlations included the morphology of epidermal keratinocytes, the appearance of nests of nevus cells surrounded by collagen fibers, and the structure of the epidermal-dermal junction. For the quantitative analysis, we defined a numerical multiphoton melanoma index (MMI) based on three-dimensional in vivo image analysis that scores signals derived from two-photon excited fluorescence, second harmonic generation, and melanocyte morphology features on a continuous 9-point scale. Indices corresponding to common nevi (0-1), dysplastic nevi (1-4), and melanoma (5-8) were significantly different (P < 0.05), suggesting the potential of the method to distinguish between melanocytic nevi in vivo.

Monitoring of atypical nevi is an important step in early detection of melanoma, a clinical imperative in preventing the disease progression. Current standard diagnosis is based on biopsy and histopathologic examination, a method that is invasive and highly dependent upon physician experience. In this work, we used a clinical multiphoton microscope to image in vivo and noninvasively melanocytic nevi at three different stages: common nevi without dysplastic changes, dysplastic nevi with structural and architectural atypia, and melanoma. We analyzed multiphoton microscopy (MPM) images corresponding to 15 lesions (five in each group) both qualitatively and quantitatively. For the qualitative analysis, we identified the morphologic features characteristic of each group. MPM images corresponding to dysplastic nevi and melanoma were compared with standard histopathology to determine correlations between tissue constituents and morphology and to evaluate whether standard histopathology criteria can be identified in the MPM images. Prominent qualitative correlations included the morphology of epidermal keratinocytes, the appearance of nests of nevus cells surrounded by collagen fibers, and the structure of the epidermal-dermal junction. For the quantitative analysis, we defined a numerical multiphoton melanoma index (MMI) based on three-dimensional in vivo image analysis that scores signals derived from two-photon excited fluorescence, second harmonic generation, and melanocyte morphology features on a continuous 9-point scale. Indices corresponding to common nevi (0-1), dysplastic nevi (1-4), and melanoma (5-8) were significantly different (P < 0.05), suggesting the potential of the method to distinguish between melanocytic nevi in vivo.

Agminated melanocytic nevus is an uncommon type of mole, characterized by a local group of macular or papular pigmented lesions, well demarcated, without a common pigmented background. This pattern has also been associated with Spitz nevi, dysplastic melanocytic nevi, and non-melanocytic lesions.We describe the onset of an acquired agminated melanocytic nevus after dabrafenib treatment. Our case highlights paradoxical MAPK activation in the setting of single-agent BRAF blockade and underscores the importance of characterizing the diverse side effects of selective BRAF inhibitors. This is the first case, to our knowledge, of agminated melanocytic nevus in association with dabrafenib.

Telomerase reverse transcriptase (TERT) promoter mutations (TPMs) are frequently found in different cancer types, including ∼70% of sun-exposed skin melanomas. In melanoma, TPMs are among the earliest mutations and can be present during the transition from nevus to melanoma. However, the specific factors that contribute to the selection of TPMs in certain nevi subsets are not well understood. To investigate this, we analyzed a group of dysplastic nevi (DN) by sequencing genes commonly mutated in melanocytic neoplasms. We examined the relationship between the identified mutations, patient age, telomere length, histological features, and the expression of p16. Our findings reveal that TPMs are more prevalent in DN from older patients and are associated with shorter telomeres. Importantly, these TPMs were not found in nevi with BRAF V600E mutations. Conversely, DN with BRAF V600E mutations were observed in younger patients, had longer telomeres and a higher proportion of p16-positive cells. This suggests that these nevi arrest growth independently of telomere shortening through a mechanism known as oncogene-induced senescence (OIS). These characteristics extend to melanoma-sequencing datasets, where melanomas with BRAF V600E mutations were more likely to have a CDKN2A inactivation, overriding OIS. In contrast, melanomas without BRAF V600E mutations showed a higher frequency of TPMs. Our data imply that TPMs are selected to bypass replicative senescence (RS) in cells that were not arrested by OIS. Overall, our results indicate that a subset of melanocytic neoplasms face constraints from RS, while others encounter OIS and RS. The order in which these barriers are overcome during progression to melanoma depends on the mutational context.

In vivo imaging of pigmented lesions in human skin was performed with a clinical multiphoton microscopy (MPM)- based tomograph (MPTflex, JenLab, Germany). Two-photon excited fluorescence was used for visualizing endogenous fluorophores such as NADH/FAD, keratin, melanin in the epidermal cells and elastin fibers in the dermis. Collagen fibers were imaged by second harmonic generation. Our study involved in vivo imaging of benign melanocytic nevi, atypical nevi and melanoma. The goal of this preliminary study was to identify in vivo the characteristic features and their frequency in pigmented lesions at different stages (benign, atypical and malignant) and to evaluate the ability of in vivo MPM to distinguish atypical nevi from melanoma. Comparison with histopathology was performed for the biopsied lesions. Benign melanocytic nevi were characterized by the presence of nevus cell nests at the epidermal-dermal junction. In atypical nevi, features such as lentiginous hyperplasia, acanthosis and architectural disorder were imaged. Cytological atypia was present in all the melanoma lesions imaged, showing the strongest correlation with malignancy. The MPM images demonstrated very good correlation with corresponding histological images, suggesting that MPM could be a promising tool for in vivo non-invasive pigmented lesion diagnosis, particularly distinguishing atypical nevi from melanoma. © 2013 SPIE.

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.

Neurofibromatosis type 1 ( NF1 ) is commonly mutated in melanoma, yet the risk of melanoma in individuals with NF1 is incompletely understood. We performed a systematic review to investigate the risk and characteristics of melanoma and melanocytic nevi in NF1 individuals. PubMed was searched for articles describing NF1 individuals with melanoma, or melanocytic nevi. Those with cutaneous and ocular melanomas were compared to the general population using Surveillance, Epidemiology, and End Results data. Fifty-three articles describing 188 NF1 patients were included (melanoma n  = 82, melanocytic nevi n  = 93, melanocytic nevi, and melanoma n  = 13). Compared to the general population, NF1 patients with cutaneous melanomas had earlier melanoma diagnoses (49.1 vs. 58.6 years, P = 0.012), thicker tumors (3.7 vs. 1.2 mm, P = 0.006), and more frequent disease-specific deaths (27.3% vs. 8.6%, P = 0.005) with shorter survival (12.9 vs. 34.2 months, P = 0.011). Ocular melanomas made up 15.0% of all melanomas in NF1 patients versus 1.5% in the general population ( P < 0.001). In pooling all population-based studies describing melanoma in NF1 populations, NF1 individuals had 2.55 higher odds of having melanoma compared to the general population. A nevus spilus was commonly reported among NF1 individuals with nevi (44.8%, 39/87). Our findings suggest that NF1 individuals may have a higher risk for developing melanomas and tend to have thicker melanomas and worse survival compared to the general population, highlighting the importance of cutaneous and ophthalmologic surveillance in NF1 patients. Our review also supports the association between NF1 and nevus spilus.

Nearly 15% of melanomas occur in patients with a family history and a subset of these patients have a germline mutation in a melanoma predisposing gene. CDKN2A mutations are responsible for the majority of hereditary melanoma, but many other susceptibility genes have been discovered in recent years, including CDK4, TERT, ACD, TERF2IP, POT1, MITF, MC1R, and BAP1. Additionally, melanoma risk is increased in mixed cancer syndromes caused by mutations in PTEN, BRCA2, BRCA1, RB1, and TP53. While early onset, multiple tumors, and family cancer history remain the most valuable clinical clues for hereditary melanoma, characteristic epithelioid cytology of melanocytic tumors may suggest an underlying BAP1 mutation. Herein, we review the clinical and histopathologic characteristics of melanocytic tumors associated with these germline mutations and discuss the role of genetic counseling.