Changeable naevi in people at high risk for melanoma

The long-term evolution of melanocytic nevi among high-risk adults

BACKGROUND

There is little understanding regarding the long-term natural history of melanocytic nevi among adults.

OBJECTIVE

The objective of the study was to describe the long-term natural history of individual nevi located on the torso of high-risk patients.

METHODS

All patients attending Memorial Sloan Kettering Cancer Center (MSKCC) who underwent two total body photography (TBP) sessions 15+ years apart were included ('retrospective' group). To account for a potential selection bias, we also included consecutive patients who had TBP 15+ years ago and consented to undergo follow-up TBP ('prospective' group). We compared baseline and follow-up torso images on the TBPs and evaluated the number of total, new and disappearing nevi; number of seborrheic keratoses and actinic keratoses; each nevus' diameter at both time points; each nevus' colour change; the presence of clinical atypia; and when dermoscopy was available, the dermoscopic features at each time point.

RESULTS

One hundred six patients were included in the study. Although the average age of the patients was 40 at baseline TBP, most patients developed new nevi between imaging sessions (median 16.4 years) with an average of 2.6 (SD = 4.8) nevi per participant. The average number of disappearing nevi was 0.3 (SD = 0.6). In addition, 62/106 (58%) patients had an absolute increase, and 9/106 (8%) patients had an absolute decrease in their total nevus count. Roughly half (49%: 1416/2890) of the nevi that could be evaluated at both time points increased in diameter by at least 25%. Only 6% (159/2890) of nevi shrunk in diameter by at least 25%. Patients with a history of melanoma had a higher rate of disappearing nevi, and their nevi were more likely to grow. Most nevi demonstrated no significant dermoscopic changes.

CONCLUSIONS

High-risk patients acquire new nevi throughout life with very few nevi disappearing over time. Contrary to prior reports, most nevi in adults increase in diameter, while few nevi shrink.

Suggested methodology for longitudinal evaluation of nevi based on clinical images

BACKGROUND

Melanoma screening includes the assessment of changes in melanocytic lesions using images. However, previous studies of normal nevus temporal changes showed variable results and the optimal method for evaluating these changes remains unclear. Our aim was to evaluate the reproducibility of (a) nevus count done at a single time point (method I) versus two time points (method II); and (b) manual and automated nevus diameter measurements.

MATERIALS AND METHODS

In a first experiment, participants used either a single time point or a two time point annotation method to evaluate the total number and size of nevi on the back of an atypical mole syndrome patient. A Monte Carlo simulation was used to calculate the variance observed. In a second experiment, manual measurements of nevi on 2D images were compared to an automated measurement on 3D images. Percent difference in the paired manual and automated measurements was calculated.

RESULTS

Mean nevus count was 137 in method I and 115.5 in method II. The standard deviation was greater in method I (38.80) than in method II (4.65) (p = 0.0025). Manual diameter measurements had intraclass correlation coefficient of 0.88. The observed mean percent difference between manual and automated diameter measurements was 1.5%. Lightly pigmented and laterally located nevi had a higher percent difference.

CONCLUSIONS

Comparison of nevi from two different time points is more consistent than nevus count performed separately at each time point. In addition, except for selected cases, automated measurements of nevus diameter on 3D images can be used as a time-saving reproducible substitute for manual measurement on 2D images.

Dermoscopic and clinical predictors of reflectance confocal microscopy patterns of typical nevi on the back and legs: A cross-sectional study

BACKGROUND

Nevus phenotype is a marker of melanoma risk. In vivo prediction of microscopic pattern is needed to more precisely classify nevi.

OBJECTIVE

To identify dermoscopic and clinical predictors of microscopic patterns of typical nevi.

METHODS

We used reflectance confocal microscopy (RCM) to classify microscopic patterns of nevi. We prospectively accrued adults presenting for periodic skin screening and imaged, with dermoscopy and RCM, 3 randomly selected nevi from the upper and lower back and lower extremity. RCM patterns were classified into ring, clod, meshwork, and composite types. Logistic regression was used to identify best predictors of RCM pattern.

RESULTS

The study included 310 nevi from 112 participants (mean age 44 years; 51 women). Dermoscopic reticular pattern correlated most frequently (59.9%) with RCM ring pattern, dermoscopic globular with RCM composite (56.6%) and RCM clod (35.9%), dermoscopic complex with RCM composite (76.3%), and dermoscopic homogenous with RCM clod (50.8%). Integrating dermoscopic pattern with contour, diameter, color, and anatomic location of nevi improved prediction of microscopic patterns beyond dermoscopy alone. The dermoscopic clinical regression model correctly classified lesions to RCM ring versus RCM clod in 90% and to RCM ring versus RCM composite patterns in 81%.

LIMITATIONS

The study was restricted to adults, back and lower extremities, and typical nevi.

CONCLUSIONS

Integrating dermoscopic patterns with clinical attributes may improve prediction of microscopic patterns of nevi.

'Mind your Moles' study: protocol of a prospective cohort study of melanocytic naevi

INTRODUCTION

Having many melanocytic naevi or 'moles' on the skin is the strongest predictor of melanoma; thus, much can be learnt from investigating naevi in the general population. We aim to improve the understanding of the epidemiology and biology of naevi by conducting a 3-year prospective study of melanocytic naevi in adults.

METHODS AND ANALYSIS

This is a population-based cohort study of melanocytic naevi in 200 adults aged 20-69 years recruited via the Australian electoral roll. At baseline, participants will complete a questionnaire on their sun behaviour and health and undergo a clinical examination. Three-dimensional (3D) total-body photography will be used to record the images of skin lesions. Pigmented naevi will be analysed in terms of number, diameter, colour and border irregularity using automated analysis software (excluding scalp, beneath underwear and soles of feet). All naevi ≥5 mm will be recorded using the integrated dermoscopy photographic system. A saliva sample will be obtained at baseline for genomic DNA analysis of pigmentation, naevus and melanoma-associated genes using the Illumina HumanCoreExome platform. The sun behaviour and health follow-up questionnaire, clinical examination and 3D total-body photography will be repeated every 6 months for 3 years. The first 50 participants will also undergo manual counts of naevi ≥2 mm and ≥5 mm at baseline, 6-month and 12-month follow-ups. Microbiopsy and excision of naevi of research interest is planned to commence at the 18-month time point among those who agree to donate samples for detailed histopathological and molecular assessment.

ETHICS AND DISSEMINATION

This study was approved by the Metro South Health Human Research Ethics Committee in April 2016 (approval number: HREC/16/QPAH/125). The findings will be disseminated through peer-reviewed and non-peer-reviewed publications and presentations at conferences.

A prospective observational study of pigmented naevi changes in psoriasis patients on biologic therapy

BACKGROUND/OBJECTIVES

Patients on biologic therapy are thought to be at increased risk of developing non-melanoma skin cancers and melanomas. It is unknown whether biologic therapy alters the natural history of melanocytic naevi. Therefore, a prospective observational study was conducted to determine whether psoriasis patients on biologic therapy develop changes in naevi.

METHODS

Clinical and dermoscopic assessment of all melanocytic naevi was performed in 45 psoriasis patients on biologic therapy versus a control cohort of 43 subjects, using sequential digital dermoscopic imaging and total body photography. The mean follow-up period was 1.5 years.

RESULTS

The study and control patients had comparable age, gender, previous and family history of non-melanoma skin cancers and melanomas, as well as previous sun exposure and total number of naevi. The number of naevi with major dermoscopic changes was 3% in the study and 1.9% in the control group, with an adjusted incidence rate ratio of 1.45 (95% confidence interval 0.90-2.33; P = 0.125). The rate of minor changes was 15.9% in the study group versus 19.4% in the control (adjusted incidence rate ratio 0.77, 95% confidence interval 0.57-1.08; P = 0.14). There were six new dysplastic naevi in 4/45 biologic patients and four in 4/43 controls; however, the difference was not significant (relative risk 0.96, 95% confidence interval -0.12 to 0.12; P = 0.95). There were no melanomas in either group.

CONCLUSION

Over a mean follow-up period of 1.5 years there was no evidence of significantly different changes in naevi or development of new dysplastic naevi in psoriasis patients on biologic treatment compared to controls.

Whole-Exome Sequencing of Acquired Nevi Identifies Mechanisms for Development and Maintenance of Benign Neoplasms

The melanoma transformation rate of an individual nevus is very low despite the detection of oncogenic BRAF or NRAS mutations in 100% of nevi. Acquired melanocytic nevi do, however, mimic melanoma, and approximately 30% of all melanomas arise within pre-existing nevi. Using whole-exome sequencing of 30 matched nevi, adjacent normal skin, and saliva we sought to identify the underlying genetic mechanisms for nevus development. All nevi were clinically, dermoscopically, and histopathologically documented. In addition to identifying somatic mutations, we found mutational signatures relating to UVR mirroring those found in cutaneous melanoma. In nevi we frequently observed the presence of the UVR mutation signature compared with adjacent normal skin (97% vs. 10%, respectively). Copy number aberration analysis showed that for nevi with copy number loss of tumor suppressor genes, this loss was balanced by loss of potent oncogenes. Moreover, reticular and nonspecific patterned nevi showed an increased (P < 0.0001) number of copy number aberrations compared with globular nevi. The mutation signature data generated in this study confirms that UVR strongly contributes to nevogenesis. Copy number changes reflect at a genomic level the dermoscopic differences of acquired melanocytic nevi. Finally, we propose that the balanced loss of tumor suppressor genes and oncogenes is a protective mechanism of acquired melanocytic nevi.

Dermoscopy of Malignant Skin Tumours: What's New?

Dermoscopy represents a new and effective tool that assists dermatologists in improving the accuracy of clinical diagnosis in onco-dermatology. The aim of this article is to provide an overview of the latest and important dermoscopic progress and observations in this ever-evolving field of dermatology.