Introduction to dermoscopy

Advances in Early Detection of Melanoma and the Future of At-Home Testing

The past decade has seen numerous advancements in approaches to melanoma detection, each with the common goal to stem the growing incidence of melanoma and its mortality rate. These advancements, while well documented to increase early melanoma detection, have also garnered considerable criticism of their efficacy for improving survival rates. In this review, we discuss the current state of such early detection approaches that do not require direct dermatologist intervention. Our findings suggest that a number of at-home and non-specialist methods exist with high accuracy for detecting melanoma, albeit with a few notable concerns worth further investigation. Additionally, research continues to find new approaches using artificial intelligence which have promise for the future.

Quantitative Multispectral Imaging Differentiates Melanoma from Seborrheic Keratosis

Melanoma is a melanocytic tumor that is responsible for the most skin cancer-related deaths. By contrast, seborrheic keratosis (SK) is a very common benign lesion with a clinical picture that may resemble melanoma. We used a multispectral imaging device to distinguish these two entities, with the use of autofluorescence imaging with 405 nm and diffuse reflectance imaging with 525 and 660 narrow-band LED illumination. We analyzed intensity descriptors of the acquired images. These included ratios of intensity values of different channels, standard deviation and minimum/maximum values of intensity of the lesions. The pattern of the lesions was also assessed with the use of particle analysis. We found significantly higher intensity values in SKs compared with melanoma, especially with the use of the autofluorescence channel. Moreover, we found a significantly higher number of particles with high fluorescence in SKs. We created a parameter, the SK index, using these values to differentiate melanoma from SK with a sensitivity of 91.9% and specificity of 57.0%. In conclusion, this imaging technique is potentially applicable to distinguish melanoma from SK based on the analysis of various quantitative parameters. For this application, multispectral imaging could be used as a screening tool by general physicians and non-experts in the everyday practice.

Clinicopathological characterization of mouse models of melanoma

Mouse models of melanoma have proven invaluable in the delineation of key molecular events involved in disease progression in humans and provide potential preclinical models for therapeutic testing (Damsky and Bosenberg, Pigment Cell Melanoma Res 25(4):404-405, 2012; Walker et al., Pigment Cell Melanoma Res 24(6):1158-1176, 2011). Here we concentrate on the clinicopathological analysis of melanocytic tumors.

Negative pigment network and shiny white streaks: a dermoscopic-pathological correlation study

It has been suggested that both negative pigment network (NPN) and shiny white streaks (SWS) were related to an increase of dermal collagen. To study precisely the dermoscopic-histopathologic correlation of NPN and SWS, we have performed a dermoscopic-pathological correlation study. A total of 25 skin lesions dermoscopically characterized by the presence of NPN and/or SWS, including histopathologically confirmed dermatofibroma (2), Spitz nevus (3), compound nevus (6), dysplastic nevus (7), and melanoma (7), were evaluated for the presence of NPN, SWS, and blue-white veil. The histopathologic features such as orthokeratosis, orthokeratosis plus nests of pigmented melanocytes at the junction, hypergranulosis, hypergranulosis plus nests of pigmented melanocytes at the junction, epidermal invagination plus orthokeratosis, fibrosis, lamellar fibrosis, and elongation and bridging of rete ridges were evaluated. We found a disagreement in 80% of skin lesions between NPN and fibrosis (P = 0.02). For SWS, a significant agreement emerged with hypergranulosis (76%; P = 0.01), and the same occurred with fibrosis (80%; P = 0.01). Moreover, blue-white veil also displayed a significant agreement with hypergranulosis (68%; P = 0.04). Our findings confirm the correlation of SWS with fibrosis, whereas a clear-cut histopathologic substrate of NPN could not be established.

Negative pigment network: an additional dermoscopic feature for the diagnosis of melanoma

BACKGROUND

The negative pigment network (NPN) is seen as a negative of the pigmented network and it is purported to be a melanoma-specific structure.

OBJECTIVES

We sought to assess the frequency, sensitivity, specificity, and odds ratios (ORs) of NPN between melanoma cases and a group of control lesions.

METHODS

Digitalized images of skin lesions from 679 patients with histopathological diagnosis of dermatofibroma (115), melanocytic nevus (220), Spitz nevus (139), and melanoma (205) were retrospectively collected and blindly evaluated to assess the presence/absence of NPN.

RESULTS

The frequency of occurrence of NPN was higher in the melanoma group (34.6%) than in Spitz nevus (28.8%), melanocytic nevus (18.2%), and dermatofibroma (11.3%) groups. An OR of 1.8 emerged for the diagnosis of melanoma in the presence of NPN as compared with nonmelanoma diagnosis. Conversely, for melanocytic nevi and dermatofibromas the OR was very low (0.5 and 0.3, respectively). For Spitz nevi the OR of 1.1 was not statistically significant. When comparing melanoma with dermatofibroma, melanocytic nevus, and Spitz nevus, we observed a significantly higher frequency of multicomponent pattern (68.1%), asymmetric pigmentation (92.9%), irregularly distributed NPN (87.3%), and peripheral location of NPN (66.2%) in melanomas.

LIMITATIONS

Further studies can provide the precise dermoscopic-histopathologic correlation of NPN in melanoma and other lesions.

CONCLUSIONS

The overall morphologic pattern of NPN, such as the irregular distribution and the peripheral location of NPN, along with the multicomponent pattern and the asymmetric pigmentation could be used as additional features in distinguishing melanoma from Spitz nevus and other benign lesions.

Structural Correlations Between Dermoscopic Features of Cutaneous Melanomas and Histopathology Using Transverse Sections

Interpretation of dermoscopic features of cutaneous melanoma is based on histologic description of perpendicular sections of the lesions that does not reflect the overview achieved by epiluminescence. We describe the utilization of transverse sections as a tool to define the histopathology of features that are the dermoscopic hallmarks of cutaneous melanoma. From a collection of 23 pigmented lesions with the dermoscopic diagnosis of cutaneous melanoma submitted for surgical excision we selected, from each specimen, one dermoscopic feature (black dots and globules, brown dots, blues dots and globules, depigmentation, broadened network, radial streams or pseudopods) that was sampled with a 4-mm punch (specimen) to obtain perpendicular and transverse sections. Using this strategy, it was possible to correlate the histopathology of all features that are often used as criteria for diagnostic dermoscopy. The black dots were pigmented neoplastic cells at the dermal-epidermal junction (DEJ) and within the epidermis in heavily pigmented columns. Similar findings were seen in brown dots, however there was slightly less pigment. No statistical difference was observed between brown dots and black dots regarding size, area and number of atypical cellnests. Blue dots correlated to melanophages, surrounding the superficial vascular plexus. Depigmentation was characterized by intense fibrosis of the papillary dermis. The pigmented network showed atypical pigmented or non-pigmented melanocytes at the DEJ and epidermis as well as heavily pigmented keratinocytes in the basal cell layer. The radial streaming and pseudopods had neoplastic cells in nests, a stratified growth pattern arranged in centrifugal linear extensions, resembling a arborescent branching. The results represented herein, are an important tool for understanding histopathological alterations responsible for dermoscopic features and for improving the efficacy of this diagnostic method.

Dermoscopy for Congenital Melanocytic Nevi

Small and medium congenital melanocytic nevi are relatively common but present a small but significant risk of malignant transformation. Because prophylactic excision of all nevi is impractical, dermoscopic evaluation has a role in the clinical decision-making process. Dermoscopy of benign congenital nevi reveals a globular or homogenous pattern, black or brown dots and globules, small milia-like cysts within the globules, and terminal hairs. Dermoscopic criteria of melanoma are outlined here, with discussion of common scoring methods, the seven-point checklist, the ABCD rule, pattern analysis, and the Menzies criteria. Serial examination of congenital nevi with dermoscopy and excision of those lesions with malignant criteria are useful in the management of congenital melanocytic nevi.

An evaluation of dermoscopy fluids and application techniques

BACKGROUND

Dermoscopy, a noninvasive technique used to help physicians better visualize pigmented skin lesions, is becoming widely used by dermatologists. Yet despite its popularity, to our knowledge basic aspects such as the best immersion fluid (IF) to use and proper procedures for applying the IF and dermatoscope have never been the subject of a systematic investigation.

OBJECTIVES

To determine the best techniques for application of IF and the dermatoscope; to discover which IF results in the least amount of air inclusions; to determine which IF provides the best image quality.

MATERIALS AND METHODS

This study was divided into three phases. Phase I examined several techniques of taking digital dermoscopic photographs in an attempt to eliminate air bubbles. Phase II tested seven IFs to analyse quantitatively the number of air inclusions for each IF. Phase III investigated these same IFs to judge the image quality for each.

RESULTS

Phase I: in our hands, the best technique to apply an IF is to use an eyedropper and place the IF directly onto the skin in combination with a 'roll-on technique': the dermatoscope's edge is placed on the skin first and is then rotated until the glass plate lies flat against the skin. Phase II: the alcoholic IF resulted in the least amount of air bubble inclusions (70% ethanol, 90% isopropanol and alcoholic disinfectant), while liquid paraffin (a mineral oil) resulted in the most air bubbles. Phase III: dermoscopic structures were equally clear with alcohols and liquid paraffin, but slightly blurry with ultrasound gel and water.

CONCLUSIONS

Although 90% isopropanol performed slightly better in terms of air inclusions, we prefer to use 70% ethanol in most circumstances because it has the advantage of being odourless, unlike its counterpart. Additionally, ethanol will not stain clothing, does not crystallize on the dermatoscope, disinfects and evaporates immediately (does not need to be wiped off). For certain local considerations, such as dermoscopy on mucosa or the nail, we prefer to use ultrasound gel because it will not flow.