Histopathologic correlates of dermoscopic criteria

Understanding the anatomy of dermoscopy of melanocytic skin tumours: Correlation in vivo with line-field optical coherence tomography

BACKGROUND

Early melanoma detection is the main factor affecting prognosis and survival. For that reason, non-invasive technologies have been developed to provide a more accurate diagnosis. Recently, line-field confocal optical coherence tomography (LC-OCT) was developed to provide an in vivo, imaging device, with deep penetration and cellular resolution in three dimensions. Combining the advantages of conventional OCT and reflectance confocal microscopy, this tool seems to be particularly suitable for melanocytic lesions.

OBJECTIVES

The objective of this study was to identify and describe the correlation between specific dermoscopic criteria and LC-OCT features in three dimensions associated with melanocytic lesions.

METHODS

Dermoscopic and LC-OCT images of 126 melanocytic lesions were acquired in three different centres. The following dermoscopic criteria have been considered: reticular pattern, dots and globules, structureless areas, blue-whitish veil, regression structures, negative network, homogeneous pattern, streaks and blotches.

RESULTS

69 (55%) benign and 57 (45%) malignant lesions were analysed. A regular reticular pattern was found associated in the 75% of the cases with the presence of elongated rete ridges with pigmented cells along the basal layer, while atypical reticular pattern showed an irregular organization of rete ridges with melanocytic hyperplasia, broadened and fused ridges and elongated nests. Both typical and atypical dots and globules were found associated with melanocytic nests in the dermis or at the dermoepidermal junction (DEJ), as well as with keratin cysts/pseudocysts. Grey globules corresponded to the presence of melanin-containing dermal inflammatory cells (melanophages) within the papillae. Structureless brown/black areas correlated with alterations of the DEJ. We observed the same DEJ alterations, but with the presence of dermal melanophages, in 36% of the cases of blue/white/grey structureless areas. A description of each LC-OCT/dermoscopy correlation was made.

CONCLUSIONS

LC-OCT permitted for the first time to perform an in vivo, 3D correlation between dermoscopic criteria and pathological-like features of melanocytic lesions.

Clinical and Dermoscopic Findings of Nevi after Photoepilation: A Review

Atypical clinical and dermoscopic findings, or changes in pigmented melanocytic lesions located on body areas treated with lasers or intense pulsed light (IPL) for hair removal (photoepilation), have been described in the literature. There are three prospective studies in a total of 79 individuals with 287 melanocytic nevi and several case reports reporting the dermoscopic findings and changes after photoepilation. Clinical changes have been reported in 20-100% of individuals, while dermoscopic changes have been observed in 48% to 93% of nevi. More frequent dermoscopic changes included bleaching, the development of pigmented globules, and irregular hyperpigmented areas and regression structures, including gray areas, gray dots/globules, and whitish structureless areas. The diagnostic approach for pigmented lesions with atypical dermoscopic findings and changes after photo-epilation included reflectance confocal microscopy, sequential digital dermoscopy follow-up, and/or excision and histopathology. Challenges pertaining to these diagnostic steps in the context of photoepilation include the detection of findings that may warrant a biopsy to exclude melanoma (ugly duckling, irregular hyperpigmented areas, blue-gray or white areas, and loss of pigment network), the potential persistence of changes at follow-up, and that a histopathologic diagnosis may not be possible due to the distortion of melanocytes or complete regression of the lesion. Furthermore, these diagnostic approaches can be time-consuming, require familiarization of the physician with dermoscopic features, may cause anxiety to the individual, and highlight that avoiding passes of the laser or IPL devices over pigmented lesions is key.

Fluorescence-advanced videodermatoscopy (FAV) for the differential diagnosis of suspicious facial lesions: A single-centre experience with pattern analysis and histopathological correlation

BACKGROUND

Fluorescence-advanced videodermatoscopy (FAV) is a new non-invasive high-resolution skin imaging technique to assess pigmented lesions in conjunction with the clinical examination and dermatoscopy.

OBJECTIVES

This is the first prospective study to identify morphologic descriptors and standardized terminology to examine facial pigmented lesions using FAV. The objectives were to identify FAV indicators, which can assist physicians in diagnosing suspicious flat facial pigmented lesions.

METHODS

Consecutive equivocal pigmented lesions were retrospective analysed. Histopathological examination was performed for all the lesions. The main cytomorphological and cytoarchitectural FAV features were described and correlated with histopathological characteristics.

RESULTS

From January to October 2020, 21 consecutive clinically suspected pigmented lesions in 20 patients were analysed using dermatoscopy and FAV and then surgically excised. Histopathological examination identified lentigo maligna (LM), lentigo maligna melanoma (LMM), solar lentigo (SL), flat seborrheic keratosis (SK) and pigmented actinic keratosis (PAK). Thirteen malignant melanocytic lesions were removed (11 LM, 2 LMM), two were diagnosed as PAK, and the remaining six pigmented lesions were SL-SKs. With FAV, large ovoid pleomorphic and dendritic cells arranged in the intrafollicular disposition, are typical of most malignant melanocytic lesions (12/13, 92.3%). No benign lesions displayed these features. In dermatoscopy, this folliculotropism corresponded to the presence of an annular-granular pattern with slate grey dots that were aggregated asymmetrically around follicular openings.

CONCLUSIONS

FAV features can provide an improved diagnostic approach in the differential diagnosis of flat pigmented facial lesions.

Basal cell carcinoma and dermal nevi of the face: comparison of localization and dermatoscopic features

BACKGROUND

Basal cell carcinoma (BCC) and dermal nevi located on the face can easily be confused on clinical examination. Little is known about the different preferential localizations of these entities, and a systematic analysis of dermatoscopic features for differential diagnosis is lacking.

METHODS

Clinical and dermatoscopic images of BCCs and dermal nevi were retrospectively evaluated to study their relation to various face anatomical areas, BCC histotype, classic and nonclassic dermatoscopic BCC criteria, as well as typical dermatoscopic criteria for dermal nevi.

RESULTS

We examined 118 BCCs and 77 dermal nevi, all having histopathological confirmation. BCCs were most frequently located on the lateral side of the forehead (12.7%), nasal dorsum (10.2%) and nasal ala (9.3%), while dermal nevi were found predominantly on the buccal area (11.8%), scalp (11.8%), and perioral region (10.8%). The prevalent dermatoscopic criteria for BCC were the classic arborizing vessels (94.1%) and arborizing microvessels (89%). The most common BCC histotype on the face was sclerodermiform (47.5%), followed by nodular (28%) and superficial (24.6%).

CONCLUSIONS

This study shows that BCCs are preferentially located on the lateral side of the forehead, nasal dorsum and nasal ala, while dermal nevi of the face are preponderantly located on the buccal area, scalp, and perioral region. The dermatoscopic features confirmed the frequency of classic and nonclassic criteria for BCCs already demonstrated in other studies. No significant site-specific features were observed for either BCCs or dermal nevi.

The differences in clinical and dermoscopic features between in situ and invasive nevus-associated melanomas and de novo melanomas

BACKGROUND

Nevus-associated melanomas (NAM) account for 30% of all melanomas and are associated with younger age and with thinner Breslow thickness. Previous studies of NAM dermoscopy found conflicting results.

OBJECTIVE

To compare the clinical and dermoscopic features of NAM and de novo melanomas (DNM), stratified by melanoma thickness, in a relatively large cohort of patients.

METHODS

A cross-sectional study of all melanomas biopsied between 2004 and 2019 at a large cancer centre. Lesions were categorized as in situ and invasive NAM or DNM. Dermoscopic images were reviewed and annotated. Associations between melanoma subtype and dermoscopic features were analysed via logistic regression modelling. Bivariate analyses were conducted using non-parametric bootstrap and chi-squared methods.

RESULTS

The study included 160 NAM (86 in situ and 74 invasive) and 218 DNM (109 in situ and 109 invasive). NAM were associated with younger age, greater likelihood of being present on the torso, and thinner Breslow thickness. NAM were 2.5 times more likely to show a negative pigment network than DNM. In situ NAM were 2.1 and two times more likely to display dermoscopic area without definable structures and tan structureless areas than DNM, respectively. In situ melanomas were more likely to present a pigment network, and invasive melanomas more commonly presented scar-like depigmentation and shiny white structures. Streaks, blotches and shiny white structures were associated with deeper Breslow depth.

CONCLUSIONS

Even though the nevus component of NAM could not be identified dermoscopically in the current series, negative pigment network, tan structureless areas and areas without definable structures are dermoscopic clues for NAM.

Defining the Molecular Genetics of Dermoscopic Naevus Patterns

Melanocytic naevi are common melanocytic proliferations that may simulate the appearance of cutaneous melanoma. Naevi commonly harbour somatic mutations implicated in melanomagenesis but in most cases lack the necessary genomic alterations required for melanoma development. While the mitogen-activated protein kinase pathway and ultraviolet radiation strongly contribute to naevogenesis, the somatic mutational landscape of dermoscopic naevus subsets distinguishes some of the molecular hallmarks of naevi in relation to melanoma. We herein discuss the classification of naevi and theories of naevogenesis and review the current literature on the somatic alterations in naevi and melanoma. This review focusses on the clinical-dermoscopic-pathological and genomic correlation of naevi that shapes the current understanding of naevi.

[Dermatoscopic-pathological correlation of melanocytic skin lesions]

There is no doubt that dermatopathology is the most important method to decide if a melanocytic lesion is benign or malignant; however, like most morphologic examinations, dermatopathology is subjective. A recent study demonstrated that the pathologic diagnosis of melanocytic skin lesions has a high variability. Reports with false-positive or false-negative diagnoses are relatively common. The pathologic examination of melanocytic lesions also has observer-independent limitations and one has to accept that some melanocytic lesions cannot be classified as benign or malignant with confidence by dermatopathology alone. If a confident diagnosis is not possible a dermatoscopic-pathologic correlation may be helpful. This, however, is only possible if dermatoscopic images are available and if the dermatopathologist knows how to interpret dermatoscopic structures. A dermatoscopic-pathologic correlation is not useful in all difficult melanocytic lesions but it should be considered in difficult flat pigmented lesions. In these cases dermatoscopy may provide even more important additional information than molecular findings.

A risk scoring system for the differentiation between melanoma with regression and regressing nevi

BACKGROUND

Spontaneous regression of melanomas is relatively common, its prevalence ranging from 10 to 35%. However, regressing nevi can exhibit worrisome feature and simulate melanoma both clinically and dermoscopically. Thus, the presence of regression can represent a confounding factor.

OBJECTIVE

To investigate the frequency of dermoscopic patterns of "regression" in a series of benign and malignant melanocytic skin lesions, and to design an integrated scoring system. Scoring classifiers are very effective in selecting the significant parameters for discriminating two clinical conditions, thus can rapidly calculate a patient's risk for a given disease.

METHODS

We selected a series of 95 regressing melanocytic lesions, including 50 regressing nevi and 45 melanomas with regression. For each lesion, 12 dermoscopic variables (i.e. five types of regression structures, five atypical pigmentation structures, atypical vascular pattern and pink areas) were examined by three expert in dermoscopy (blinded to the histological diagnosis). The dermoscopic evaluation was then combined with patient age, gender, body site and the maximum diameter of lesion. Concordance analysis with Cohen's kappa was performed between the three clinicians. A risk scoring system was designed by the leave-one-out cross-validation procedure to ensure model prediction power.

RESULTS

The predictive score model revealed a sensitivity of 97.8% and a specificity of 75.5% in discriminating nevi and melanomas with regression. Using the score model, the diagnostic performance of the examiners increased by an average of 23.7% in sensitivity and 5.9% in specificity, compared with standard dermoscopic pattern analysis.

CONCLUSIONS

We assessed the validity of an integrated risk scoring model as a new methodological approach that could help the dermatologist in the differentiation between melanoma with regression and regressing nevus. Future studies could test the setting up of a score model over an even more complex pool of data obtained from different skin lesions with various diagnostic devices.

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.

Computer aided diagnostic support system for skin cancer: a review of techniques and algorithms

Image-based computer aided diagnosis systems have significant potential for screening and early detection of malignant melanoma. We review the state of the art in these systems and examine current practices, problems, and prospects of image acquisition, pre-processing, segmentation, feature extraction and selection, and classification of dermoscopic images. This paper reports statistics and results from the most important implementations reported to date. We compared the performance of several classifiers specifically developed for skin lesion diagnosis and discussed the corresponding findings. Whenever available, indication of various conditions that affect the technique's performance is reported. We suggest a framework for comparative assessment of skin cancer diagnostic models and review the results based on these models. The deficiencies in some of the existing studies are highlighted and suggestions for future research are provided.

Grey-blue regression in melanoma in situ-evaluation on 111 cases

As fibrosis and melanosis are often seen in malignant melanoma, the presence of dermoscopic signs of regression may represent a clue for the diagnosis of malignancy. Our aim was to assess the frequency and extent of 11 dermoscopic features of regression evaluating dermoscopic images of 111 melanomas in situ (MIS). Regression structures (grey-blue areas, white areas, peppering, and/or blue-whitish veil) were present in 80.1% of the lesions. Approximately 80% of the lesions showed regression of dermoscopic structures and light brown areas. Most lesions showed the presence of grey-blue areas (74.7%), whereas peppering was observable in 30.6% of MIS. Areas of fibrosis were mainly observable as structureless areas with a pinkish hue (50.4%). Based on our data, the reticular pattern of blue regression and light brown areas can be considered a significant discriminator and a reliable predictor of MIS.

Reticular grey-blue areas of regression as a dermoscopic marker of melanoma in situ

BACKGROUND

By dermoscopy, regression structures are substantially defined by the presence of white and blue areas in the lesion image. As fibrosis and melanosis are often seen in malignant melanoma (MM), the presence of dermoscopic signs of regression may represent a clue for the diagnosis of malignancy.

OBJECTIVES

To assess the frequency and extent of dermoscopic signs of regression in melanoma in situ (MIS) and to describe its dermoscopic features.

METHODS

Dermoscopic images of 85 MIS, 85 invasive MMs and 85 dermoscopically equivocal lesions with a histological diagnosis of naevus were evaluated by three dermatologists, who assessed the presence of 11 parameters of regression.

RESULTS

The number of regression parameters per lesion increased according to melanoma thickness. White areas, the grey-blue veil and widespread blue areas were more frequent in invasive MMs than in the other two lesion groups, whereas light brown areas and regression of dermoscopic structures were more frequent in MIS. Peppering was observable in the same percentage of MIS and invasive MMs. Blue areas were more frequently structureless in equivocal lesions and invasive MMs, whereas the reticular pattern prevailed in MIS.

CONCLUSIONS

Frequency, morphology, extent and distribution of regression vary according to melanoma thickness and diameter. Lesions with reticular blue regression and light brown areas should undergo surgical excision for the suspicion of MIS. Moreover, the identification of the reticular pattern of blue regression can be considered a significant discriminator and a reliable predictor of MIS.

Melanocytic aggregation in the skin: diagnostic clues from lentigines to melanoma

Pigmented skin lesions are among the most common skin lesions. Among them, melanocytic proliferations are morphologically diverse and their behavior may be difficult to discern with certainty. Researchers must be able to distinguish melanocytic from nonmelanocytic pigmented skin lesions and, in particular, benign from malignant lesions. The majority of these lesions can be diagnosed with ease; however, a minority of cases is difficult and have potential for error. The authors have systematically analyzed the clinical and dermoscopic features of melanocytic skin lesions, so as to increase in vivo diagnostic accuracy.

Nonmelanocytic Lesions Defying the Two-Step Dermoscopy Algorithm

The first step of the two-step algorithm of dermoscopy aims at differentiating melanocytic from nonmelanocytic pigmented lesions, using a stepwise evaluation for the presence of specific dermoscopic criteria. The purpose of this article is to heighten awareness of clinicians to nonmelanocytic lesions that defy the two-step algorithm, thus simulating melanocytic lesions dermoscopically. Seborrheic keratosis, solar lentigo, dermatofibroma, and supernumerary accessory nipple may present with network-like structures. Seborrheic keratosis, dermatofibroma, subcorneal hemorrhage, basal cell carcinoma (BCC), and cutaneous metastases of breast and other cancers may contain pigmented globules. Peripheral streaks can also be seen in seborrheic keratosis and BCC. Homogenous bluish pigmentation, simulating a blue nevus, can also be seen in benign vascular lesions, Kaposi sarcoma, radiation tattoo, and BCC. This overlap of features between melanocytic and nonmelanocytic lesions suggests that integration of all dermoscopic features in the lesion, rather than a stepwise evaluation, may facilitate reaching the correct diagnosis in select cases as outlined in this article.

Correlation with digital dermoscopic images can help dermatopathologists to diagnose equivocal skin tumours

BACKGROUND

A variety of pigmented skin tumours can lead to diagnostic difficulties in dermatopathology.

OBJECTIVES

To investigate whether the interobserver agreement between histopathological diagnoses of equivocal pigmented tumours made by two referral centres can be improved by additional use of dermoscopic images.

MATERIAL AND METHODS

Retrospective study using 160 tumours excised in the pigmented skin lesions clinic in Graz and 141 from Tübingen. Tumours were diagnosed in the referring centres using clinical data, histopathology and, if required, immunohistochemistry. The tumours were initially diagnosed as 74 melanomas, 218 melanocytic naevi and nine nonmelanocytic tumours. Haematoxylin and eosin sections, patients' age and sex, tumour localization and digital dermoscopic images were then exchanged between the participating centres. Then, diagnoses were made initially based solely on dermatopathology and clinical information. After a washout phase, the same sections were reevaluated with the additional use of dermoscopic images. The main outcome measures were the Cohen's kappa-coefficients of the initial diagnoses of the centre submitting the cases and the diagnoses of the other centre without and with dermoscopy.

RESULTS

The kappa-coefficient between the initial diagnoses with those made by the second centre without dermoscopy was 0.90 in Graz, 0.73 in Tübingen, and 0.81 overall. With the additional use of dermoscopy the kappa-value was invariably high with 0.89 in Graz, and improved to 0.87 in Tübingen, and to 0.88 overall.

CONCLUSIONS

The additional use of digital dermoscopic images further improved the overall very good agreement of histopathological diagnoses between two referral centres.

Features of regression in dermoscopic diagnosis: a confounding factor? Two clinical, dermoscopic-pathologic case studies

BACKGROUND

In dermoscopy, the presence of regression areas is generally associated with melanocytic lesions and is often considered a clue of malignancy. However, some lesions included in the differential diagnosis of melanoma may show dermoscopic regression parameters. Regression may indeed be one of the most confounding dermoscopic parameters because it tends to cover, or rather to destroy, other parameters, thus often hindering a correct diagnosis.

OBJECTIVE

We propose to raise the issue of the actual diagnostic role of this parameter.

METHODS

We discuss two clinical cases (melanoma and basal cell carcinoma) with major dermoscopic regression features.

CONCLUSION

Dermoscopic regression parameters should not be regarded as almost pathognomonic signs of melanocytic lesions. Rather, they should be taken into account only after having considered other dermoscopic parameters of greater diagnostic significance and just as signs that may better typify the lesion.

Dermoscopy and its role in diagnosing melanocytic lesions: a guide for pathologists

Dermoscopy (surface microscopy) is a clinical technique which uses a hand-held magnifying instrument, usually with liquid at the skin-instrument interface, to examine pigmented lesions on the skin surface. A magnification of x 10 is usually used. Dermoscopy assists in deciding if the lesion should be excised or biopsied, requires monitoring or can be safely left in situ. The technique provides a bridge between the naked eye appearance of a lesion and the histopathological examination. Multiple dermoscopic features have been described and many of their histological correlates have been determined. Dermoscopic diagnosis usually involves a two-step procedure. The first step is to decide if the lesion is melanocytic or not. If melanocytic, the second step is to decide if the lesion is benign or malignant. Multiple algorithms have been developed to help in this decision. Dermoscopic criteria have been developed for melanoma and naevi. Several non-melanocytic pigmented lesions can be diagnosed with dermoscopy, including pigmented basal cell carcinoma, seborrhoeic keratoses, haemangioma and lichen planus-like keratosis.

Instruments and new technologies for the in vivo diagnosis of melanoma

The principal objective of screening individuals at risk for melanoma is detection of cutaneous melanoma during the curable stages of its early evolution. Unaided visual inspection of the skin is often suboptimal at diagnosing melanoma. Improving the diagnostic accuracy for melanoma remains an area of active research. These research efforts have focused on both the detection of early melanoma and the in-depth evaluation of suspicious pigmented lesions for the presence or absence of melanoma. Numerous instruments are under investigation to determine their usefulness in imaging and ascertaining a correct in vivo diagnosis of melanoma. It is anticipated that some of these tools, alone or in combination, will improve our ability to differentiate, in vivo, melanoma from its simulators. Ultimately, these advances may prevent unnecessary biopsies (increased specificity) while increasing the sensitivity for diagnosing melanoma. This article reviews the current instruments and new technologies for the in vivo diagnosis of melanoma. Learning objective At the conclusion of this learning activity, participants should be acquainted with the instruments designed to facilitate the early detection of melanoma. They should also be familiar with the basic technology behind these instruments and should recognize the potential benefits and limitations inherent in each.

[Correlation between dermoscopy and histopathology in pigmented and non-pigmented skin tumours]

Dermoscopy (dermatoscopy, epiluminescence microscopy, surface microscopy) is a non-invasive method in dermatology. With this method pigmented and non-pigmented skin tumours can be diagnosed with a clear higher sensitivity and specificity compared to clinical examination. Malignant skin tumours are detected earlier and unnecessary excisions of benign skin tumours can be avoided. The knowledge about the correlation between dermoscopy and histopathology is hereby an essential condition. In this continuing medical education article the correlation of both examination techniques is presented for the dermoscopic differential diagnoses.

Dermoscopy: a review

In this article, dermoscopy, an in vivo technique that allows the clinician to evaluate subsurface structures, is described. Dermoscopy is used in the evaluation of pigmented lesions of the skin and is a helpful tool in the differential diagnosis. This article discusses research on dermoscopy, as well as other imaging techniques including confocal microscopy, digital dermoscopy, and computer-assisted diagnosis.