Clinical and dermoscopic clues to differentiate pigmented nail bands: an International Dermoscopy Society study

Prevalence of subungual melanoma in patients with cutaneous malignant melanoma: A systematic review and meta-analysis

BACKGROUND

Subungual melanoma (SUM) is a rare type of cutaneous malignant melanoma (CMM) associated with poor prognosis, while data regarding its prevalence are scarce.

OBJECTIVES

We sought to provide a comprehensive systematic review and meta-analysis of the prevalence rates of SUM among all types of CMM, considering certain demographic and clinical characteristics.

METHODS

The MEDLINE electronic database was searched systematically to identify eligible studies providing prevalence rate estimates of SUM in patients with CMM. Included studies were further analysed to estimate the relative prevalences of SUM according to study design, study years, geographical region and sex distribution.

RESULTS

Twenty-eight studies met the inclusion criteria. The overall SUM prevalence was 1.9% (95% CI [1.5%-2.3%]). The prevalence of SUM did not differ significantly between population- and hospital-based studies and remained stable over time. However, it was found to be significantly higher in Asians compared to patients of other geographical regions as well as in studies with more men than women compared to those with female preponderance (p < 0.001).

CONCLUSIONS

In all, the overall SUM prevalence among all subtypes of CMM was estimated at 1.9%, without significant changes over time, and was found to exhibit significant variability between subgroups of different geographical regions.

Seven Plus One Steps to Assess Pigmented Nail Bands (Melanonychia Striata Longitudinalis)

Melanonychia striata longitudinalis might involve one or more fingers and/or toes and might result from several different causes, including benign and malignant tumors, trauma, infections, and activation of melanocytes that might be reactive or related to the pigmentary trait, drugs and some rare syndromes. This broad differential diagnosis renders the clinical assessment of melanonychia striata particularly challenging. Nail matrix melanoma is relatively rare, occurs almost always in adults involves more frequently the first toe or thumb. The most common nail unit cancer, squamous cell carcinoma / Bowen disease (SCC) of the nail matrix is seldom pigmented. Histopathologic examination remains the gold standard for melanoma and SCC diagnosis, but excisional or partial biopsies from the nail matrix require training and is not routinely performed by the majority of clinicians. Furthermore, the histopathologic evaluation of melanocytic lesions of the nail matrix is particularly challenging, since early melanoma has only bland histopathologic alterations. Dermatoscopy of the nail plate and its free edge significantly improves the clinical diagnosis, since specific patterns have been associated to each one of the causes of melanonychia. Based on knowledge generated and published in the last decades, we propose herein a stepwise diagnostic approach for melanonychia striata longitudinalis: 1) Hemorrhage first 2) Age matters 3) Number of nails matters 4) Free edge matters 5) Brown or gray? 6) Size matters 7) Regular or irregular and, finally, "follow back".

Dermoscopy of melanoma according to different body sites: Head and neck, trunk, limbs, nail, mucosal and acral

Effective cancer screening detects early-stage tumours, leading to a lower incidence of late-stage disease over time. Dermoscopy is the gold standard for skin cancer diagnosis as diagnostic accuracy is improved compared to naked eye examinations. As melanoma dermoscopic features are often body site specific, awareness of common features according to their location is imperative for improved melanoma diagnostic accuracy. Several criteria have been identified according to the anatomical location of the melanoma. This review provides a comprehensive and contemporary review of dermoscopic melanoma criteria according to specific body sites, including frequently observed melanoma of the head/neck, trunk and limbs and special site melanomas, located on the nail, mucosal and acral region.

Clinical and dermoscopic features of nail unit melanoma in an Australian nail clinic cohort

Nail unit melanoma carries diagnostic challenges conferring with its poor prognosis. This audit aims to characterise both clinical and dermoscopic features of nail unit malignant lesions and compare them with biopsied benign lesions. It focuses on informing future practice by aiding in the stratification and recognition of malignant diagnostic patterns in the Australian context.

Nail Apparatus Melanoma: Current Management and Future Perspectives

Nail apparatus melanoma (NAM) is a rare type of cutaneous melanoma that belongs to the acral melanoma subtype. NAM is managed principally in accordance with the general treatment for cutaneous melanoma, but there is scarce evidence in support of this in the literature. Acral melanoma is genetically different from non-acral cutaneous melanoma, while recently accumulated data suggest that NAM also has a different genetic background from acral melanoma. In this review, we focus on recent advances in the management of NAM. Localized NAM should be surgically removed; amputation of the digit and digit-preserving surgery have been reported. Sentinel lymph node biopsy can be considered for invasive NAM for the purpose of accurate staging. However, it is yet to be clarified whether patients with metastatic sentinel lymph nodes can be safely spared completion lymph node dissection. Similar to cutaneous melanoma, immune checkpoint inhibitors and BRAF/MEK inhibitors are used as the first-line treatment for metastatic NAM, but data on the efficacy of these therapies remain scarce. The therapeutic effects of immune checkpoint inhibitors could be lower for NAM than for cutaneous melanoma. This review highlights the urgent need to accumulate data to better define the optimal management of this rare melanoma.

Disorders of hyperpigmentation. Part I. Pathogenesis and clinical features of common pigmentary disorders

Disorders of hyperpigmentation are common and, depending on the extent and location of involvement, can affect the quality of life and pose a significant psychologic burden for patients. Given the similarities in presentation of the various causes of hyperpigmentation, it is often difficult to elucidate the etiology of these conditions, which is important to guide management. Furthermore, certain disorders, such as lichen planus pigmentosus and ashy dermatosis, have similar clinical and/or histologic presentations, and their classification as distinct entities has been debated upon, leading to additional confusion. In this review, the authors selected commonly encountered disorders of hyperpigmentation of the skin, subdivided into epidermal, dermal, or mixed epidermal-dermal disorders based on the location of pigment deposition, along with disorders of hyperpigmentation of the mucosa and nails. Melanocytic nevi, genetic disorders, and systemic causes of hyperpigmentation were largely excluded and considered to be outside the scope of this review. We discussed the pathogenesis of hyperpigmentation as well as the clinical and histologic features of these conditions, along with challenges encountered in their diagnosis and classification. The second article in this 2-part continuing medical education series focuses on the medical and procedural treatments of hyperpigmentation.

Clinical and dermoscopic findings of benign longitudinal melanonychia due to melanocytic activation differ by skin type and predict likelihood of nail matrix biopsy

BACKGROUND

Longitudinal melanonychia (LM) is a common dermatologic finding in clinical practice with a broad differential diagnosis. Melanocytic activation is the most common LM etiology.

OBJECTIVE

To investigate clinical and dermoscopic differences of benign LM based on Fitzpatrick skin type and in biopsied vs. non-biopsied patients.

METHODS

A 10-year retrospective cohort of 248 benign LM cases at Weill Cornell Dermatology was identified and analyzed.

RESULTS

Darker-skinned vs. lighter-skinned patients had higher band width percentage (p=0.0125), lower band brightness (p<0.001), more band changes (p=0.0071), and received more biopsies (p=0.032). Biopsied (n=47) vs. non-biopsied patients (n=201) had less multidigit band involvement (p=0.0008), higher band width percentage (p=0.0213), lower band brightness (p=0.0003), and more band changes (p<0.0001). Darker skin types more often had brown vs. grey coloration on dermoscopy (p=0.0232). Mean band width percentage for all biopsied patients was 30.81% (range: 5.80%-100%).

LIMITATIONS

Single-center retrospective design. Subungual melanoma and other benign LM etiologies were not analyzed. Only 18.95% of patients received a biopsy.

CONCLUSION

Darker vs. lighter skin types more often present with darker and wider bands, brown vs. grey coloration on dermoscopy, and receive more biopsies. Multi-institutional studies on LM are needed to determine nail matrix biopsy criteria in different skin types.

Subungual Melanocytic Lesions in Pediatric Patients

The study of subungual melanocytic lesions can present challenges because of the clinical and histologic characteristics of the nail unit and the difficulty of performing nail biopsies and processing specimens. These lesions can be even more challenging in children due to differences in clinical and epidemiological profiles between the adult and pediatric populations. Many of the clinical features of subungual melanocytic lesions that would raise alarm in an adult do not have the same implications in children. Consensus is also lacking on when a nail biopsy is needed to rule out malignancy in the pediatric setting. In view of these considerations and the rarity of subungual melanoma in childhood, the recommended approach in most cases is a watch-and-wait strategy. Subungual melanocytic lesions in children may also show atypical histopathologic features that are not necessarily associated with aggressive behavior. Subungual melanoma is very rare in childhood, with just 21 cases described to date. None of the patients developed visceral metastasis or died as a result and the diagnosis was controversial in many of the cases. Considering the above and the significantly higher frequency and particular characteristics of longitudinal melanonychia with a benign etiology in children, subungual melanocytic lesions should be managed differently in this setting than in adults. In most cases, a watch-and-wait approach is the most appropriate strategy.

An Evidence-Based Approach to Pediatric Melanonychia

Melanonychia including melanonychia striata in children poses a diagnostic dilemma. Atypical clinical features often raise the possibility of malignancy, and a nail unit biopsy may be recommended. Commensurate with atypical clinical features, the histopathology may also appear alarming. However, accumulating data illustrate that most cases of melanonychia striata are benign and suggest that an alternate approach is often warranted for pediatric patients. Herein, we review the existing data regarding pediatric melanonychia striata and offer an evidence-based approach to its evaluation and management.

Evolution of the Clinical, Dermoscopic and Pathologic Diagnosis of Melanoma

The conventional narrative states that the steadily rising incidence of melanoma among fair-skinned Caucasian populations during the last decades is caused by excessive UV-exposure. There is, however, no doubt that other factors had a significant impact on the rising incidence of melanoma. Pre-1980s the clinical diagnosis of melanoma was based on gross criteria such as ulceration or bleeding. Melanomas were often diagnosed in advanced stages when the prognosis was grim. In the mid-1980s education campaigns such as the propagation of the ABCD criteria, which addressed health care professionals and the public alike, shifted the focus towards early recognition. Dermatoscopy, which became increasingly popular in the mid-1990s, improved the accuracy for the diagnosis of melanoma in comparison to inspection with the unaided eye, especially for flat and small lesions lacking ABCD criteria. At the same time, pathologists began to lower their thresholds, particularly for the diagnosis of melanoma in situ. The melanoma epidemic that followed was mainly driven by an increase in the number of in situ or microinvasive melanomas. In a few decades, the landscape shifted from an undercalling to an overcalling of melanomas, a development that is now met with increased criticism. The gold standard of melanoma diagnosis is still conventional pathology, which is faced with low to moderate interobserver agreement. New insights in the molecular landscape of melanoma did not translate into techniques for the reliable diagnosis of gray zone lesions including small lesions. The aim of this review is to put our current view of melanoma diagnosis in historical context and to provide a narrative synthesis of its evolution. Based on this narrative I will provide suggestions on how to rebuild the trust in melanoma diagnosis accuracy and in the benefit of early recognition.

Nails and COVID-19 - A comprehensive review of clinical findings and treatment

The SARS‐CoV‐2 infection, responsible for COVID‐19, has raised the interest for infection‐associated muco‐cutaneous symptoms. While dermatologic symptoms in general gained an increasing awareness, affection of the nail organ has been mentioned only recently. We provide a narrative review on COVID‐19 manifestation on the nail organ and add symptoms induced by personal protective measures and SARS‐CoV‐2 vaccination. Available treatment options are discussed.

Melanoma in Singapore: A 20-year review of disease and treatment outcomes

INTRODUCTION

Melanomas in Asians have different clinicopathological characteristics and prognosis from melanomas in Caucasians. This study reviewed the epidemiology and treatment outcomes of cutaneous melanoma diagnosed at a tertiary referral dermatology centre in Singapore, which has a multiracial population. The study also determined whether Asians had comparable relapse-free and overall survival periods to Caucasians in Singapore.

METHOD

This is a retrospective review of cutaneous melanoma cases in our centre between 1996 and 2015.

RESULTS

Sixty-two cases of melanoma were diagnosed in 61 patients: 72.6% occurred in Chinese, 19.4% in Caucasians and 3.2% in Indians, with an over-representation of Caucasians. Superficial spreading melanoma, acral lentiginous melanoma and nodular melanoma comprised 37.1%, 35.5% and 22.6% of the cases, respectively. The median time interval to diagnosis was longer in Asians than Caucasians; median Breslow's thickness in Asians were significantly thicker than in Caucasians (2.6mm versus 0.9mm, P=0.018) and Asians tend to present at a later stage. The mortality rates for Asians and Caucasians were 52% and 0%, respectively.

CONCLUSION

More physician and patient education on skin cancer awareness is needed in our Asian-predominant population for better outcomes.

Subungual Melanocytic Lesions: Key Clinical and Pathologic Concepts and Biopsy Techniques

Both dermatologists and pathologists sometimes find daunting the evaluation of melanonychia (especially subungual melanocytic lesions) because of the fear of performing nail surgery due to the risk of dystrophy, difficulties processing and interpreting nail biopsy specimens, and a general lack of experience in the field. Nevertheless, mastery of nail biopsy techniques, correct processing and orientation of specimens, and familiarity with the histologic particularities of the nail apparatus can attenuate the undoubted complexity and facilitate the tasks involved. Longitudinal excision is the biopsy technique that ensures the simplest histologic interpretation, and it is associated with a low risk of nail dystrophy when performed correctly. Clinical and epidemiological data are crucial. Subungual melanoma in childhood, for instance, is very rare and even lesions with atypical clinical and/or histologic features are probably benign. The presence of suprabasal melanocytes and other findings that would suggest malignancy at other sites are considered normal in the nail apparatus. Subungual melanoma shows a lentiginous pattern in the early stages of disease, and detection of an inflammatory infiltrate accompanying atypical lentiginous subungual lesions would appear to be one of the first diagnostic findings.

Dermoscopic features of neoplasms in skin of color: A review

BACKGROUND

Dermoscopy is undoubtedly a useful tool to improve diagnostic accuracy and minimize the number of unnecessary biopsies. However, much of the literature on dermoscopy focuses on findings in lighter-skin phototypes, leaving potential gaps of knowledge regarding its use in skin of color (SoC). As the clinical applications of dermoscopy continue to increase, understanding dermoscopic patterns in SoC is imperative.

OBJECTIVE

This review discusses the literature on dermoscopic findings of neoplasms in SoC, highlighting unique and characteristic dermoscopic features.

METHODS

A literature review was performed using the PubMed database. Case reports, case series, case-control studies, and systematic reviews were included.

RESULTS

A total of 8326 studies were identified based on the selected search terms, and 41 were included in this review based on relevance.

CONCLUSION

There are specific dermoscopic characteristics in SoC for benign nevi, acral lentiginous melanoma, ethnic melanonychia, and dermatofibroma; however, there is a lack of published data about specific features of cutaneous melanoma, subungual melanoma, pigmented basal cell carcinoma, and pigmented squamous cell carcinoma in SoC. Because pigmented basal cell carcinoma, pigmented squamous cell carcinoma, ethnic melanonychia, and acral lentiginous melanoma are diagnosed at later stages in this population, it is important to understand their dermoscopic features. Further descriptive studies are needed to better characterize unique dermoscopic features in neoplasms in SoC.

Diagnosis of Melanonychia

Melanonychia has many causes and can involve one or several fingernails or toenails, and may occur at any age. Dermoscopy is used routinely in the evaluation of a pigmented nail. If pigmentation is caused by melanin produced by nail matrix, identify whether the pigmentation is caused by an activation or proliferation of nail melanocytes. When melanocytic proliferation is suspected, biopsy with histopathologic examination is the gold standard for diagnosis and is recommended when a longitudinal melanonychia occurs in an adult and is localized in a single digit, in the absence of local or systemic causes that may explain its onset.

Dermoscopy of the Nail Unit

Nail dermoscopy (onychoscopy) is being used for a more accurate diagnosis of all nail disorders and has become a routine diagnostic instrument. In daily practice, nail signs can be magnified, and dermoscopy may confirm the clinical diagnosis and guides in management of nail diseases and treatments, permitting a better visualization of symptoms. Onychoscopy is used by the experts in almost all nail diseases. It can be performed dry or with ultrasound gel in order to make the stratum corneum translucent, depending on which part of the nail unit has to be evaluated.

Cutaneous and Mucosal Melanomas of Uncommon Sites: Where Do We Stand Now?

Melanomas arising at uncommon sites include a group of lesions related to unusual localizations in specific ethnic groups. The rarity of the disease often represents a limit to the participation of patients in specific trials. However, this peculiar genetic scenario has important therapeutic implications regarding new oncologic therapies. The aim of this article is to review the clinical features, somatic alterations and therapeutic options for melanomas of uncommon sites. They can be classified as cutaneous and mucosal lesions affecting the nail apparatus, palms/soles, oral mucosa, genital area and scalp. The prognosis may be worse compared to melanomas of other districts, and a prompt diagnosis may dramatically influence the outcome. Dermatologists and oncologists should therefore distinguish this melanoma subgroup in terms of surgical intervention and medical treatment. Due to the lack of mutations in genes usually found in cutaneous melanomas, the discovery of novel targets is required to develop new strategies and to change the prognosis of non-responders or wild-type patients.

Subungual Melanocytic Lesions: Key Clinical and Pathologic Concepts and Biopsy Techniques

Both dermatologists and pathologists sometimes find daunting the evaluation of melanonychia (especially subungual melanocytic lesions) because of the fear of performing nail surgery due to the risk of dystrophy, difficulties processing and interpreting nail biopsy specimens, and a general lack of experience in the field. Nevertheless, mastery of nail biopsy techniques, correct processing and orientation of specimens, and familiarity with the histologic particularities of the nail apparatus can attenuate the undoubted complexity and facilitate the tasks involved. Longitudinal excision is the biopsy technique that ensures the simplest histologic interpretation, and it is associated with a low risk of nail dystrophy when performed correctly. Clinical and epidemiological data are crucial. Subungual melanoma in childhood, for instance, is very rare and even lesions with atypical clinical and/or histologic features are probably benign. The presence of suprabasal melanocytes and other findings that would suggest malignancy at other sites are considered normal in the nail apparatus. Subungual melanoma shows a lentiginous pattern in the early stages of disease, and detection of an inflammatory infiltrate accompanying atypical lentiginous subungual lesions would appear to be one of the first diagnostic findings.

Dermatophytic melanonychia: A case series of an increasing disease

BACKGROUND

Melanonychia refers to brown-black colour pigmentation due to melanin or not-melanin deposition in the nail plate. Onychoscopy allows to distinguish if the pigmentation is due by melanin or not. The main causes of non-melanic pigmentation are subungual haematoma and pigmented onychomycosis. Fungal melanonychia (FM) is rare and may present as diffuse or longitudinal pigmentation. Differential diagnosis includes melanic activation, such as ethnic-type nail pigmentation or frictional melanonychia, but also versus melanic proliferation, such as nevus or nail melanoma. Fungal melanonychia can be due to a colonisation by fungi with black variant or by melanin activation due to inflammation of fungal invasion.

OBJECTIVES

The aim of paper is to increase clinical and dermoscopic knowledge of this increasingly frequent disease.

METHODS

In this retrospective observational study, twenty patients with dermatophytic melanonychia were collected, with available clinical and dermoscopic pictures. The diagnosis of dermatophytic melanonychia was made based on clinical manifestation and mycological examination. KOH smear was performed in all cases. For each patient, clinical data included: age, gender, type of melanonychia and involved fingers.

RESULTS

This study aimed to show increased incidence of dermatophytic melanonychia and its correct management. In addition, we reviewed our collected cases and described the clinical and dermoscopic features of dermatophytic melanonychia.

CONCLUSIONS

The results of this study showed that physicians should keep in mind the diagnosis of this increasing disease, and that it cannot be performed relying only on clinical grounds. We would like to highlight the importance of tools as KOH examination, culture and dermoscopy.

Clinical and Onychoscopic Features of Benign and Malignant Conditions in Longitudinal Melanonychia in the Thai Population: A Comparative Analysis

Background

Longitudinal melanonychia can arise from many underlying conditions, both benign and malignant. Practitioners tend to be reluctant to perform a biopsy of this condition due to procedure-related pain and the possibility of permanent nail dystrophy. Onychoscopy has become a useful tool to provide a provisional diagnosis and assist in deciding on a nail biopsy.

Objective

To investigate and differentiate the clinical and onychoscopic features of subungual melanoma (SUM)/subungual melanoma in situ (SMIS) and other benign melanocytic conditions (BM).

Materials and Methods

In this cross-sectional study, a total of 32 cases of longitudinal melanonychia were examined, and baseline characteristics were recorded. Onychoscopic pictures were taken by handheld dermoscopy with 10x and 50x magnification. A biopsy was then performed in each case, and a pathological diagnosis was obtained.

Results

Of the 32 cases, 6 were diagnosed with SMIS and 26 with BM (21 simple lentigines, 5 junctional nevi). The median age was significantly higher among the SMIS group (56 vs 31 years) (p = 0.034). Regarding onychoscopic findings, cases with SMIS were significantly associated with a greater band width percentage (p = 0.014), multicolor presentation (p = 0.005), the presence of granular pigmentation (p = 0.034), and micro-Hutchinson’s sign (p = 0.015). In addition, subungual hyperkeratosis, a newly recognized onychoscopic feature, was more significantly associated with SMIS in comparison to BM (p = 0.002).

Conclusion

Onychoscopy provides useful information to aid in the differential diagnosis of longitudinal melanonychia. From our study, onychoscopy can be utilized to assist in making a decision whether to perform a biopsy in patients with longitudinal melanonychia suspicious of malignant melanocytic conditions.

Developing a predictive model for distinguishing invasive nail unit melanoma from nail unit melanoma in situ

BACKGROUND

Clinical information that distinguishes invasive nail unit melanoma from nail unit melanoma in situ before surgery would aid physicians in the decision-making process and estimating prognosis. However, limited information is available on the detailed demographic and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ for differential diagnosis.

OBJECTIVE

This study aimed to investigate the demographic data and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ and establish a predictive model for differentiating these two forms of nail unit melanoma.

METHODS

A retrospective observational study of ninety-seven patients diagnosed with nail unit melanoma (59 in situ and 38 invasive cases) in four healthcare centres in South Korea (three tertiary referral hospitals and one second referral hospital) from March 2014 to December 2019.

RESULTS

A multivariable analysis revealed that ulcer (odds ratio = 21.6, confidence interval = 2.1-219.8, P = 0.009), total melanonychia (odds ratio = 17.6, confidence interval = 3.0-104.0, P = 0.002), nail plate destruction (odds ratio = 10.9, confidence interval = 2.0-59.4, P = 0.006) and polychromia (odds ratio = 5.3, confidence interval = 1.36-20.57, P = 0.016) were distinctive dermoscopic features of invasive nail unit melanoma. A predictive model with scores ranging from 0 to 6 points demonstrated a reliable diagnostic value (C-statistic = 0.902) in differentiating invasive nail unit melanoma from nail unit melanoma in situ.

CONCLUSIONS

Invasive nail unit melanoma and nail unit melanoma in situ have different dermoscopic features. A predictive model based on morphologic dermoscopic features could aid in differentiating invasive nail unit melanoma from nail unit melanoma in situ.

Dermoscopic diagnosis of subungual hematoma: new observations

Introduction

There are very few studies focusing on the dermoscopic features of subungual hematoma which is one of the major imitators of subungual melanoma.

Aim

To identify the dermoscopic findings of subungual hematoma, which will facilitate the diagnostic process by reducing the use of more invasive diagnostic methods like nail avulsion or biopsy.

Material and methods

In this study, clinical and dermoscopic findings of the cases were reviewed. The diagnosis of subungual hematoma was confirmed by observing progression of the colour change to the distal edge of the nail plate in all the cases.

Results

A total of 47 subungual hematomas were enrolled in the study. The most common colour was purple-black (53%). Blue-white colour was observed in 12 (26%) lesions. 9 (19%) lesions showed granular leukonychia. All of the lesions had a homogenous pattern. In 25 (53%) lesions, a globular pattern was observed. 14 (30%) lesions showed a streaks pattern. Peripheral fading and periungual haemorrhage were present in 14 (30%) and 9 (9%) lesions, respectively.

Conclusions

We detected two new findings which have not been described previously for subungual hematoma: the first one is “blue-white colour” which is known as an important clue to melanoma. The second one is granular leukonychia localized on the hematoma. We suggest that in any case of the nail discoloration, a thorough dermoscopic examination should be performed. Moreover, progression of the colour change to the distal edge should be observed to ensure that a possible melanoma is not overlooked.

Acral lentiginous melanoma: Basic facts, biological characteristics and research perspectives of an understudied disease

Acral lentiginous melanoma is a histological subtype of cutaneous melanoma that occurs in the glabrous skin of the palms, soles and the nail unit. Although in some countries, particularly in Latin America, Africa and Asia, it represents the most frequently diagnosed subtype of the disease, it only represents a small proportion of melanoma cases in European‐descent populations, which is partially why it has not been studied to the same extent as other forms of melanoma. As a result, its unique genomic drivers remain comparatively poorly explored, as well as its causes, with current evidence supporting a UV‐independent path to tumorigenesis. In this review, we discuss current knowledge of the aetiology and diagnostic criteria of acral lentiginous melanoma, as well as its epidemiological and histopathological characteristics. We also describe what is known about the genomic landscape of this disease and review the available biological models to explore potential therapeutic targets.

Oral and nail pigmentations: a useful parallelism for the clinician

Oral (OP) and nail (NP) pigmentations may occur simultaneously in physiological or pathological conditions, and may be a sign of underlying syndromic conditions that necessitate further investigation and treatment. Interestingly, the nail unit and oral cavity show a clinical parallelism that may help the clinician to conduct a correct examination and reach a prompt diagnosis. Both OP and NP can manifest clinically with focal or diffuse involvement and are due to external factors (exogenous pigmentation, drug-induced pigmentation) or endogenous factors (racial pigmentation, post-inflammatory pigmentation, nevi, genetic conditions and other disorders). The most concerning differential diagnosis is melanoma. Here we report the pathogenetic basis of OP and NP, together with the description of similar clinical features. To the best of our knowledge this is the first paper to summarize and describe the causes of pigmentation of both the oral cavity and the nail unit.

Macroscopic and dermoscopic evaluation used to differentiate subungual haemorrhage from melanocytic lesions

INTRODUCTION Subungual haemorrhage describes blood located between the nail matrix and nail plate caused by trauma. Lack of recalled trauma and long duration of nail pigmentation results in specialist referrals to rule out malignant pathology. AIM This report aims to describe the macroscopic and dermoscopic characteristics of subungual haemorrhage and to highlight its clinical differentiation from melanocytic lesions. METHODS Ninety-eight nails were assessed. Pigmentation in fifty-nine was due to subungual haemorrhage and was melanocytic in the remainder (identified by a longitudinal pigmented band). RESULTS Pigmentation in subungual haemorrhage had a clear proximal margin (73%) and the dermoscopic pattern was homogenous (97%), globular (78%) or streaky (34%). Features included peripheral fading (68%) and periungual haemorrhage (5%). Malignancy could be excluded in these cases by careful clinical evaluation. DISCUSSION A combination of macroscopic and dermoscopic characteristics help make a confident diagnosis of subungual haemorrhage. A two-stage process can aid clinical diagnosis by looking for known features of subungual haemorrhage and identifying absence of malignant features.

Should we biopsy melanonychia striata in Asian children? A retrospective observational study

BACKGROUND AND OBJECTIVES

Melanonychia striata is common in children of darker-skinned Asian races, while subungual melanoma is extremely rare and it is difficult to make a diagnosis clinically. However, performing nail unit biopsies in children is particularly challenging and can result in permanent nail dystrophy. The aim of this study was to review the clinical and histologic characteristics of melanonychia striata in pediatric patients of Asian descent to aid in the clinical decision regarding nail biopsy.

METHODS

Sixty-two pediatric patients presenting with melanonychia striata involving single or multiple nails at two tertiary pediatric dermatology clinics in Singapore between 2005 and 2015 were reviewed. Clinical and histopathological data were analyzed, including age at onset, age at presentation, location, color, width, presence of Hutchinson's sign, pseudo-Hutchinson's sign, nail dystrophy, length of follow-up, and clinical evolution. Histopathological assessment was performed by three senior dermatopathologists independently for cases that underwent a nail biopsy.

RESULTS

No cases of subungual melanoma were detected in our series. Solitary melanonychia of the thumbnail with a single uniform color was the most common presentation. Pseudo-Hutchinson's sign was commonly observed. Consensus in histological diagnosis emerged amongst all three dermatopathologists in only half of the cases biopsied.

CONCLUSION

The occurrence of melanoma in Asian children presenting with melanonychia is extremely rare. We recommend clinical follow-up and anticipatory guidance for these patients and nail unit biopsy only in the presence of high-risk clinical features.

Assessment of a Predictive Scoring Model for Dermoscopy of Subungual Melanoma In Situ

Importance

Subungual melanoma in situ (SMIS) is a malignant neoplasm that requires early diagnosis and complete surgical excision; however, little is known about the usefulness of the detailed dermoscopic features of longitudinal melanonychia (LM) to predict the diagnosis of SMIS.

Objectives

To investigate the characteristic dermoscopic findings of SMIS and to establish a predictive scoring model for the diagnosis of SMIS in patients with adult-onset LM affecting a single digit.

Design, Setting, and Participants

A cohort study of 19 patients with biopsy-proven SMIS and 26 patients with benign LM diagnosed in a tertiary referral hospital in Seoul, South Korea, from September 1, 2013, to July 31, 2017.

Main Outcomes and Measures

Patient demographics, frequency of specific dermoscopic findings, and a predictive scoring model.

Results

Of the total 45 patients with pigmented nails, the 19 patients with SMIS included 14 women and had a mean (SD) age of 52.0 (14.4) years, and the 26 patients with benign LM included 18 women and had a mean (SD) age of 48.1 (13.2) years. Asymmetry (odds ratio [OR], 34.00; 95% CI, 3.88-297.70), border fading (OR, 9.33; 95% CI, 2.37-36.70), multicolor (OR, 11.59; 95% CI, 2.21-60.89), width of the pigmentation of at least 3 mm (OR, 5.31; 95% CI, 1.01-28.07), and presence of the Hutchinson sign (OR, 18.18; 95% CI, 2.02-163.52) were features of LM that were significantly associated with SMIS. A predictive scoring model incorporating these dermoscopic features of SMIS was assessed. The model, ranging from 0 to 8 points, showed a reliable diagnostic value (the receiver operating characteristic curve had an area under the curve [C statistic] of 0.91) in differentiating SMIS from benign LM at a cutoff value of 3, with a sensitivity of 89% and a specificity of 62%.

Conclusions and Relevance

This study suggests characteristic dermoscopic features for SMIS. A predictive scoring model based on these morphologic features may help differentiate SMIS from benign LM.

Dermoscopy of Melanoma and Non-melanoma Skin Cancers

Dermoscopy is a widely used non-invasive technique for diagnosing skin tumors. In melanocytic tumors, e.g., melanoma and basal cell carcinoma (BCC), the effectiveness of dermoscopic examination has been fully established over the past two decades. Moreover, dermoscopy has been used to diagnose non-melanocytic tumors. Here, we review novel findings from recent reports concerning dermoscopy of melanoma and non-melanoma skin cancers including BCC, sebaceous carcinoma, actinic keratosis, Bowen's disease, squamous cell carcinoma (SCC), Merkel cell carcinoma (MCC), extramammary Paget's disease (EMPD), and angiosarcoma.

The color of skin: black diseases of the skin, nails, and mucosa

Gradations in skin color are a consequence of differing amounts of melanin and their varying distribution. Although many darkly pigmented skin lesions are melanocytic and can be attributed to melanin content, the color of a black lesion can also be due to blood, necrotic tissue, or exogenous pigment. The source, pattern, and distribution of the color in black lesions usually offer important insight into its etiology. This contribution reviews conditions that can take on a black color, discussing the cause of the hue and any additional impact sun exposure may have.

Use of Nail Dermoscopy in the Management of Melanonychia: Review

The term melanonychia describes a black-brown-gray pigmentation of the nail plate that, in most cases, appears as a longitudinal band. Melanonychia can be observed at any age, affecting one digit or several digits, in both fingernails and toenails. Its causes can be difficult to differentiate clinically and depend on the number of bands and on their color, edge, and width. For this reason, especially in adults and when the pigmentation is localized in one single digit, biopsy and histopathological examination still represent the gold standard for a definitive diagnosis. Dermoscopy should be used routinely in the evaluation of a pigmented nail, as it provides important information for the management of melanonychia and can help avoid unnecessary nail biopsies. In cases of melanonychia it is important to establish whether the pigment is melanin or not and to determine whether the pigmentation of melanin is due to activation or proliferation and whether it is benign or malignant.

Mystery behind labial and oral melanotic macules: Clinical, dermoscopic and pathological aspects of Laugier-Hunziker syndrome

Labial and oral melanotic macules are commonly encountered in a broad range of conditions ranging from physiologic pigmentation to a sign of an underlying life-threatening disease. Although Laugier-Hunziker syndrome (LHS) shares some features of labial and oral pigmentation with a variety of conditions, it is a benign and acquired condition, frequently associated with longitudinal melanonychia. Herein, the demographic, clinical, dermoscopic, and pathological aspects of LHS were reviewed comprehensively. The important differential diagnoses of mucocutaneous and nail pigmentation are provided. An accurate diagnosis is crucial to design a reasonable medical strategy, including management options, malignant transformation surveillance, and psychological support. It is important that clinicians conduct long-term follow-up and surveillance due to the potential risks of malignant transformation and local severe complications in some conditions.

Dermatoscopy of Neoplastic Skin Lesions: Recent Advances, Updates, and Revisions

OPINION STATEMENT

Dermatoscopy (dermoscopy) improves the diagnosis of benign and malignant cutaneous neoplasms in comparison with examination with the unaided eye and should be used routinely for all pigmented and non-pigmented cutaneous neoplasms. It is especially useful for the early stage of melanoma when melanoma-specific criteria are invisible to the unaided eye. Preselection by the unaided eye is therefore not recommended. The increased availability of polarized dermatoscopes, and the extended use of dermatoscopy in non-pigmented lesions led to the discovery of new criteria, and we recommend that lesions should be examined with polarized and non-polarized dermatoscopy. The "chaos and clues algorithm" is a good starting point for beginners because it is easy to use, accurate, and it works for all types of pigmented lesions not only for those melanocytic. Physicians, who use dermatoscopy routinely, should be aware of new clues for acral melanomas, nail matrix melanomas, melanoma in situ, and nodular melanoma. Dermatoscopy should also be used to distinguish between different subtypes of basal cell carcinoma and to discriminate highly from poorly differentiated squamous cell carcinomas to optimize therapy and management of non-melanoma skin cancer. One of the most exciting areas of research is the use of dermatoscopic images for machine learning and automated diagnosis. Convolutional neural networks trained with dermatoscopic images are able to diagnose pigmented lesions with the same accuracy as human experts. We humans should not be afraid of this new and exciting development because it will most likely lead to a peaceful and fruitful coexistence of human experts and decision support systems.

Dermoscopy in the Evaluation of Nail Disorders

Nail dermoscopy was initially used only in the assessment of nail pigmentation, but now it is widely utilized for the evaluation of many nail disorders. In daily practice, dermoscopy may confirm clinical diagnoses and guides in the management of nail diseases and treatments, permitting a better visualization of symptoms. Dry dermoscopy is required for evaluation of the nail plate surface, while gel as an interface is necessary for assessment of nail pigmentation and onycholysis, as well as for the evaluation of the distal nail margin. In this review, we describe the dermoscopic features of the most important nail disorders, looking at the different areas of the nail. Dermatoscopic changes that usually accompany specific nail diseases are also reviewed.