Mortality trend of cutaneous melanoma in Montenegro from 1990-2018.

OBJECTIVE: Every year, melanoma claims over 20,000 lives in Europe. In Montenegro, as in Europe, numerous campaigns have been initiated to raise public awareness about the importance of melanoma prevention and its early detection. Thus, accompanying current diagnostic and therapeutic protocols, new methods of melanoma diagnosis and treatment have been implemented. Studying the trend enables the identification of the groups most burdened by mortality and assesses whether there has been a change in trends based on interventions aiming to reduce mortality. The objective of this study is to evaluate the mortality trend from cutaneous melanoma in Montenegro for the period 1990-2018. MATERIALS AND METHODS: We have utilized national data on the causes of death from melanoma, code 179 from the ninth and C43 from the tenth revision of the International Classification of Diseases, categorized by gender and age groups. The study utilized various regression techniques, including Joinpoint regression in the Joinpoint Program, Poisson regression, and linear regression in the SPSS 26th Program, to describe the trend. RESULTS: In Montenegro, during the period from 1990 to 2018, a total of 281 individuals died (51.6% male and 48.4% female). This ranks as the 13th leading cancer in terms of mortality among all cancers. The average age-standardized rate was 1.1 deaths per 100,000 (1.2 for males and 1.0 for females).  The number of death cases has been increasing on average by 3.3% annually [average annual percentage change (AAPC) (95% CI) = 3.3 (1.7-4.9); p<0.001] on an overall level and by 5.4% annually among males [AAPC (95% CI) = 5.4 (3.6-7.3); p<0.001] due to the rises in the age groups 55-64 years and 65-74 years with an average annual percent change of respectively 3.2% [AAPC (95% CI) = 3.2 (0.8-5.8); p=0.012] and 5.4% [AAPC (95% CI) = 5.4 (2.7-8.1); p<0.001] overall level, and 4.8% [AAPC (95% CI) = 4.8 (2.4-7.3); p<0.001] and 7.5% [AAPC (95% CI) = 7.5 (4.9-10.2); p<0.001] among males. For females, an increase of 1.1% was recorded, which was not statistically significant [AAPC (95% CI) = 1.1 (-0.8-3.0); p=0.255]. Furthermore, there was a noted increase in the rates at an overall level [ß (95% CI) = 0.027 (0.008-0.046); p=0.007] and in the age group 65-74 years [ß (95% CI) = 0.249 (0.090-0.407); p=0.003], as well as among males at an overall level [ß (95% CI) = 0.052 (0.025-0.079); p<0.001] and for age groups 45-54 years [ß (95% CI) = 0.102 (0.011-0.193); p=0.030] and 65-74 [ß (95% CI) = 0.410 (0.144-0.676); p=0.004]. In contrast, the rates for females remained constant. The three age groups most burdened by melanoma skin cancer mortality are 65-74 years (23.5%), 55-64 years (21.7%) and 75-84 years  (19.2%). CONCLUSIONS: The results of regression analyses indicate a significant rise in both the number of death cases and mortality rates overall, specifically among males in Montenegro. In females, however, the increase in the number of death cases and rates is not statistically significant. Preventive campaign activities should be redirected towards the most vulnerable groups in terms of mortality, namely males and the elderly population.

Common skin cancers and their association with other non-cutaneous primary malignancies: a review of the literature.

It has long been recognized that a history of skin cancer puts one at risk for additional primary skin cancers. However, more variable data exists for the risk of developing a non-cutaneous primary cancer following a diagnosis of skin cancer. The data are most variable for Basal Cell Carcinoma (BCC), the most common and least aggressive type of skin cancer. While early studies imply that BCC does not impart a larger risk of other primary non-cutaneous cancers, more recent studies with larger populations suggest otherwise. The cancers most significantly associated with BCC are lip, oropharyngeal, and salivary gland cancer. There is also burgeoning evidence to suggest a link between BCC and prostate, breast, and colorectal cancer, but more data are needed to draw a concrete conclusion. Squamous Cell Carcinoma (SCC), the second most common type of skin cancer, has a slightly more defined risk to other non-cutaneous primary malignancies. There is a notable link between SCC and non-Hodgkin's lymphoma (NHL), possibly due to immunosuppression. There is also an increased risk of other cancers derived from squamous epithelium following SCC, including oropharyngeal, lip, and salivary gland cancer. Some studies also suggest an increased risk of respiratory tract cancer following SCC, possibly due to shared risk factors. Melanoma, a more severe type of skin cancer, shows a well-defined risk of additional primary non-cutaneous malignancies. The most significant of these risks include NHL, thyroid cancer, prostate cancer, and breast cancer along with a host of other cancers. Each of these three main skin cancer types has a profile of genetic mutations that have also been linked to non-cutaneous malignancies. In this review, we discuss a selection of these genes to highlight the complex interplay between different tumorigenesis processes.

Skin cancers are the most frequent cancers in fair-skinned populations, but we can prevent them.

Cancers of the skin are the most commonly occurring cancers in humans. In fair-skinned populations, up to 95% of keratinocyte skin cancers and 70-95% of cutaneous melanomas are caused by ultraviolet radiation and are thus theoretically preventable. Currently, however, there is no comprehensive global advice on practical steps to be taken to reduce the toll of skin cancer. To address this gap, an expert working group comprising clinicians and researchers from Africa, America, Asia, Australia, and Europe, together with learned societies (European Association of Dermato-Oncology, Euromelanoma, Euroskin, European Union of Medical Specialists, and the Melanoma World Society) reviewed the extant evidence and issued the following evidence-based recommendations for photoprotection as a strategy to prevent skin cancer. Fair skinned people, especially children, should minimise their exposure to ultraviolet radiation, and are advised to use protective measures when the UV index is forecast to reach 3 or higher. Protective measures include a combination of seeking shade, physical protection (e.g. clothing, hat, sunglasses), and applying broad-spectrum, SPF 30 + sunscreens to uncovered skin. Intentional exposure to solar ultraviolet radiation for the purpose of sunbathing and tanning is considered an unhealthy behaviour and should be avoided. Similarly, use of solaria and other artificial sources of ultraviolet radiation to encourage tanning should be strongly discouraged, through regulation if necessary. Primary prevention of skin cancer has a positive return on investment. We encourage policymakers to communicate these messages to the general public and promote their wider implementation.

Aggregation of melanoma tumour site within Western Australian families.

BACKGROUND: Evidence is emerging that melanoma has distinct aetiologic pathways and subtypes, characterized by factors like anatomic site of the tumour. To explore genetic influences on anatomic subtypes, we examined the extent to which melanomas in first-degree relatives shared the same body site of occurrence. METHODS: Population-level linked data was used to identify the study population of over 1.5 million individuals born in Western Australia between 1945 and 2014, and their first-degree relatives. There were 1009 pairs of invasive tumours from 677 family pairs, each categorised by anatomic site. Greater than expected representation of site-concordant pairs would suggest the presence of genetic factors that predispose individuals to site-specific melanoma. RESULTS: Comparing observed versus expected totals, we observed a modest increase in site concordance for invasive head/neck and truncal tumours (P=0.02). A corresponding analysis including in situ tumours showed a similar concordance (P=0.05). No further evidence of concordance was observed when stratified by sex. CONCLUSION: In conclusion, modest evidence of aggregation was observed but with inconsistent patterns between sites. Results suggest that further investigation into the familial aggregation of melanoma by tumour site is warranted, with the inclusion of genetic data in order to disentangle the relative contributions of genetic and environmental factors.

Stressful life events and the occurrence of skin cancer.

OBJECTIVE: It is widely acknowledged that emotional states can influence skin conditions, yet limited research has delved into the impact of stress on skin cancer development. This retrospective study sought to expand the perspective on skin cancer risk factors by investigating the complex relationship between stressful life events and the incidence of skin cancer. METHODS: The sample included 268 individuals followed-up in a dermatological clinic, in three groups: Patients who had previously been diagnosed with cutaneous melanoma and are currently in remission (32%), those who had been diagnosed with non-melanoma skin cancer (30%), and a control group who are at risk for skin cancer (38%). Participants filled in questionnaires regarding childhood and adulthood life events, and loss and gain of resources following their subjectively most stressful event in adulthood. Multinomial logistic regression was used to examine the associations of life events with skin cancer occurrence, and mediating and moderating effects of resource loss/gain. RESULTS: Adverse childhood experiences were associated with melanoma occurrence, with the melanoma group reporting significantly more such experiences compared to the control group (p < 0.001). Resource loss from subjectively significant stressful life events in adulthood partially mediated the association between adverse childhood experiences and melanoma incidence. CONCLUSIONS: The findings suggest that there may be intricate connections between stress, life events, adaptation to change, and skin cancer, which future research may further unravel. This study underscores the need for a more comprehensive approach to stress management, coping strategies development, and skin cancer prevention in healthcare settings.

Incidence Rates and Outcomes of Nodular and Superficial Spreading Melanoma along the Rural-Urban Continuum in Kentucky and Their Relationship to Provider Care Access.

OBJECTIVES: This study compared incidence rates, stage at presentation, and cause-specific mortality of nodular and superficial spreading melanoma along the rural-urban continuum in Kentucky. We compared resulting patterns in our data with sample demographic and other potential factors, including population by county and primary care provider rate. METHODS: Retrospective patient data were extracted from the Surveillance, Epidemiology, and End Results database from 2010 through 2017. These data were supplemented by environmental, demographic, and socioeconomic data derived from publicly accessible databases. Correlation and χ2 analyses were used to test for significant differences in outcome variables by US Department of Agriculture Rural-Urban Continuum Code (RUCC) categories and other potential predictor variables. RESULTS: Incidence rates by Kentucky county were not associated with RUCC or population; likewise, there was no relationship between stage at presentation and RUCC category. There was, however, a highly significant association between cause-specific mortality and RUCC; patients from rural areas were significantly more likely to die from melanoma than those in urban areas. This overall difference was due to differences in mortality for superficial spreading melanoma. CONCLUSIONS: Our results suggest that a disparity in patients' ability or tendency to access primary care and/or specialist providers postdiagnosis may be critical factors in determining the ultimate outcome of a melanoma diagnosis. Further studies should explore the availability of dermatologists and/or treatment options for melanoma in rural areas. Our data also provide additional support for inclusion of melanoma subtype in the American Joint Committee on Cancer guidelines.

Influence of Anatomic Locations of T1b Melanomas and Patient Age on Outcomes.

BACKGROUND: There are no guidelines on when to more strongly recommend sentinel lymph node biopsy (SLNB) for T1b melanomas. OBJECTIVE: To examine whether anatomic locations of T1b melanomas and patient age influence metastases. METHODS: We conducted a retrospective study using data from two hospitals in Los Angeles County from January 2010 through January 2020. RESULTS: Out of 620 patients with primary melanomas, 566 melanomas were staged based on the American Joint Committee on Cancer 8th edition melanoma staging. Forty-one were T1b, of which 13 were located on the face/ear/scalp and 28 were located elsewhere. T1b melanomas located on the face/ear/scalp had an increased risk of lymph node or distant metastasis compared with other anatomic sites (31% vs 3.6%, P=0.028). For all melanomas, the risk of lymph node or distant metastasis decreased with age of 64 years or greater (P<0.001 and P=0.034). For T1b melanomas, the risk of distant metastasis increased with increasing age (P=0.047). LIMITATIONS: Data were from a single county.  Conclusion: T1b melanomas of the face/ear/scalp demonstrated a higher risk of lymph node or distant metastasis and may help guide the recommendation of SLNB, imaging, and surveillance. Younger patients may be more strongly considered for SLNB and older patients with T1b melanomas may warrant imaging.  J Drugs Dermatol. 2024;23(5):306-310. doi:10.36849/JDD.7667.

Association between air pollution and skin cutaneous melanoma: A Mendelian randomization study.

There has been a consistent and notable increase in the global prevalence of skin cutaneous melanoma (SKCM). Although genetic factors are closely associated with the occurrence and development of melanoma, the potential influence of environmental factors cannot be overlooked. The existing literature lacks a definitive consensus on the correlation between air pollution and the incidence rate of SKCM. This study seeks to investigate the causal relationship between air pollution, specifically focusing on particulate matter (PM) 2.5, PM2.5-10, PM10, and nitrogen oxides, and the risk of SKCM. A 2-sample Mendelian randomization (MR) method was applied, utilizing extensive publicly accessible genome-wide association studies summary datasets within European populations. The primary analytical method employed was the inverse variance weighted method. Supplementary methods, including the weighted median model, MR-Egger, simple model, and weighted model, were chosen to ensure robust analysis. Heterogeneity assessment was conducted using Cochran's Q test. To identify potential pleiotropy, both MR-Egger regression and the MR-PRESSO global test were employed. Additionally, a sensitivity analysis was performed using the leave-one-out method. The analysis revealed no statistically significant association between air pollution and SKCM risk, with specific findings as follows: PM2.5 (P = .485), PM2.5-10 (P = .535), PM10 (P = .136), and nitrogen oxides (P = .745). While some results exhibited heterogeneity, all findings demonstrated an absence of pleiotropy. This study did not find substantive evidence supporting a causal relationship between air pollution and the risk of SKCM within European populations. The comprehensive MR analysis, encompassing various pollutants, suggests that environmental factors such as air pollution may not be significant contributors to the development of SKCM.

[Screening for cutaneous melanoma: little impact, major challenges]. / Dépistage du mélanome : peu d'impact, beaucoup de défis.

Routine screening for melanoma has never been shown to be effective. Here, we revisit this debate and the preconceived notion that the increased detection of early-stage melanoma should necessarily be followed within the same population by a reduction in the incidence of advanced stages, which is not supported by any evidence. The issue of overdiagnosis, which has been debated for several decades, is discussed in the light of screening practices. We illustrate with two of its common motives, why this practice is ineffective. Finally, we suggest that the risk of overdiagnosis has probably reached its climax over the last two decades, as the increasing sensitivity of skin-imaging tools has not been followed by a refinement of histopathologic diagnostic criteria.

Le dépistage systématique du mélanome n'a jamais fait la preuve de son efficacité. Nous rediscutons ici de cette question en revenant sur l'idée reçue que le dépistage accru des stades précoces de mélanome au sein d'une population devrait engendrer une diminution des formes avancées de la maladie, ce qui ne se vérifie pas dans les faits. La question débattue depuis plusieurs décennies du surdiagnostic est également discutée à la lumière des pratiques de dépistage. Nous illustrons par deux motifs fréquents de dépistage pourquoi cette pratique est inefficace. Nous suggérons que le risque de surdiagnostic a atteint son paroxysme au cours des deux dernières décennies dans la mesure où la sensibilité croissante des outils d'imagerie cutanée n'a pas été suivie d'un affinement des critères diagnostiques histopathologiques.

The influence of rurality on melanoma diagnosis in Indiana: A retrospective cohort study.

BACKGROUND: Research from across the United States has shown that rurality is associated with worse melanoma outcomes. In Indiana, nearly a quarter of all residents live in rural counties and an estimated 2180 cases of melanoma will be diagnosed in 2023. AIMS: This study examines how geographical location affects the stage of melanoma diagnosis in Indiana, aiming to identify and address rural health disparities to ultimately ensure equitable care. METHODS AND RESULTS: Demographics and disease characteristics of patients diagnosed with melanoma at Indiana University Health from January 2017 to September 2022 were compared using Students t-tests, Wilcoxon tests, chi-squared or Fisher's exact tests. Patients from rural areas presented with more pathological stage T3 melanomas (15.0% vs. 3.5%, p < 0.001) in contrast to their urban counterparts. Additionally, rural patients presented with fewer clinical stage I melanomas (80.8% vs. 89.3%) and more clinical stage II melanomas (19.2% vs. 8.1%), compared to urban patients, with no stage III (p = 0.028). Concerningly, a significantly higher percentage of the rural group (40.7%) had a personal history of BCC compared to the urban group (22.6%) (p = 0.005) and fewer rural patients (78.0%) compared to urban patients (89.4%) received surgical treatment (p = 0.016). CONCLUSION: Patients from rural counties in Indiana have higher pathological and clinical stage melanoma at diagnosis compared to patients from urban counties. Additionally fewer rural patients receive surgical treatment and may be at higher risk of developing subsequent melanomas.

Uveal melanoma incidence and survival analysis in Portugal between 2013 and 2022.

PURPOSE: This study aims to provide a comprehensive overview of the clinical characteristics and epidemiology of uveal melanoma (UM) in the Portuguese population, evaluated at the National Reference Centre (NRC). METHODS: A prospective observational study was conducted, involving patients consecutively diagnosed with UM at the Portuguese NRC between July 2013 and December 2022. The study collected data on demographic and tumour characteristics, clinical staging according to the American Joint Committee on Cancer (AJCC), treatment approaches, local disease control, patient survival, and the occurrence of distant metastases. RESULTS: The study included a total of 316 patients, 53.8% female. The mean age at diagnosis was 61.8±14.2 years, and 75.0% of patients presented with symptoms. The mean annual age-adjusted incidence of uveal melanoma in Portugal between 2014 and 2022 was 2.4 cases per million (95% confidence interval [CI]: 2.1-2.8). For choroidal/ciliary body tumours, the overall cumulative survival and distant metastases-free survival (DMFS) rates at 5 years were 84.9% (95% CI: 78.7-91.1) and 79.4% (95%CI: 72.8-86.0), respectively. Notably, higher AJCC stages at presentation, the need for enucleation, and increased tumour thickness were associated with lower DSS and DMFS rates. CONCLUSION: This study represents the most extensive analysis of UM epidemiology within the Portuguese population. The findings underscore the importance of early diagnosis and treatment in UM, as lower AJCC stages and smaller tumour thickness at diagnosis correlate with improved DSS and DMFS.

Vitamin D and Cutaneous Melanoma Risk: An Umbrella Review of Systematic Reviews and Meta-Analyses.

Background: Vitamin D (VitD) properties can impact cancer cells. Despite the documented link between VitD levels and prevalence of several cancer types, conflicting findings have been reported for cutaneous melanoma (CM). Objective: This overview aims to compile the evidence from existing systematic reviews and meta-analyses, emphasizing the relationships between VitD serum levels, intake, receptor (VDR) gene polymorphisms, and CM risk. Methods: A literature search in electronic databases was conducted, based on certain inclusion criteria. Results: Twenty-one studies were included. Conflicting evidence between high VitD serum levels, dietary/supplementary intake, and CM risk is highlighted. VDR polymorphisms may play a role in the intricate CM pathogenesis. Also, high serum levels of VitD are associated with improved CM prognosis. Conclusions: This overview showed that the impact of VitD on CM is not clear, and thus further research is suggested to explore its true effect size on CM risk.

Skin Cancer Risk of Narrow-Band UV-B (TL-01) Phototherapy: A Multi-Center Registry Study with 4,815 Patients.

Narrow-band TL-01 ultraviolet B phototherapy (TL-01) is an effective and widely used treatment for many skin diseases. The purpose of the investigation was to assess the risk of skin cancers in patients treated with TL-01 phototherapy who have not received any other phototherapy modalities. This cohort study included 4,815 TL-01 treated patients in Finland with psoriasis or atopic dermatitis. Clinical information was collected from the hospital records and linked with Finnish Cancer Registry data. The follow-up started from the first TL-01 treatment and the mean follow-up time was 8.4 years. Standardized incidence ratios were calculated for basal cell carcinoma, cutaneous melanoma, and squamous cell carcinoma. The standardized incidence ratio for basal cell carcinoma was 2.5 (95% confidence interval 1.8-3.5), for cutaneous melanoma 4.0 (95% confidence interval 2.1-6.8) and for squamous cell carcinoma 3.7 (95% confidence interval 1.7-7.0). For basal cell carcinoma and squamous cell carcinoma, the standardized incidence ratios remained similar during the whole follow-up time while the standardized incidence ratio for cutaneous melanoma was markedly higher during the first 5 years of follow-up. In conclusion, an increased incidence of skin cancers was observed among TL-01 treated patients. It should be confirmed in the future whether the skin cancer risk of TL-01 phototherapy will remain high in a longer follow-up.

Have the recent advancements in cancer therapy and survival benefitted patients of all age groups across the Nordic countries? NORDCAN survival analyses 2002-2021.

BACKGROUND: Since the early 2000s, overall and site-specific cancer survival have improved substantially in the Nordic countries. We evaluated whether the improvements have been similar across countries, major cancer types, and age groups. MATERIAL AND METHODS: Using population-based data from the five Nordic cancer registries recorded in the NORDCAN database, we included a cohort of 1,525,854 men and 1,378,470 women diagnosed with cancer (except non-melanoma skin cancer) during 2002-2021, and followed for death until 2021. We estimated 5-year relative survival (RS) in 5-year calendar periods, and percentage points (pp) differences in 5-year RS from 2002-2006 until 2017-2021. Separate analyses were performed for eight cancer sites (i.e. colorectum, pancreas, lung, breast, cervix uteri, kidney, prostate, and melanoma of skin). RESULTS: Five-year RS improved across nearly all cancer sites in all countries (except Iceland), with absolute differences across age groups ranging from 1 to 21 pp (all cancer sites), 2 to 20 pp (colorectum), -1 to 36 pp (pancreas), 2 to 28 pp (lung), 0 to 9 pp (breast), -11 to 26 pp (cervix uteri), 2 to 44 pp (kidney), -2 to 23 pp (prostate) and -3 to 30 pp (skin melanoma). The oldest patients (80-89 years) exhibited lower survival across all countries and sites, although with varying improvements over time. INTERPRETATION: Nordic cancer patients have generally experienced substantial improvements in cancer survival during the last two decades, including major cancer sites and age groups. Although survival has improved over time, older patients remain at a lower cancer survival compared to younger patients.

Melanoma epidemiology in Europe: what is new?

Every year in Europe over 150,000 new cases of melanoma are reported and over 25,000 lives are lost to this tumor. Incidence has been rising rapidly, faster than for any other cancer, and it is expected to continue to do so in most regions. Mortality also crept up, decades-long, with only few very recent exceptions. Thus, melanoma remains a public health problem that will not go away soon, nor easy. Some notable progress has been made in the last decade in the fight against this tumor. Registration and reporting for skin cancers improved across Europe. Incidence trends have begun to plateau or even to descend in younger age groups, in some countries, and there are encouraging signs that mortality might do the same, after the recent therapeutic breakthroughs. Survival rates are on average above 80% at 5 years for European patients, while diagnosis trends toward ever thinner tumors. Yet this progress is far from uniform across the continent, with many Southern-and Eastern European countries still struggling with sub-optimal cancer reporting, delayed access to innovative treatments, late detection and insufficient healthcare funding, that push survival rates down to harrowing 50%. This article aims to give an updated overview of the epidemiological situation of melanoma in Europe, highlighting the progress but also the persisting disparities in tumor burden, prognosis and access to quality cancer care and surveillance between European countries, as a reminder that relentless efforts must continue in order to tackle this aggressive tumor in an effective and equitable manner.

A Survey of Demographics and Treatments in Melanoma Case Reports: Retrospective Bibliometric Analysis.

Melanoma case reports show variations in treatment by age and sex.

Immunohistochemistry for Diagnosing Melanoma in Older Adults.

Importance: Pathologic assessment to diagnose skin biopsies, especially for cutaneous melanoma, can be challenging, and immunohistochemistry (IHC) staining has the potential to aid decision-making. Currently, the temporal trends regarding the use of IHC for the examination of skin biopsies on a national level have not been described. Objective: To illustrate trends in the use of IHC for the examination of skin biopsies in melanoma diagnoses. Design, Setting, and Participants: A retrospective cross-sectional study was conducted to examine incident cases of melanoma diagnosed between January 2000 and December 2017. The analysis used the SEER-Medicare linked database, incorporating data from 17 population-based registries. The study focused on incident cases of in situ or malignant melanoma of the skin diagnosed in patients 65 years or older. Data were analyzed between August 2022 and November 2023. Main Outcomes and Measures: The main outcomes encompassed the identification of claims for IHC within the month of melanoma diagnoses and extending up to 14 days into the month following diagnosis. The SEER data on patients with melanoma comprised demographic, tumor, and area-level characteristics. Results: The final sample comprised 132 547 melanoma tumors in 116 117 distinct patients. Of the 132 547 melanoma diagnoses meeting inclusion criteria from 2000 to 2017, 43 396 cases had accompanying IHC claims (33%). Among these cases, 28 298 (65%) were diagnosed in male patients, 19 019 (44%) were diagnosed in patients aged 65 years to 74 years, 16 444 (38%) in patients aged 75 years to 84 years, and 7933 (18%) in patients aged 85 years and older. In 2000, 11% of melanoma cases had claims for IHC at or near the time of diagnosis. This proportion increased yearly, with 51% of melanoma cases having associated IHC claims in 2017. Increasing IHC use is observed for all stages of melanoma, including in situ melanoma. Claims for IHC in melanomas increased in all 17 SEER registries but at different rates. In 2017, the use of IHC for melanoma diagnosis ranged from 39% to 68% across registries. Conclusions and Relevance: Considering the dramatically rising and variable use of IHC in diagnosing melanoma by pathologists demonstrated in this retrospective cross-sectional study, further investigation is warranted to understand the clinical utility and discern when IHC most improves diagnostic accuracy or helps patients.