The Clinicopathological and Survival Profiles Comparison Across Primary Sites in Acral Melanoma

Establishment and Validation of Prognostic Nomograms for Nonmetastatic Melanoma of the Limbs-A SEER-Based Study

BACKGROUND

Malignant melanoma, a highly aggressive skin cancer, has remarkable incidence and mortality nowadays. This study aims to explore prognostic factors associated with nonmetastatic cutaneous melanoma of the limbs and to develop nomograms for predicting overall survival (OS) and cancer-specific survival (CSS).

METHODS

The study cohort was derived from the Surveillance, Epidemiology, and End Results database. Univariate Cox regression, Lasso regression, and multivariate Cox regression analyses were conducted to identify prognostic factors and construct nomograms. The receiver operating characteristic (ROC) curve, time-dependent C-index, calibration curve, decision curve analysis (DCA) and Kaplan-Meier method were used to evaluate the accuracy and clinical applicability of the nomograms.

RESULTS

A total of 15,606 patients were enrolled. Multivariate analysis identified several prognostic factors for OS and CSS including age, sex, histologic type, N stage, tumor thickness, depth of invasion, mitotic rate, ulceration, surgery of primary site, systemic therapy, race, and number of lymph nodes examined. A nomogram incorporating 12 independent predictors for OS was developed, with a C-index of 0.866 (95% confidence interval [CI]: 0.858-0.874) in the training cohort and 0.853 (95% CI: 0.839-0.867) in validation. For CSS, 10 independent predictors and one related factor were included, yielding a C-index of 0.913 (95% CI: 0.903-0.923) in the training cohort and 0.922 (95% CI: 0.908-0.936) in validation. The ROC curve, time-dependent C-index, calibration curve, DCA, and K-M plot demonstrated favorable discrimination, calibration, and clinical utility.

CONCLUSION

The developed nomograms provide a precise and personalized predictive tool for risk management of patients with nonmetastatic limb melanoma.

Beyond the Scalpel: Advancing Strategic Approaches and Targeted Therapies in Nonexcisable Melanomas

Melanoma in challenging anatomical locations such as the face, acral surfaces, and mucosal areas presents unique hurdles for surgical excision. This review examines alternative nonsurgical treatment modalities in the context of these complexities, addressing the gaps in current guidelines and the varied efficacy of existing therapies. A comprehensive literature search was conducted using PubMed, Embase, and Web of Science databases. The review focuses on peer-reviewed articles discussing nonsurgical treatment options for melanoma in complex anatomical locations. Articles were screened by three independent researchers, ensuring a broad analysis of topical agents, immunotherapies, radiotherapies, and targeted therapies. The review highlights significant advancements in localized treatments such as imiquimod and intralesional therapy with talimogene laherparepvec (T-VEC), which show promise in managing nonexcisable melanomas. BRAF and MEK inhibitors, as well as checkpoint inhibitors targeting CTLA-4 and PD-1/PD-L1 pathways, demonstrate improved survival rates but pose challenges with resistance and systemic side effects. Radiotherapy serves as an adjunctive strategy due to melanoma's inherent radioresistant properties. Despite advancements, there is a notable absence of comprehensive, evidence-based protocols to guide the treatment of melanoma in these critical areas. This paper underscores the need for standardized treatment guidelines that account for the efficacy, side effects, and psychosocial impacts of therapies. Future research should focus on refining existing treatments and exploring innovative modalities to enhance patient outcomes in the management of nonexcisable melanomas. Comprehensive guidelines and long-term efficacy studies are essential to optimize care and improve the quality of life for patients afflicted with melanoma in challenging anatomical locations.

Depth of invasion analysis to predict acral melanoma outcomes

BACKGROUND

Acral melanoma is a subtype with worse outcomes. The Breslow micrometric measurement is the most critical parameter in planning treatment and predicting outcomes. However, for acral lentiginous melanoma, the value of the Breslow thickness is a matter of debate. Depth of Invasion (DOI) is a well-established measure for staging oral squamous cell carcinoma.

OBJECTIVE

This study compared DOI and Breslow thickness for predicting acral melanoma outcomes.

METHODS

We performed a retrospective cross-sectional study of 71 acral melanoma lesions subjected to sentinel lymph node biopsy at one Brazilian referral center.

RESULTS

Cox model univariate analysis showed that both DOI and Breslow thickness predicted melanoma specific survival (HR 1.12; p = 0.0255 and HR 1.144; p = 0.0006, respectively), although Kaplan Meier curve was only significant for Breslow (χ2 = 5.792; p = 0.0161) and not for DOI (χ2 = 0.2556; p = 0.6132). Sentinel lymph node status and presence or absence of ulceration also predicted specific survival in patients with acral melanoma (χ2 = 6.3514; p = 0.0117 and χ2 = 4.2793; p = 0.0386, respectively). Multivariate analysis, however, demonstrated that Breslow depth was the only independent parameter for predicting acral melanoma specific survival (HR 1.144; p = 0.0006).

CONCLUSION

Even though Breslow thickness remains the main predictor for survival in acral melanoma, it is not a perfect parameter. The introduction of DOI in this context opens new perspectives for predicting acral melanoma outcomes.

Prognostic and Predictive Significance of Ki67 in Primary Non-metastatic or Recurrent Acral Melanoma: Evidence from a Multicenter Retrospective Study

BACKGROUND

The purpose of this work was to investigate the prognostic significance of Ki67 in acral melanoma (AM).

PATIENTS AND METHODS

Ki67 values in primary lesions (pKi67) of 481 patients with primary non-metastatic AM (primary cohort) from three tertiary hospitals and in recurrent lesions (rKi67) of 97 patients (recurrent cohort) were recorded. The associations of p/rKi67 with clinicopathological features and prognosis were analyzed.

RESULTS

In the primary cohort, high pKi67 group tended to have more ulceration, pT4, lymph node metastasis (LNM), nodal macrometastases, and recurrence (all P < 0.05). Logistic regression analysis revealed that pKi67 was significantly associated with pT4 and LNM (P = 0.004 and 0.027, respectively). Furthermore, both 5-year overall survival (OS) and recurrence-free survival (RFS) rates in high pKi67 group were significantly worse than those in moderate and low pKi67 groups (OS 47.8% versus 55.7 versus 76.8%, P = 0.002; RFS: 27.1 versus 42.8 versus 61.8%, P < 0.001). Similarly, in the recurrent cohort, the 5-year survival after recurrence (SAR) rates in high rKi67 group was significantly worse than those in moderate and low rKi67 groups (31.7 versus 47.4 versus 75%; P = 0.026). Stratified analysis also indicated a significant survival difference among pKi67 groups within various subgroups. Most importantly, multivariate Cox analysis demonstrated that pKi67 could be independently associated with OS and RFS, as well as rKi67 for SAR (all P < 0.05).

CONCLUSIONS

A high Ki67 value was significantly associated with adverse pathological and prognostic features in both primary and recurrent AM cohorts. Ki67 should be routinely evaluated to guide risk stratification and prognostic prediction.

Clinical characteristics, survival analysis and influencing factors of distant metastasis in patients with acromelanomas: A retrospective study

The prognosis of acromelanomas (AM) is worse. The objective of this study was to investigate the clinical features of distant metastasis of AM and the factors affecting the survival and prognosis of patients. In this study, a retrospective study was conducted to select 154 AM patients admitted to Nanjing Pukou People's Hospital from January 2018 to April 2021 for clinical research. The clinical characteristics of distant metastasis were statistically analyzed, and the survival curve was drawn with 5-year follow-up outcomes. The median survival time of the patients was calculated, and the clinicopathological features and peripheral blood laboratory indexes of the surviving and dead patients were analyzed. Logistic regression model was used to analyze the risk factors affecting the prognosis of AM patients. In this study, 154 patients with AM were treated, including 88 males and 76 females, aged from 27 to 79 years old, with an average age of (59.3 ± 11.7) years old. Among them, 90 cases had distant metastasis. The main metastatic sites were lung (47.78%) and lymph nodes (42.22%). Among them, single site metastasis accounted for 41.11% and multiple site metastasis 58.89%. 89 cases survived and 65 cases died. The survival time was 22 months to 60 months, and the median survival time was 48.0 months. The Breslow thickness, stage at diagnosis, distant metastasis, site of metastasis and ulceration were compared between the survival group and the death group (P < .05). serum lactate dehydrogenase (LDH), neutrophil-to-lymphocyte ratio (NLR) and lymphocyte monocyte ratio (LMR) were compared between the survival group and the death group (P < .05). The results of Logistic regression model showed that LDH ≥ 281 U/L, NLR ≥ 2.96, LMR ≤ 3.57, newly diagnosed stage > stage II, distant metastasis, multiple site metastasis and tumor ulcer were independent risk factors for poor prognosis of AM patients (P < .05). Patients with AM had a higher proportion of distant metastasis, mainly lung and lymph node metastasis. Increased LDH, increased NLR, decreased LMR, higher initial stage, distant metastasis, multiple site metastasis, and combined tumor ulcer were closely related to the poor prognosis of patients after surgery.

Rosacea is strongly associated with melanoma in Caucasians

Rosacea is often considered a cosmetic problem but is known to be associated with a variety of comorbidities. To identify such risks, we generated two age- and sex-matched real-world cohorts of 122,444 patients each with and without rosacea. In contrast to earlier studies, we found significant associations with malignant melanoma (OR 6.02, 95% CI 5.76-6.32). This association does not exist for an Asian sub-cohort, which could explain previous inconclusive or conflicting reports. Several strongly associated comorbidities like visual disturbances (ICD-10: H53-H54; OR 4.80, 4.68-4.92), metabolic disorders (E73-E79; OR 3.17, 3.11-3.22), joint problems (M25; OR 4.16, 4.08-4.25) and type 2 diabetes (E11; OR 1.62, 1.58-1.65) should be watched as a risk for rosacea patients. Rosacea is associated with some comorbidities and ethnicity may be a risk factor in melanoma development. The retrospective nature of this study and the sole use of ICD-10 code based filtering calls for future validation of our findings. Additionally, confounding factors such as skin type and previous UV exposure should be included in future studies.

Research hotspots and frontiers in acral melanoma: A bibliometric analysis from 1999 to 2023

Background

Acral melanoma (AM), an aggressive subtype of melanoma with poor prognosis, has been increasingly studied. The present study aims to discuss the current status, hotspots and future directions of AM studies through visualized analysis with bibliometrics and knowledge graph.

Method

Publications related to acral melanoma from January 1999 to May 2023 were searched and retrieved from the Web of Science. Data extraction and visualization of the top 10 publications by year of publication, journal, country and core author were performed using R Studio (Version 4.3.0) and Scimago Graphica (Version 1.0.34). Co-reference graphs regarding country/region, organization, author, and keywords, as well as reference collaborative network, co-occurrence network, and references were plotted using VOSviewer (Version 1.6.19) and CiteSpace (Version 6.2.R3).

Results

A total of 1387 articles related to AM published in English from 1999 to 2023 were included in the present study. A total of 7499 authors were from 2092 organizations in 50 countries. The articles were published in 356 journals, involving 4131 keywords and 28,200 references. The 1387 articles related to AM had been cited a total of 10,014 times by the time of this study. The result showed that Journal of the American Academy of Dermatology had the largest number of citations and citation rate, with a total of 60 publications having been cited 2191 times. Having the top three productivity institutions in the world, the US is the most productive country in this field, with a total of 361 publications. The authors with the highest number of publications were Guo Jun (n = 43) and Si Lu (n = 38) from Peking University. The keyword burstiness test found that "ipilimumab", "open label", "efficacy" and "nivolumab" appeared most frequently in recent years. The co-cited reference timeline graph showed that the clustering of "advanced melanoma" and "melanocytic lesion" has been a hotspot since 2016.

Conclusions

The number of AM-related studies has been increasing. The clinical characteristics and immunotherapy of AM are still key research directions, with the US playing a leading role in this field. This bibliometric analysis found up to 1387 publications, which not only comprehensively and quantitatively reflected the research trends and hotspots, but also provided a theoretical basis for future studies of AM. Researchers can benefit from choosing the right journals and finding potential collaborators or partner institutions.

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.

Treatment of acral and mucosal melanoma: Current and emerging targeted therapies

Targeted therapies revolutionized the management of patients with advanced and metastatic cutaneous melanoma. However, despite recent advances in the understanding of the molecular drivers of melanoma and its treatment with targeted therapies, patients with rare and aggressive melanoma subtypes, including acral melanoma (AM) and mucosal melanomas (MM), show limited long-term clinical benefit from current targeted therapies. While patients with AM or MM and BRAF or KIT mutations may benefit from targeted therapies, the frequency of these mutations is relatively low, and there are no genotype-specific treatments for most patients with AM or MM who lack common driver mutations. The poor prognosis of AM and MM can also be attributed to the lack of understanding of their unique molecular landscapes and clinical characteristics, due to being under-represented in preclinical and clinical studies. We review current knowledge of the molecular landscapes of AM and MM, focusing on actionable therapeutic targets and pathways for molecular targeted therapies, to guide the development of more effective targeted therapies for these cancers. Current and emerging strategies for the treatment of these melanoma subtypes using targeted therapies are also summarized.

A nomogram incorporating Ki67 to predict survival of acral melanoma

BACKGROUND

The proliferation marker Ki67 is associated with the progression and prognosis of melanoma. However, its prognostic impact on acral melanoma (AM) remains unclear.

METHODS

A total of 314 AM patients were enrolled from a cohort of 5758 patients with melanoma at Peking University Cancer Hospital between 2006 and 2018. The patients were divided into Ki67 high- and low-expressing groups using a cut-off value of 30%. The associations between Ki67 and clinicopathologic characteristics as well as survival were analyzed. Cox proportional regression analysis was used to establish a nomogram to predict the survival probabilities of AM.

RESULTS

Among 314 patients, the Ki67-high group (Ki67 ≥ 30%) included 49.4% of patients at diagnosis. Patients in the Ki67-high group had lower median melanoma-specific survival (MSS) than those in the Ki67-low group (60.7 months vs. not reached, p < 0.001). In multivariate analyses, Ki67, lymph node metastasis and primary site were independent prognostic factors for MSS. The nomogram showed that Ki67 had the fourth greatest impact on survival, following Breslow thickness, lymph node metastasis and primary site. The C-index of the nomogram was 0.765 and 0.758 in the training and validation cohort, respectively. Area under the curve values were both near 0.8 in the training and validation cohorts. Net reclassification improvement and integrated discrimination improvement demonstrated that the predictive nomogram performed better than the traditional AJCC staging system.

CONCLUSION

Ki67 expression is an independent prognostic factor for MSS in AM. A predictive model incorporating Ki67 and clinical factors was constructed to predict the prognosis of AM.

Survival impact of immediate complete lymph node dissection for Chinese acral and cutaneous melanoma with micrometastasis in sentinel nodes: a retrospective study

Sentinel node biopsy (SNB) has become a critical part of standard surgical treatment for melanoma with no clinical metastatic evidence. However, for patients with a positive sentinel node, the MSLT-II and DeCOG-SLT trials have shown that immediate complete lymph node dissection (CLND) does not bring further survival benefits. There is still an argument among the Chinese population dominated by acral subtypes on whether CLND can be omitted. Thus, this study aims to investigate the impact of immediate CLND on relapse-free survival (RFS) in Chinese melanoma patients with a positive sentinel node. Patients with acral or cutaneous melanoma of clinical Stages I-II who received SNB procedure and were detected with nodal micrometastasis were retrospectively collected at Fudan University Cancer Center (FUSCC) from January 2017 to December 2021. The clinicopathologic features and prognostic factors for RFS were analyzed. Out of 381 patients who received SNB in the past 5 years, 130 (34%) cases with SN micrometastasis detected were included in this study. Ninety-nine patients underwent immediate CLND while the other 31 patients received observation alone. Among patients who received CLND, the non-SN(NSN)-positive rate was 22.2%. Most of the clinicopathologic factors were balanced well between the CLND and non-CLND groups. However, more patients in the CLND group were detected with BRAF and NRAS mutation (P = 0.006) and received adjuvant PD-1 monotherapy (P = 0.042) as well. There were slightly fewer N1 patients in the CLND group, although the difference did not reach statistical significance (P = 0.075). The study found no significant difference in RFS between the two groups (P = 0.184). Even for patients with the acral subtype (P = 0.925), primary T4 lesion (P = 0.769), or presence of ulceration (P = 0.249), immediate CLND did not bring more survival benefits. Immediate CLND did not bring further RFS benefit for Chinese melanoma patients with SN micrometastasis in real-world clinical practice, even for patients with acral subtype or more tumor burden such as thick Breslow invasion and ulceration.

Update on nail unit histopathology

Histopathologic evaluation of the nail unit is an essential component in the diagnosis of nail unit disorders. This review highlights recent updates in nail unit histopathology and discusses literature covering a wide range of nail disorders including melanoma/melanocytic lesions, squamous cell carcinoma, onychomatricoma, onychopapilloma, onychomycosis, lichen planus, and other inflammatory conditions. Herein we also discuss recent literature on nail clipping histopathology, a useful and noninvasive diagnostic tool that continues to grow in popularity and importance to both dermatologists and dermatopathologists.

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.

Acral Melanoma Is Infiltrated with cDC1s and Functional Exhausted CD8 T Cells Similar to the Cutaneous Melanoma of Sun-Exposed Skin

Acral melanoma (AM) is the most common melanoma in non-Caucasian populations, yet it remains largely understudied. As AM lacks the UV-radiation mutational signatures that characterize other cutaneous melanomas, it is considered devoid of immunogenicity and is rarely included in clinical trials assessing novel immunotherapeutic regimes aiming to recover the antitumor function of immune cells. We studied a Mexican cohort of melanoma patients from the Mexican Institute of Social Security (IMSS) (n = 38) and found an overrepresentation of AM (73.9%). We developed a multiparametric immunofluorescence technique coupled with a machine learning image analysis to evaluate the presence of conventional type 1 dendritic cells (cDC1) and CD8 T cells in the stroma of melanoma, two of the most relevant immune cell types for antitumor responses. We observed that both cell types infiltrate AM at similar and even higher levels than other cutaneous melanomas. Both melanoma types harbored programmed cell death protein 1 (PD-1+) CD8 T cells and PD-1 ligand (PD-L1+) cDC1s. Despite this, CD8 T cells appeared to preserve their effector function and expanding capacity as they expressed interferon-γ (IFN-γ) and KI-67. The density of cDC1s and CD8 T cells significantly decreased in advanced stage III and IV melanomas, supporting these cells' capacity to control tumor progression. These data also argue that AM could respond to anti-PD-1-PD-L1 immunotherapy.

Application of fluorescence in situ hybridization in distinguishing acral melanoma in situ from acral junctional melanocytic nevus on the volar skin in Japanese patients

Four-colored fluorescence in situ hybridization (FISH) is an ancillary diagnostic tool for melanoma. However, most studies that have investigated the usefulness of FISH primarily focused on advanced melanomas. The aim of the current study was to evaluate the effectiveness of FISH in distinguishing acral melanoma (AM) in situ from benign acral junctional nevus (AJN), two types of lesions that are difficult to differentiate via traditional clinical means. The authors investigated the usefulness of FISH in 91 acral melanocytic lesions, including 50 lesions with diagnostic discrepancies between dermoscopic and pathologic approaches or difficulty diagnosing between AM in situ and AJN, on the volar skin of Japanese patients. The authors classified the lesions based on the diagnosis of dermatologists and pathologists into four groups: (I) lesions with a unanimous diagnosis by dermatologists and pathologists as AM in situ or AJN (n = 41); (II) lesions with a unanimous diagnosis by dermatologists only as AM in situ or AJN (n = 21); (III) lesions with a unanimous diagnosis by pathologists only as AM in situ or AJN (n = 15); and (IV) all other lesions (n = 14). The dermatologists diagnosed the lesions by clinical and dermoscopic photographs alone, while the pathologists diagnosed the lesions by microscopy of hematoxylin and eosin-stained slides alone. In group I (AM in situ [n = 20] and AJN [n = 21]), four-colored FISH demonstrated 90% sensitivity and 81% specificity in distinguishing AM in situ from AJN. There was a significant correlation between the FISH results and the unanimous diagnoses by pathologists alone (p = 0.03) in group III. However, FISH results were not significantly correlated with the unanimous diagnoses by dermatologists alone (p = 0.33) in group II. In conclusion, the four-colored FISH probe kit was useful in distinguishing between AM in situ and AJN and may be an ancillary method when pathologists who are not experts of dermatopathology diagnose melanocytic lesions.

Prognostic impact of Breslow thickness in acral melanoma: A retrospective analysis

BACKGROUND

Evidence for the prognostic importance of tumor thickness in acral melanoma (AM) patients is limited.

OBJECTIVE

The objective of the study was to determine the prognostic impact of Breslow thickness in AM.

METHODS

This multicenter study enrolled patients diagnosed with localized AM between January 1, 2000 and December 31, 2017. Melanoma-specific survival (MSS) in different tumor thickness strata (T1-T4: ≤1, >1-2, >2-4, >4 mm, respectively) was estimated by the Kaplan-Meier method. Comparisons were performed by the log-rank test and multivariable Cox regression.

RESULTS

A total of 853 patients with clinical N0 (cN0) AM were included in the analysis. The median follow-up time was 60.1 months. The median MSS in patients with T1-T4 disease was not reached, 111.0, 92.8, and 67.1 months, respectively. MSS differed significantly among cN0 patients with T1-T3 AM (log-rank P = .004, .012, <0.001 for T1 vs T2, T2 vs T3, and T1 vs T3, respectively); however, there was no significant difference between T3 and T4 AM (hazard ratio = 0.82, 95% CI, 0.62-1.09). Six-subgroup analyses confirmed that survival outcomes were similar between different subgroups with tumor thickness >2 mm.

LIMITATIONS

The limitations were retrospective design and some missing variables.

CONCLUSIONS

There was no association between tumor thickness and survival in AM patients with a Breslow thickness >2 mm.

Immunotherapy Options for Acral Melanoma, A fast-growing but Neglected Malignancy

Melanoma is the deadliest form of skin cancer. It is classified as cutaneous and non-cutaneous, with the former characterized by developing in sun-exposed areas of the skin, UV-light radiation being its most important risk factor and ordinarily affecting fair skin populations. In recent years, the incidence of melanoma has been increasing in populations with darker complexion, for example, Hispanics, in which acral melanoma is highly prevalent. The WHO estimates that the incidence and mortality of melanoma will increase by more than 60% by 2040, particularly in low/medium income countries. Acral melanoma appears in the palms, soles and nails, and because of these occult locations, it is often considered different from other cutaneous melanomas even though it also originates in the skin. Acral melanoma is very rare in Caucasian populations and is often not included from genetic analysis and clinical trials. In this review, we present the worldwide epidemiology of acral melanoma; we summarize its genetic characterization and point out important signaling pathways for targeted therapy. We also discuss how genetic analyses have shown that acral melanoma carries a sufficient mutational load and neoantigen formation to be targeted by the immune system, arguing for a potential benefit with novel immunotherapeutic strategies, alone or combined with targeted therapy. This is important because chemotherapy remains the first-line treatment in non-developed nations despite a disheartening response. In summary, the increased incidence and mortality of acral melanoma in low/medium income countries calls for increasing our knowledge about its nature and therapeutic options and leveling off the asymmetric research conducted primarily on Caucasian populations.

Clinicopathological characteristics and prognosis in significantly thick acral lentiginous melanoma in Taiwan

This retrospective cohort study enrolled 385 patients diagnosed with cutaneous melanoma from 1980 to 2021 in National Taiwan University Hospital (NTUH). The aim of this study was to investigate the relationship between thickness of primary melanoma lesions and disease outcome of melanoma patients, in particular, those diagnosed with acral lentiginous melanoma (ALM). The association between important clinicopathological characteristics other than tumor thickness and disease outcome was also analyzed. Survival analyses with the Kaplan-Meier method were utilized to investigate the prognoses of patients with different lesion thickness. The male-to-female ratio was 1.12:1. The median age at diagnosis was 63 years old (mean: 62.2 years). There were 283 cases (73.5%) of acral lentiginous melanoma (ALM) with a male-to-female ratio of 1.04:1. Between patients with primary ALM lesions 4.1 millimeters (mm) to 8.0 mm thick and those with lesions over 8.0 mm thick, significant differences in prognostic outcomes including incidence of second recurrences within 1 year (raw p = 0.003, Bonferroni corrected p = 0.009) and distant metastases within 1 year (raw p = 0.003, Bonferroni corrected p = 0.008), were observed. Significantly worse 1-year (raw p = 0.01, Bonferroni corrected p=0.03) and 2-year survival (raw p = 0.006, Bonferroni corrected p = 0.02) were found in ALM patients with lesions of over 8 mm thick than those with lesions 4.1 mm to 8.0 mm at diagnosis. Vigilant short-term follow-up is warranted in ALM patients with lesions of over 8.0 mm thick at diagnosis due to higher risks of adverse outcome.

Preoperative Ultrasound-Guided Incisional Biopsy Enhances the Pathological Accuracy of Incisional Biopsy of Cutaneous Melanoma: A Prospective Clinical Trial in Chinese Patients

OBJECTIVES

To assess the feasibility of preoperative ultrasound (US)-guided incisional biopsy through a prospective controlled clinical trial.

METHODS

This was a prospective, double-arm, single-center study of Chinese patients. Thirty patients were enrolled in the study. Fourteen patients received incisional biopsies for which the choice of biopsy area relied on a clinical evaluation, and 16 patients received incisional biopsies for which the choice of biopsy area relied on a US-guided evaluation. The following procedure was used in the US-guided incisional biopsy group: 1) clinical and dermoscopic evaluation of skin lesions; 2) US examination; 3) incisional biopsy; 4) surgical excision; and 5) histopathological examination. The same procedure was used in the non-US-guided group except without US examination.

RESULTS

In the non-US-guided group, the mean tumor thicknesses obtained from incisional biopsy and postoperative histopathological examination were 2.1 and 4.1 mm, respectively. Seven melanomas were underestimated by incisional biopsy, resulting in margins narrower than currently recommended. In the US-guided group, the mean tumor thicknesses obtained from US, incisional biopsy, and postoperative histopathological examination were 3.4, 2.9, and 2.7 mm, respectively. In only 3 melanomas was the tumor thickness of the incisional biopsy less than that of the postoperative histopathological examination, demonstrating that US-guided biopsy obtains the maximum thickness area.

CONCLUSIONS

Preoperative US-guided incisional biopsy can enhance the pathological accuracy of incisional biopsy, which may allow us to better perform surgical excision with safe peripheral surgical margins.

Clinical features, molecular pathology, and immune microenvironmental characteristics of acral melanoma

Acral melanoma (AM) has unique biology as an aggressive subtype of melanoma. It is a common subtype of melanoma in races with darker skin tones usually diagnosed at a later stage, thereby presenting a worse prognosis compared to cutaneous melanoma. The pathogenesis of acral melanoma differs from cutaneous melanoma, and trauma promotes its development. Compared to cutaneous melanomas, acral melanomas have a significantly lighter mutational burden with more copy number variants. Most acral melanomas are classified as triple wild-type. In contrast to cutaneous melanomas, acral melanomas have a suppressive immune microenvironment. Herein, we reviewed the clinical features, genetic variants, and immune microenvironmental characteristics of limbic melanomas to summarise their unique features.

Efficacy of anti-PD-1 and ipilimumab alone or in combination in acral melanoma

BACKGROUND

Acral melanoma is a rare melanoma subtype with poor prognosis. Importantly, these patients were not identified as a specific subgroup in the landmark melanoma trials involving ipilimumab and the anti-programmed cell death protein-1 (PD-1) agents nivolumab and pembrolizumab. There is therefore an absence of prospective clinical trial evidence regarding the efficacy of checkpoint inhibitors (CPIs) in this population. Acral melanoma has lower tumor mutation burden (TMB) than other cutaneous sites, and primary site is associated with differences in TMB. However the impact of this on the effectiveness of immune CPIs is unknown. We examined the efficacy of CPIs in acral melanoma, including by primary site.

METHODS

Patients with unresectable stage III/IV acral melanoma treated with CPI (anti-PD-1 and/or ipilimumab) were studied. Multivariable logistic and Cox regression analyses were conducted. Primary outcome was objective response rate (ORR); secondary outcomes were progression-free survival (PFS) and overall survival (OS).

RESULTS

In total, 325 patients were included: 234 (72%) plantar, 69 (21%) subungual and 22 (7%) palmar primary sites. First CPI included: 184 (57%) anti-PD-1, 59 (18%) anti-PD-1/ipilimumab combination and 82 (25%) ipilimumab. ORR was significantly higher with initial anti-PD-1/ipilimumab compared with anti-PD-1 (43% vs 26%, HR 2.14, p=0.0004) and significantly lower with ipilimumab (15% vs 26%, HR 0.49, p=0.0016). Landmark PFS at 1 year was highest for anti-PD-1/ipilimumab at 34% (95% CI 24% to 49%), compared with 26% (95% CI 20% to 33%) with anti-PD-1 and 10% (95% CI 5% to 19%) with ipilimumab. Despite a trend for increased PFS, anti-PD-1/ipilimumab combination did not significantly improve PFS (HR 0.85, p=0.35) or OS over anti-PD-1 (HR 1.30, p=0.16), potentially due to subsequent therapies and high rates of acquired resistance. No outcome differences were found between primary sites.

CONCLUSION

While the ORR to anti-PD-1/ipilimumab was significantly higher than anti-PD-1 and PFS numerically higher, in this retrospective cohort this benefit did not translate to improved OS. Future trials should specifically include patients with acral melanoma, to help determine the optimal management of this important melanoma subtype.

Integrative Genomic Profiling Uncovers Therapeutic Targets of Acral Melanoma in Asian Populations

PURPOSE

Acral melanoma is the major subtype of melanoma seen in Asian patients with melanoma and is featured by its insidious onset and poor prognosis. The genomic study that elucidates driving mutational events is fundamental to the development of gene-targeted therapy. However, research on genomic profiles of acral melanoma in Asian patients is still sparse.

EXPERIMENTAL DESIGN

We carried out whole-exome sequencing (WES) on 60 acral melanoma lesions (with 55 primary samples involved), targeted deep sequencing in a validation cohort of 48 cases, RNA sequencing in 37 acral melanoma samples (all from the 60 undergoing WES), and FISH in 233 acral melanoma specimens (54 of the 60 undergoing WES included). All the specimens were derived from Asian populations.

RESULTS

BRAF, NRAS, and KIT were discerned as significantly mutated genes (SMG) in acral melanoma. The detected COSMIC signature 3 related to DNA damage repair, along with the high genomic instability score, implied corresponding pathogenesis of acral melanoma. Moreover, the copy number gains of EP300 were associated with the response of acral melanoma to targeted therapy of A485 (a p300 inhibitor) and immune checkpoint blockade treatment. In addition, the temporal order in mutational processes of the samples was reconstructed, and copy-number alterations were identified as early mutational events.

CONCLUSIONS

Our study provided a detailed view of genomic instability, potential therapeutic targets, and intratumoral heterogeneity of acral melanoma, which might fuel the development of personalized strategies for treating acral melanoma in Asian populations.

Does acral melanoma need a distinctive prognostic staging system?

Linked Article: Wei et al. Br J Dermatol 2022; 186 :977–987 .

Actionable Mutation Profile of Sun-Protected Melanomas in South America

ABSTRACT

Melanomas that arise in sun-protected sites, including acral and oral mucosal melanomas, are likely under the control of unique, specific mechanisms that lead to mutagenesis through various pathways. In this study, we examined somatic mutations in tumors by targeted sequencing using a custom Ion Ampliseq Panel, comprising hotspots of 14 genes that are frequently mutated in solid tumors. Tumor DNA was extracted from 9 formalin fixation, paraffin-embedded sun-protected melanomas (4 primary oral mucosal melanomas and 5 acral lentiginous melanomas), and we identified mutations in the NRAS, PIK3CA, EGFR, HRAS, ERBB2, and ROS1 genes. This study reveals new actionable mutations that are potential targets in the treatment of photo-protected melanomas. Additional studies on more of these melanoma subtypes could confirm our findings and identify new mutations.

More than just acral melanoma: the controversies of defining the disease

Acral melanoma (AM) is a malignant cutaneous melanocytic tumour specifically located on the palms, soles, and nail apparatus, which are areas of glabrous (hairless) skin. Acral lentiginous melanoma, a subtype of AM, represents a histopathological subtype diagnosis of cutaneous melanoma with unique morphological and structural features. Despite clear definitions, the misuse of these terms and the inconsistency in reporting the histopathological features of AM cases have become a major obstacle to the study of the disease. In this review, we discuss the epidemiology, histopathological features, prognosis, and genetic profile of AM, highlighting the differences observed when histopathological subtypes are considered. The increasing global effort to characterise AM cases from ethnically diverse populations would benefit greatly from a more consistent classification of the disease.

Immunotherapy in Acral and Mucosal Melanoma: Current Status and Future Directions

Acral and mucosal melanomas are extremely rare in Caucasians; however, they are the predominant melanoma subtypes in Asians and other non-Caucasian populations. Acral and mucosal melanomas share many clinicopathological features, including aggressive phenotypes, similar genetic landscapes, and grim prognoses. In spite of advances in melanoma management, patients with acral and mucosal melanomas show limited benefit from current therapies. The rarity of these subtypes of melanoma is a significant factor contributing to the poor understanding of these pathological subtypes and the lack of effective interventions. Furthermore, the mechanisms contributing to disparities between different types of melanoma remain largely unclear. Herein, we comprehensively review current knowledge on the clinicopathological characteristics and mutational landscapes of acral and mucosal melanomas, as well as providing an overview of current therapies for patients with these aggressive melanoma subtypes, focusing on available immunotherapeutic interventions. We also discuss pathological differences between different melanoma subtypes and summarize current knowledge on melanoma disparities between Asians and Caucasians. Finally, we discuss emerging immunotherapeutic strategies for the treatment of acral and mucosal melanomas, focusing on combination therapies with immune checkpoint inhibitors. Unraveling the unique features of acral and mucosal melanomas is key for their early diagnosis and for the development of effective therapies.

Caucasians with acral lentiginous melanoma have the same outcome as patients with stage- and limb-matched superficial spreading melanoma

PURPOSE

Acral lentiginous melanoma (ALM), a relatively rare subtype of cutaneous melanoma, has been reported to have a worse prognosis than other melanomas. We aimed to assess clinical findings in Caucasian ALM patients and compare the data with a matched cohort of superficial spreading melanoma (SSM) patients.

METHODS

We studied 63 patients with ALM and 63 randomly stage- and limb-matched patients with SSM (non-ALM). In both cohorts, guideline-adjusted diagnosis, treatment and follow-up were performed.

RESULTS

We did not observe differences in prognostic factors (e.g., tumor thickness, ulceration) between the two cohorts. Both in ALM and non-ALM patients positive sentinel lymph node was a significant independent predictor for disease relapse and melanoma-specific death. However, disease relapse and melanoma-specific death rates did not significantly differ between ALM and non-ALM patients. An overall 5-year melanoma-specific survival of 82.5% and 81% was observed in ALM and non-ALM patients, respectively.

CONCLUSIONS

Our data confirm that patients with ALM have no worse outcome than non-ALM patients when correcting for significant prognostic factors. Hence, the reportedly high rates of fatal ALM cases should not be ascribed to pathobiological differences between ALM and non-ALM but are most likely are a consequence of a delay in diagnosis and thus advanced stage of ALM.

Real-world analysis of clinicopathological characteristics, survival rates, and prognostic factors in patients with melanoma brain metastases in China

PURPOSE

We aimed to establish the clinicopathological characteristics and prognostic factors of patients with melanoma brain metastases (MBM) in the East Asian population.

METHODS

Overall survival (OS) and intracranial progression-free survival (PFS) were evaluated by Kaplan-Meier analysis. Cox regression analyses were used to determine prognostic factors associated with intracranial PFS and OS.

RESULTS

Between July 2007 and December 2019, 431 patients diagnosed with MBM were enrolled. Mucosal subtype (p = 0.013), LDH level (p = 0.014), the number of MBM ≥ 4 (p = 0.02), local treatment (p < 0.0001) and the use of PD-1 inhibitors (p < 0.0001) were independent prognostic factors for intracranial PFS. Mucosal subtype (p = 0.022), LDH level (p = 0.005), no extracranial metastasis (p = 0.01), concurrent liver metastasis (p = 0.004), local treatment (p = 0.001) and the use of PD-1 inhibitors (p < 0.0001) were independent prognostic factors for OS. Mucosal subtype brain metastases had a poor response to PD-1 inhibitors (p = 0.007), with a shorter intracranial PFS than other subtypes. In BRAF mutation patients with MBM, the first-line BRAF/MEK inhibitor therapy group had an advantage in OS compared to the first-line anti-PD-1 therapy group (p = 0.043).

CONCLUSION

Our findings depict clinical characteristics and prognostic factors of MBM in the East Asian population, suggesting the mucosal subtype as an adverse prognostic and predictive factor for patients with MBM. For BRAF mutation patients with MBM, first-line BRAF/MEK inhibitor therapy may bring a potential survival benefit compared to first-line anti-PD-1 therapy.

Immune Checkpoint Inhibitors in Advanced Acral Melanoma: A Systematic Review

INTRODUCTION

Acral melanoma (AM) has different biological characteristics from cutaneous melanoma. Although systemic therapeutic strategies for advanced AM resemble those for advanced cutaneous melanoma, the evidence of the clinical use of immune checkpoint inhibitors (ICIs) for AM is still inadequate. We aimed to systematically analyze the therapeutic effects and safety profile of ICI treatments in advanced AM.

METHODS

This systematic review was conducted in line with a previously registered protocol. Three electronic databases, conference abstracts, clinical trial registers, and reference lists of included articles were searched for eligible studies. The primary outcomes were therapeutic effects, and the secondary outcomes were the safety profiles.

RESULTS

This systematic review included six studies investigating anti-CTLA-4 immunotherapy, 12 studies investigating anti-PD-1 immunotherapy, one study investigating the combination therapy of anti-CTLA-4 and anti-PD-1, and one study investigating anti-PD-1 immunotherapy in combination with radiotherapy. In most studies investigating ipilimumab, the anti-CTLA-4 antibody, the objective response rate ranged from 11.4 to 25%, the median progression-free survival ranged from 2.1 to 6.7 months, and the median overall survival was more than 7.16 months. For studies discussing anti-PD-1 immunotherapy with nivolumab, pembrolizumab, or JS001, the objective response rate ranged from 14 to 42.9%, the median progression-free survival ranged from 3.2 to 9.2 months, and the median overall survival was more than 14 months. The combination therapy of anti-CTLA-4 and anti-PD-1 immunotherapy showed better efficacy with an objective response rate of 42.9% than single-agent therapy. The retrospective study investigating the combination therapy of anti-PD-1 immunotherapy and radiation showed no overall response. Few outcomes regarding safety were reported in the included studies.

CONCLUSIONS

ICIs, especially anti-CTLA-4 monoclonal antibodies combined with anti-PD-1 antibodies, are effective systematic treatments in advanced AM. However, there remains a lack of high-level evidence to verify their efficacy and safety and support their clinical application.