Amelanotic acral melanomas: Clinicopathological, BRAF mutation, and KIT aberration analyses

Comparative Whole-Genome Sequencing Analysis of In-situ and Invasive Acral Lentiginous Melanoma: Markedly Increased Copy Number Gains of GAB2, PAK1, UCP2, and CCND1 are Associated with Melanoma Invasion

Acral lentiginous melanoma (ALM) is the most common subtype of acral melanoma. Even though recent genetic studies are reported in acral melanomas, the genetic differences between in-situ and invasive ALM remain unclear. We aimed to analyze specific genetic changes in ALM and compare genetic differences between in-situ and invasive lesions to identify genetic changes associated with the pathogenesis and progression of ALM. We performed whole genome sequencing of 71 tissue samples from 29 patients with ALM. Comparative analyses were performed, pairing in-situ ALMs with normal tissues and, furthermore, invasive ALMs with normal and in-situ tissues. Among 21 patients with in-situ ALMs, 3 patients (14.3%) had SMIM14, SLC9B1, FRG1, FAM205A, ESRRA, and ESPN mutations, and copy number (CN) gains were identified in only 2 patients (9.5%). Comparing 13 invasive ALMs with in-situ tissues, CN gains were identified in GAB2 in 8 patients (61.5%), PAK1 in 6 patients (46.2%), and UCP2 and CCND1 in 5 patients (38.5%). Structural variants were frequent in in-situ and invasive ALM lesions. Both in-situ and invasive ALMs had very low frequencies of common driver mutations. Structural variants were common in both in-situ and invasive ALMs. Invasive ALMs had markedly increased CN gains, such as GAB2, PAK1, UCP2, and CCND1, compared with in-situ lesions. These results suggest that they are associated with melanoma invasion.

Risk factors for sentinel lymph node metastasis in Korean acral and non-acral melanoma patients

Breslow thickness, ulceration, and mitotic rate are well-known prognostic factors for sentinel lymph node (SLN) metastasis in cutaneous melanoma. We investigated risk factors, including especially the degree of pigmentation, for SLN metastasis in Korean melanoma patients. We enrolled 158, composed of Korean 107 acral and 51 non-acral melanoma patients who underwent SLN biopsy. Clinicopathologic features such as Breslow thickness, ulceration, mitotic rate, and the degree of pigmentation were evaluated. The recurrence-free survival (RFS) rate and date of recurrence were determined. Fifty-four patients (34.2%) had a positive SLN biopsy result. In a multivariate analysis, Breslow thickness (odds ratio [OR] 1.93; 95% confidence interval [CI], 1.12-3.47; p = .022) and heavy pigmentation (OR 13.14; 95% CI, 2.96-95.20, p = .002) were associated with SLN metastasis. Positive SLN patients had a higher rate of loco-regional and/or distant recurrence (hazard ratio 6.32; 95% CI, 3.39-11.79; p < .001). Heavy pigmentation was associated with poor RFS. Heavy pigmentation is an independent predictor of SLN metastasis in both acral and non-acral melanoma. Our results suggest the need for in-depth SLN evaluation of cutaneous melanoma patients with heavy pigmentation and provide clinicians with important information for determining patient prognosis.

Acral Melanocytic Neoplasms: A Comprehensive Review of Acral Nevus and Acral Melanoma in Asian Perspective

Acral melanocytic neoplasms, including acral melanocytic nevus and acral melanoma, are common melanocytic lesions in Asian populations. Both lesions occur on the volar surface of the hands and feet, and on nail units. Acral melanocytic nevi occur on the arch area of the sole, whereas acral melanomas frequently occur on weight-bearing areas of the sole, and on the fingernails. Therefore, the development of acral melanoma may be associated with chronic pressure, physical stress, or trauma. Dermoscopy is a useful adjunctive diagnostic tool for differential diagnosis. Acral melanocytic nevus is characterized by a parallel furrow pattern, whereas acral melanoma has a parallel ridge pattern. Genetic alterations are also different between the two types of lesion. BRAF and NRAS mutations are common in acral melanocytic nevus, whereas acral melanoma shows lower rates of KIT, NF1, BRAF, and NRAS mutations and remarkable copy number variations in genes such as CCND1, CDK4, hTERT, PAK1, and GAB2. Sentinel lymph node biopsy is important for staging and prognosis. Contemporary treatments for melanoma include targeted therapy for mutations and immunotherapy, such as anti-PD1 inhibitors.

Acral Amelanotic Melanoma Mimicking a Foot Ulcer

Acral amelanotic melanoma can be difficult to diagnose and is often clinically aggressive. The present report describes a case of an acral amelanotic melanoma presenting as a non-healing wound after mimicking a plantar wart for two years. The decision to biopsy a borderline-suspicious lesion on the lower extremity in an elderly individual must be weighed carefully, as lower extremity biopsy carries a risk of poor wound healing and other complications. We discuss clinical and epidemiologic features that can assist in deciding when to perform a biopsy in this setting and can improve the early detection of acral amelanotic melanoma.

Systematic review and meta-analysis of genomic alterations in acral melanoma

Acral melanoma (AM) tumors arise on the palms, soles, fingers, toes, and nailbeds. A comprehensive systematic meta-analysis of AM genomic aberrations has not been conducted to date. A literature review was carried out to identify studies sequencing AM. Whole-genome/exome data from 181 samples were identified. Targeted panel sequencing data from MSK-IMPACT were included as a validation cohort (n = 92), and studies using targeted hot spot sequencing were also collated for BRAF (n = 26 studies), NRAS (n = 21), and KIT (n = 32). Statistical analysis indicated BRAF, NRAS, PTEN, TYRP1, and KIT as significantly mutated genes. Frequent copy-number aberrations were also found for important cancer genes, such as CDKN2A, KIT, MDM2, CCND1, CDK4, and PAK1, among others. Mapping genomic alterations within the context of the hallmarks of cancer identified four components frequently altered, including (i) sustained proliferative signaling and (ii) evading growth suppression, (iii) genome instability and mutation, and (iv) enabling replicative immortality. This analysis provides the largest analysis of genomic aberrations in AM in the literature to date and highlights pathways that may be therapeutically targetable.

Volar location and degree of pigmentation are associated with poor survival and first metastasis pattern in acral melanoma

The risk factors affecting acral melanoma metastasis and prognosis remain unclear. The study included 168 patients with invasive acral melanoma who were followed for ≥3 years. We evaluated patient demographics, stages, clinicopathological features, anatomic site of melanoma including nail versus volar surface, and degree of melanoma pigmentations, sentinel lymph node biopsy results, and the first metastasis sites. Of the 168 patients (mean age 64.5 years; 52.4% male), 43 (25.6%) had invasive melanoma without metastasis, 113 (67.3%) had invasive melanoma with a first lymph node metastasis, and 12 (7.1%) had invasive melanoma with invasive melanoma with a first distant metastasis. Advanced T stage, high mitotic rate, ulceration, and the degree of pigmentation were significant risk factors for metastasis. Amelanotic and mild pigmentation of acral melanoma was associated with first distant metastasis, whereas heavy pigmentation was associated with first lymph node metastasis. Advanced TNM stages, high mitotic rate, volar location (hazard ratio = 2.24, 95% confidence interval 1.18-4.26), and low-pigmentation (hazard ratio = 2.02, 95% confidence interval 1.17-3.49) were associated with melanoma-specific mortality.

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.

The role of UVA radiation in ketoprofen-mediated BRAF-mutant amelanotic melanoma cells death - A study at the cellular and molecular level

Malignant melanoma is the cause of 80% of deaths in skin cancer patients. Treatment of melanoma in the 4th stage of clinical advancement, in which inoperable metastasis occur, does not provide sufficient effects. Ketoprofen has phototoxic properties and it can be used as a new treatment option for skin cancers as a part of photochemotherapy. The present study was designed to investigate whether ketoprofen in combination with UVA induces cytotoxic, anti-proliferative and pro-apoptotic effects on melanoma cells. It was stated that co-treatment with 1.0 mM ketoprofen and UVA irradiation disturbed homeostasis of C32 melanoma cells by lowering its vitality (decrease of GSH level). Contrary to C32 cells, melanocytes showed low sensitivity to ketoprofen and UVA radiation, pointing selectivity in the mode of action towards melanoma cells. Co-treatment with ketoprofen and UVA irradiation has cytotoxic and anti-proliferative and pro-apoptotic effect on C32. The co-treatment triggered the DNA fragmentation and changed the cell cycle in C32 cells. In conclusion, it could be stated that local application of ketoprofen in combination with UVA irradiation may be used to support the treatment of melanoma and creates the possibility of reducing the risk of cancer recurrence and metastasis.

The tumor genetics of acral melanoma: What should a dermatologist know?

Dermatologists stand at the gateway of individualization of classification, treatment, and outcomes of acral melanoma patients. The acral melanoma genetic landscape differs in vital ways from that of other cutaneous melanomas. These differences have important implications in understanding pathogenesis, treatment, and prognosis. The selection of molecularly targeted therapy must be adapted for acral melanoma. It is also critical to recognize that tumor development is far more complex than an isolated event, reliably treated by a medication acting on a single target. Tumors exhibit intratumor genetic heterogeneity, metastasis may have different genetic or epigenetic features than primary tumors, and tumor resistance may develop because of the activation of alternative genetic pathways. Microenvironmental, immune, and epigenetic events contribute and sustain tumors in complex ways. Treatment strategies with multiple targets are required to effectively disrupt the tumor ecosystem. This review attempts to translate the current molecular understanding of acral melanoma into digestible concepts relevant to the practice of dermatology. The focus is tumor genetics defining potentially treatable cancer pathways, contextualized within the relevant pathologic and molecular features.

A rare case of acral amelanotic melanoma, nodular type

Amelanotic melanoma is a rare melanoma subtype, and it is even more rare when it occurs at an acral site. We here present a case of a nodular amelanotic acral melanoma (NAAM) occurring on the heel of an 83-year old female. It presented as an ulcerated pink nodular growth on the heel, which clinically mimicked other nodular non-pigmented lesions, causing a delay in diagnosis until it was biopsied. This case is a demonstration of the critical importance to include NAAM in the differential diagnosis of nodular non-pigmented skin lesions as to avoid delay in diagnosis and disease progression, in which early detection can provide the most modifiable prognostic factor.

Translational pathology, genomics and the development of systemic therapies for acral melanoma

Acral melanomas arise on the non-hair bearing skin of the palms, soles and in the nail beds. These rare tumors comprise 2-3 % of all melanomas, are not linked to UV-exposure, and represent the most frequent subtype of melanomas in patients of Asian, African and Hispanic origin. Although recent work has revealed candidate molecular events that underlie acral melanoma development, this knowledge is not yet been translated into efficacious local, regional, or systemic therapies. In the current review, we describe the clinical characteristics of acral melanoma and outline the genetic basis of acral melanoma development. Further discussion is given to the current status of systemic therapy for acral melanoma with a focus on ongoing developments in both immunotherapy and targeted therapy for the treatment of advanced disease.

Genetic Alterations in Primary Acral Melanoma and Acral Melanocytic Nevus in Korea: Common Mutated Genes Show Distinct Cytomorphological Features

Acral melanoma occurring on the palms, soles, and nails is the most common subtype of cutaneous melanoma in Asians. Genetic alterations in acral melanoma and acral melanocytic nevus are not well known. We performed next-generation sequencing and evaluated the correlations between genetic information and the clinicopathologic characteristics from 85 Korean patients with acral melanocytic neoplasms. Of the 64 patients with acral melanoma, most had lesions at the T2 stage or higher, and the heel was the most common anatomical site of melanoma (n = 34 [53.1%]). The five most common mutations were BRAF (22 [34.4%]), NRAS (14, [21.9%]), NF1 (11, [17.2%]), GNAQ (12, [17.2%]), and KIT (7, [10.9%]). In the 21 acral melanocytic nevi, those five gene mutations were also common. Copy number variations were also frequently detected in 75% of acral melanomas and 47.6% of acral melanocytic nevi, and amplification was more common than deletion in both lesions. BRAF mutation was associated with round epithelioid cells and NRAS and NF1 mutations with bizarre cells. NF1 and GNAQ mutations showed elongated and spindle cells with prominent dendrites in acral melanomas. KIT mutations were common in amelanotic acral melanoma. This study suggests that common mutated genes are associated with distinct cytomorphological features in acral melanocytic lesions.

Acral melanoma foot lesions. Part 2: clinical presentation, diagnosis, and management

Acral melanoma (AM) is a rare subtype of cutaneous malignant melanoma found on acral skin, primarily on the soles of the feet. Although rare, it is the most common subtype of melanoma found in patients of African or Asian ethnicity and has a poor prognosis, often because of the more advanced stage of presentation at diagnosis. In the second of this two-part series, we review the clinical presentation, histopathology, diagnosis and management of AM. Clinically, AM presents as a variegated lesion with blue-black pigment and irregular borders on acral skin. A parallel-ridge pattern is a very specific dermoscopic finding for AM. The differential diagnoses of AM include acral naevus, pyoderma gangrenosum, pyogenic granuloma, verrucous carcinoma and peripheral neuropathy-induced foot ulcers. If there is a clinical suspicion of AM, an excisional biopsy should be taken. Once diagnosis is confirmed by histology, surgical excision is the standard treatment. Overall, dermoscopy and histopathology are key tools in the diagnosis of AM. A greater emphasis on melanoma screening and awareness is essential in minority populations to improve survival outcomes in AM.

Acral melanoma foot lesions. Part 1: epidemiology, aetiology, and molecular pathology

Acral melanoma (AM) is a rare subtype of cutaneous malignant melanoma (MM) found on acral skin, primarily on the soles of the feet. Although rare, it is the most common subtype of MM found in patients of African or East Asian ethnicity and has a poor prognosis, often because of the more advanced stage of presentation at diagnosis. The pathogenesis of AM is unclear, but genetic alterations, including mutations in BRAF, NRAS, and KIT have been implicated. Early diagnosis of AM is important for a better prognosis, but its identification is often challenging, leading to easy misdiagnosis. In the first of this two-part review, we review the history, epidemiology, aetiology and molecular pathology of AM; in part 2 we will review diagnosis and management.

KIT Suppresses BRAFV600E-Mutant Melanoma by Attenuating Oncogenic RAS/MAPK Signaling

The receptor tyrosine kinase KIT promotes survival and migration of melanocytes during development, and excessive KIT activity hyperactivates the RAS/MAPK pathway and can drive formation of melanomas, most notably of rare melanomas that occur on volar and mucosal surfaces of the skin. The much larger fraction of melanomas that occur on sun-exposed skin is driven primarily by BRAF- or NRAS-activating mutations, but these melanomas exhibit a surprising loss of KIT expression, which raises the question of whether loss of KIT in these tumors facilitates tumorigenesis. To address this question, we introduced a kit(lf) mutation into a strain of Tg(mitfa:BRAF^V600E); p53(lf) melanoma-prone zebrafish. Melanoma onset was accelerated in kit(lf); Tg(mitfa:BRAF^V600E); p53(lf) fish. Tumors from kit(lf) animals were more invasive and had higher RAS/MAPK pathway activation. KIT knockdown also increased RAS/MAPK pathway activation in a BRAF^V600E-mutant human melanoma cell line. We found that pathway stimulation upstream of BRAF^V600E could paradoxically reduce signaling downstream of BRAF^V600E, and wild-type BRAF was necessary for this effect, suggesting that its activation can dampen oncogenic BRAF^V600E signaling. In vivo, expression of wild-type BRAF delayed melanoma onset, but only in a kit-dependent manner. Together, these results suggest that KIT can activate signaling through wild-type RAF proteins, thus interfering with oncogenic BRAF^V600E-driven melanoma formation. Cancer Res; 77(21); 5820-30. ©2017 AACR.

Mucosal melanoma: clinical, histological and c-kit gene mutational profile of 86 French cases

BACKGROUND

Mucosal melanomas are rare and highly aggressive tumours. Few studies evaluated mucosal melanomas of locations other than the head and neck region, and other than those of the Asian population.

OBJECTIVES

The objective of this study was to analyse the clinical and histological features, as well as the mutational status of c-kit and b-raf gene of mucosal melanoma in any localization in a French series.

METHODS

We investigated clinical (sex, age, performance status, survival, treatment of the patients and lack of pigmentation of the tumours) and histopathological features (ulceration, Breslow's index, mitotic rate), as well as the mutational status of c-kit and b-raf of 86 mucosal melanomas diagnosed in 15 years in four French University Hospitals.

RESULTS

Most melanomas affected women (72%) and the genital region (46.5%). A fifth of melanomas were amelanotic. 81% of melanomas had a Breslow's index ≥1, whereas all glans melanomas, and most vulvar melanomas had a Breslow index ≤1 mm. Overall survival was 54% at 3 years; 11.6% of the 43 tested mucosal melanomas were c-kit-mutated while the 15 tested genital melanomas were not. The c-kit gene mutation did not influence the overall survival. Age ≥ 50, amelanotic type and performance status ≥1 were not poor prognostic factors in our series.

CONCLUSION

This study confirmed that mucosal melanomas are rare and could be difficult to diagnose being often amelanotic and in hidden sites. Most melanomas were thick at the diagnosis, but glans and vulvar melanomas were thinner probably because of their greater visibility. The frequency of the c-kit mutation varied depending on the initial tumour site. In our series, the prognosis was poor, independently from c-kit mutations and the patient's general health and age. The presence of metastasis at diagnosis was associated with a worse prognosis indicating the importance of an early diagnosis.

Clinical report. Acral melanoma in Cambodia: challenges associated with a rare and aggressive disease encountered in a developing country setting

Background: Melanoma is a highly malignant skin cancer. Acral lentiginous melanoma (ALM) is most common among Asians. The prevalence of ALM among melanoma cases in Cambodian is not known.

Objective: To describe the prevalence of ALM among cases of melanoma and the stage of disease at presentation to the health facilities and health providers.

Method: Electronic clinical records were obtained from Children’s Surgical Centre (CSC) database between January 2002 and April 2014. Types and stages melanoma at presentation were documented.

Result: A total of 10 out of 26 melanoma patients had ALM. Their average age at diagnosis was 65.3 years. Most primary lesions were located on the plantar or lateral surfaces of the foot. Most histopathological descriptions were consistent with ALM. Seventy percent had lymph node metastases.

Conclusion: A high proportion of ALM was found associated with trauma as a potential risk factor. Most frequency presented at a late stage of disease. Providers must be made aware of the disease and render appropriate management early for good outcome.

Cutaneous Melanoma in Asians

Malignant melanoma is a rare disease in Asians but potentially the most aggressive form of skin cancer worldwide. It can occur in any melanocyte-containing anatomic site. Four main cutaneous melanoma subtypes are recognized: lentigo maligna melanoma, superficial spreading melanoma, acral lentiginous melanoma (ALM), and nodular melanoma. Generally, excessive exposure to ultraviolet (UV) radiation increases the risk of melanoma. The exception is ALM, which is the most common melanoma subtype in Asians and is not associated with UV radiation. ALM presents as dark brownish to black, irregular maculopatches, nodules, or ulcers on the palms, soles, and nails. The lesions may be misdiagnosed as more benign lesions, such as warts, ulcers, hematomas, foreign bodies, or fungal infections, especially in amelanotic acral melanomas where black pigments are absent. The aim of this brief review is to improve understanding and the rate of early detection thereby reducing mortality, especially regarding cutaneous melanoma in Asians.

Amelanotic Acral Melanoma Associated with KIT Mutation and Vitiligo

Amelanotic acral melanoma is rare and difficult to diagnose, both clinically and pathologically. KIT mutations are frequently found in acral melanomas and are considered a risk factor for poor prognosis. The presence of vitiligo in melanoma has been reported, and KIT is thought to be partly responsible for the dysfunction and loss of melanocytes observed in vitiligo. We report a case of amelanotic subungual melanoma with multiple metastases that was associated with KIT mutation and vitiligo. An 85-year-old man presented with a 3-year history of a tender erythematous ulcerated tumor on the left third fingertip and developed hypopigmented patches on the face and trunk. Histopathological examination of the ulcerative tumor showed aggregates of tumor cells that were pleomorphic epithelioid cells. Immunohistochemical staining of the tumor cells was positive for S100, HMB45, and c-Kit. Histopathological findings from the hypopigmented patch on the face were consistent with vitiligo. Mutation analysis showed a KIT mutation in exon 17 (Y823D). The patient had metastasis to the brain, liver, bone, and both lungs. The patient refused chemotherapy, and died 3 months after the first visit.