Characterization of KIT mutation in melanoma

Background/objectivesRecent studies have shown that the KIT mutational type appears to be a predictive marker for the efficacy of imatinib in treating melanoma. However, a wide range of KIT mutation rates was reported in different types of melanoma, suggesting that the mutation frequency of KIT may be associated with clinicopathological subsets of melanoma.MethodsTo characterize their relationship, we sequenced exons 11, 13, 17, and 18 of KIT in 80 of 85 melanomas collected from two hospitals and categorized KIT mutation by tumor type, age and sex of patients, and mutation hot spots of KIT.ResultsOur results showed that KIT mutation rates were 25%, 22%, and 8% in acral, mucosal, and cutaneous melanomas, respectively. Approximately 38% (5/13) of male patients with acral melanoma and 45% (5/11) of female patients with mucosal melanomas of the anorectal and genitourinary regions had a KIT mutation. Approximately 81% of KIT mutations occurred in L576P, K642E, V559A, and D820Y.ConclusionThis result shows that KIT mutation is enriched in a certain subset of melanoma patients and mutation hot spots do exist.     

Sensitivity and Usefulness of VE1 Immunohistochemical Staining in Acral Melanomas with BRAF Mutation

BackgroundAcral melanomas are known to have a low frequency of BRAF mutation, in contrary to higher KIT mutation. Recently, VE1 immunostaining was reported to have a good correlation with BRAF mutation status.ObjectiveWe aimed to evaluate the clinicopathological features of BRAF-mutated acral melanomas and validate the correlation of the VE1 immunohistochemical stains in those cases.MethodsThe clinical features (age, sex, anatomical site), and histopathological characteristics of 41 patients with acral melanoma were evaluated. We performed a next-generation sequencing to detect BRAF mutation status. We also determined the correlation of VE1 immunohistochemical staining with BRAF mutation status.ResultsAmong 19 acral melanomas with BRAF mutation, common histopathological subtype was acral lentiginous melanoma (8/19, 42%) and nodular melanoma (8/19, 42%) and superficial spreading melanoma (3/19, 16%) followed. VE1 immunostaining results were positive in all 15 cases with BRAF V600E mutation (sensitivity 100%), and negative in 4 cases of BRAF non-V600E mutation. However, VE1 immunostaining was negative in all 22 patients with BRAF wild-type.ConclusionVE1 immunostaining had a good correlation with BRAF V600E mutation status.     

Comparison of Melanoma Subtypes among Korean Patients by Morphologic Features and Ultraviolet Exposure

Background

Genetic alterations have been identified in melanomas according to different levels of sun exposure. Whereas the conventional morphology-based classification provides a clue for tumor growth and prognosis, the new classification by genetic alterations offers a basis for targeted therapy.

Objective

The purpose of this study is to demonstrate the biological behavior of melanoma subtypes and compare the two classifications in the Korean population.

Methods

A retrospective chart review was performed on patients found to have malignant melanoma in Severance Hospital from 2005 to 2012. Age, sex, location of the tumor, histologic subtype, tumor depth, ulceration, lymph node invasion, visceral organ metastasis, and overall survival were evaluated.

Results

Of the 206 cases, the most common type was acral melanoma (n=94, 45.6%), followed by nonchronic sun damage-induced melanoma (n=43, 20.9%), and mucosal melanoma (n=40, 19.4%). Twenty-one patients (10.2%) had the chronic sun-damaged type, whereas eight patients (3.9%) had tumors of unknown primary origin. Lentigo maligna melanoma was newly classified as the chronic sun-damaged type, and acral lentiginous melanoma as the acral type. More than half of the superficial spreading melanomas were newly grouped as nonchronic sun-damaged melanomas, whereas nodular melanoma was rather evenly distributed.

Conclusion

The distribution of melanomas was largely similar in both the morphology-based and sun exposure-based classifications, and in both classifications, mucosal melanoma had the worst 5-year survival owing to its tumor thickness and advanced stage at the time of diagnosis.     

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.     

Novel LRRFIP2-RAF1 fusion identified in an acral melanoma: A review of the literature on melanocytic proliferations with RAF1 fusions and the potential therapeutic implications

A small subset of cutaneous melanomas harbor oncogenic gene fusions, which could potentially serve as therapeutic targets for patients with advanced disease as novel therapies are developed. Fusions involving RAF1 are exceedingly rare in melanocytic neoplasms, occurring in less than 1% of melanomas, and usually arise in tumors that are wild type for BRAF, NRAS, and NF1. We describe herein a case of acral melanoma with two satellite metastases and sentinel lymph node involvement. The melanoma had a concomitant KIT variant and LRRFIP2-RAF1 fusion. This constellation of molecular findings has not been reported previously in melanoma. We review the existing literature on melanocytic neoplasms with RAF1 fusions and discuss the potential clinical implications of this genetic event.     

Frequency of Trauma,Physical Stress,and Occupation in Acral Melanoma: Analysis of 313 Acral Melanoma Patients in Korea

BackgroundTraumatic events are thought to be a cause of acral melanoma. However, little is known about the role of mechanical trauma or physical stress in the development of acral melanoma.ObjectiveIn our study, we evaluated the frequency of trauma, physical stress, and occupation in patients with acral melanoma and aimed to identify any pathological correlates of these factors.MethodsWe conducted a retrospective study of 313 acral melanoma patients from Chonnam National University Hospital. We mapped melanoma-developed anatomical sites of acral areas and assessed patients'' history of trauma, physical stress, and occupation.ResultsAmong the 313 acral melanoma patients, many reported a traumatic event (84 of 313; 26.8%) or physical stress (91 of 313; 29.1%) before the melanoma developed. The most common anatomical sites in these patients were on the borders of the foot (136 of 313; 43.5%). Trauma was more commonly associated with the fingernails and toenails than other sites. The frequency of each type of physical stress depended on the site of the lesion. Farmer and fisherman were the most common occupations (130 of 313; 41.5%) of the acral melanoma patients.ConclusionOur results demonstrate that traumatic events, physical stress, and certain occupations are common in acral melanomas. Further studies are needed to establish whether these are risk factors for acral melanomas.     

Mutational profiling of acral melanomas in Korean populations

The proportion of acral melanoma (AM) is much higher in Asian populations than in Caucasian populations. Although mutational profiles associated with AM have been discovered in Caucasian populations, knowledge of its genetic alterations in Asian populations is limited. To describe the molecular nature of AM in Korean patients, we performed mutational profiling of AM and matched normal tissues in patients. Fifty‐one formalin‐fixed paraffin‐embedded AM samples and 32 matched pairs from patients’ saliva DNA were analysed by next‐generation sequencing. Only mutations confirmed via digital droplet PCR or in BRAF, KIT and NRAS, the most frequently altered cancer genes in cutaneous melanoma, were considered as positive. The relationship between mutational status and clinicopathological features were examined. Of the 47 AM patients screened, alteration of BRAF, NRAS and KIT genes was observed in 6.4%, 4.3% and 8.5%, respectively. We also tested matched normal tissues of patients to identify tumor‐specific mutations. Examination of the mutational profile in a cohort of 28 primary melanomas and matched normal controls found BRAF mutations in two cases (7.1%), KIT mutations in three cases (10.7%) and CTNNB1 mutations in one case (3.6%). The BRAF, NRAS and KIT mutation status did not correlate with clinicopathological characteristics. Our results show that KIT, NRAS and BRAF hotspot mutations occur at a low frequency in Korean populations. We also observed a case with the CTNNB1 mutation, which raises the possibility that other pathways are associated with AM development.     

Distinct MAPK and PI3K pathway mutations in different melanoma types in Taiwanese individuals

Background

A number of studies investigating mutations of genes involved in MAPK and PI3K pathways in melanoma patients have been performed, most of which were based on Caucasian populations.

Objectives

We sought to identify BRAF, NRAS, MEK1, PI3K, and PTEN mutations and further determine possible correlations with clinicopathological parameters in Taiwanese patients with acral, non-chronic sun damaged (NCSD), or mucosal melanoma.

Materials & Methods

Forty melanocytic nevi, 24 dysplastic nevi, and 175 melanomas from Taiwanese patients were analysed for mutations in BRAF, NRAS, MEK1, PI3K, and PTEN genes by PCR and direct sequencing. Immunohistochemical analysis of the respective proteins in nevi and melanomas were also performed to determine possible clinicopathological characteristics.

Results

In addition to the classic BRAF^V600E mutation, a novel BRAF^V600L mutation was identified in acral and sinonasal melanomas. A significantly reduced frequency of NRAS and BRAF mutations was noted compared with Caucasian-based studies. Increased immunohistochemical scores for pan-RAS and MEK1 and less nodal metastasis were associated with enhanced survival rates in acral and NCSD melanoma patients.

Conclusions

Our findings suggest that oncogenic events may differ among melanomas in Asian patients geographically (e.g. between Japanese and Taiwanese patients). Moreover, distinct genetic alterations were noted among acral, NCSD, and mucosal melanoma patients in our study, and the expression of biomarkers correlated with clinical survival rates differentially among the various melanoma groups.

     

Acral cutaneous melanoma in caucasians: clinical features, histopathology and prognosis in 112 patients

BACKGROUND: Acral lentiginous melanoma (ALM) is the fourth distinct variant of cutaneous melanoma. The histological diagnosis and prognosis of ALM are still controversial. OBJECTIVES: To review the features of a large series of patients with ALM, and confirm the validity of the histological criteria for this type of melanoma. METHODS: A collection of 2642 patients with cutaneous melanoma was recorded during the period 1986-97, among these 187 were located on acral sites. Histological specimens were reviewed in 112 acral melanomas; the following study is based on this subgroup. RESULTS: Histological examination revealed acral lentiginous melanomas predominantly in palmoplantar and subungual locations (60%), while superficial spreading melanomas (SSM) were found mainly on the dorsal aspects of hands and feet (30%). Nodular melanomas (NM) (9%) occurred in all acral sites. The histological re-examination confirmed the characteristics of ALM as described by Reed in 1976. With increasing tumour thickness nesting of tumour cells and upward migration to the cornified layer was similarly observed. The 5-year survival rate for patients with primary acral melanoma without recognizable metastasis was 82%. ALM differed significantly in survival from SSM (P = 0.001) and lentigo maligna melanoma (P < 0. 001), but survival rates were similar to NM (P = 0.9). CONCLUSIONS: ALM, as diagnosed by current histological criteria, occur on the palms, soles and subungual sites, and have a poor prognosis.     

Genetic alterations in RAS‐regulated pathway in acral lentiginous melanoma

Studies integrating clinicopathological and genetic features have revealed distinct patterns of genomic aberrations in Melanoma. Distributions of BRAF or NRAS mutations and gains of several oncogenes differ among melanoma subgroups, while 9p21 deletions are found in all melanoma subtypes. In the study, status of genes involved in cell cycle progression and apoptosis was evaluated in a panel of 17 frozen primary acral melanomas. NRAS mutations were found in 17% of the tumors. In contrast, BRAF mutations were not found. Gains of AURKA gene (20q13.3) were detected in 37.5% of samples, gains of CCND1 gene (11q13) or TERT gene (5p15.33) in 31.2% and gains of NRAS gene (1p13.2) in 25%. Alterations in 9p21 were identified in 69% of tumors. Gains of 11q13 and 20q13 were mutually exclusive, and 1p13.2 gain was associated with 5p15.33. Our findings showed that alterations in RAS‐related pathways are present in 87.5% of acral lentiginous melanomas.     

BRAF mutations might be more common than supposed in vulvar melanomas

Data on BRAF, NRAS and KIT mutations are scarce in patients with vulvo‐vaginal melanomas and are associated with important therapeutic issues. We investigated their prevalence in a cohort of patients with female lower genital tract melanomas between 2003 and 2017. Of the 22 patients, 5 (22.7%) harboured a BRAF mutation, which was much higher than the rate of 5% reported in the literature. One patient, who was tested negative on the primary melanoma, had a NRAS mutation in a cutaneous metastasis. Our data provide a rationale for prospective and repeated mutations testing in female lower genital tract melanomas.     

Consumption of the epidermis in acral lentiginous melanoma

Background: Consumption of the epidermis (hereafter, consumption), namely thinning of the epidermis with attenuation of basal and suprabasal layers and loss of rete ridges adjacent to collections of melanocytes, has been used to differentiate invasive melanoma from Spitz nevi. Evaluation of 213 invasive melanomas, including only two cases of acral lentiginous melanoma (ALM), showed that the frequency of consumption increases with increasing tumor thickness. Methods: We evaluated consumption in 52 acral melanomas relative to age, gender, Breslow depth, tumor thickness (based on the 2010 American Joint Commission on Cancer guidelines), Clark level, mitoses, ulceration, vertical‐growth phase, regression, tumor‐infiltrating lymphocytes and anatomical site. Results: Consumption was more frequent in ALM with increasing Breslow depth (p = 0.01), and in the presence of ulceration (p = 0.0078); in all cases with ulcer, consumption was found adjacent to the ulceration. There was no statistically significant difference in consumption in nail melanomas in comparison to melanomas of acral skin other than the nail. Conclusions: These results support the hypothesis that epidermal thinning in consumption represents an early phase of ulceration. No statistically significant difference in consumption was found between nail melanomas and melanomas of acral skin other than the nail, probably because of similar tumor thickness in both groups. Ohata C, Nakai C, Kasugai T, Katayama I. Consumption of the epidermis in acral lentiginous melanoma.     

Constitutive activation of the mitogen-activated protein kinase signaling pathway in acral melanomas

One of the most attractive clinical targets for melanoma is the mitogen-activated protein kinase (MAPK) signaling pathway. In this study, we examined MAPK signaling activation in a total of 28 acral melanoma samples, consisting of 13 primary tumors and 15 metastases. In line with the previous reports, NRAS/BRAF mutations were rare; only one metastatic tumor had an NRAS E61R mutation, and one primary tumor and two metastases harbored BRAF V599E mutations. Western blot analyses, however, revealed phosphorylated extracellular signal-regulated kinase (ERK)1/2 proteins in 11 of 14 (78.5%) of the acral melanoma tumors. Furthermore, fluorescence in situ hybridization analyses revealed the prominent amplification of the cyclin D1 (CCND1) gene, which is an important down-stream effecter of the MAPK pathway, in 5 of 21 (23.8%) tumors examined. Interestingly, two of three tumors that were negative for phosphorylated ERK proteins according to western blot harbored CCND1 amplifications, suggesting that the increased gene dosage of CCND1 may exert effects similar to phosphorylated ERK proteins in cell growth. We conclude that, despite the low frequency of BRAF/NRAS mutations, the MAPK signaling pathway is constitutively activated in the majority of acral melanomas. This provides a rational basis to include acral melanomas into the clinical trials with MAPK inhibitors.     

BRAF,KIT and NRAS mutations and expression of c‐KIT,phosphorylated extracellular signal‐regulated kinase and phosphorylated AKT in Japanese melanoma patients

To clarify the status of gene mutation and activation of growth signal in melanoma of Japanese patients in vivo, we analyzed the mutation of BRAF exon 15, NRAS exon 2, and KIT exons 9, 11, 13, 17 and 18 in melanoma cells obtained by laser capture microdissection, and performed direct sequencing in 20 cases of acral lentiginous melanoma (ALM) and 17 cases of superficial spreading melanoma (SSM). In the study of the mutation of BRAF, pyrosequencing was also done. To examine the cell proliferation signaling, immunohistochemistry for phosphorylated extracellular signal‐regulated kinase (pERK), phosphorylated AKT (phosphorylated AKT) and c‐KIT was done. The mutation of BRAF p.V600E was detected in 13 cases of ALM (65.0%) and 12 cases of SSM (70.6%). No NRAS mutation was found in all cases. The mutation in exons 9, 11, and 18 of KIT was detected in nine cases. The mutation of BRAF and KIT showed no correlation with clinical stage, lymph node metastasis, tumor thickness, ulceration and histology. pERK and pAKT was observed in small population of melanoma cells and there was no correlation with gene mutation. Our results indicate that the mutations of BRAF and KIT exist in Japanese melanoma patients, however, the cell growth signaling may be regulated by not only these mutated genes, but by other unknown regulatory factors, which may affect the prognosis of melanoma.     

Oncogenetics of melanoma: basis for molecular diagnostics and therapy

Our understanding of oncogenetics and of the molecular mechanisms involved in melanoma development and signaling has dramatically changed in recent years. Today, melanomas are also classified based on molecular alterations. Emerging molecular therapies are targeted against specific mutations in melanoma. An example of targeted therapies is the successful treatment of KIT‐mutant melanoma with the kinase inhibitor imatinib. Highly selective BRAF‐inhibitors are likewise under clinical development and show encouraging clinical responses. An increasing number of targeted drugs will emerge in the coming years, based on molecular diagnostics and classification. The present article reviews signaling pathways in melanocytes and alterations in melanoma that are a prerequisite to understanding modern cancer therapies in melanoma.     

Efficacy of combined radiotherapy and anti‐programmed death 1 therapy in acral and mucosal melanoma

Some studies showed that clinical response to immune check point inhibitors is lower in acral and mucosal melanoma than in cutaneous melanoma. Although the synergistic effect of radiotherapy (RT) and ipilimumab has been reported in patients with brain metastasis, the efficacy of combined RT and anti‐programmed death 1 (PD‐1) therapy for acral and mucosal melanoma is unclear. The present study aimed to evaluate the efficacy of combined RT and anti‐PD‐1 therapy for acral and mucosal melanoma. We retrospectively analyzed patients with acral or mucosal melanoma who were treated with anti‐PD‐1 and RT at Sapporo Medical University Hospital. In 10 patients (acral, 3; mucosal, 7), the response rate (RR) and the disease control rate (DCR) were 40% and 60%, respectively. As regards mucosal melanoma, four of the seven patients had achieved complete response + partial response, and three had progressive disease (RR = 57.1%). Meanwhile, two of the three patients with acral melanoma had stable disease and one had progressive disease (RR and DCR were 0% and 66.6%, respectively). Except for the patients treated with palliative RT for bone metastasis in the present study, the RR was 50% (4/8 patients), and the DCR was 75% (6/8 patients). Vitiligo developed after RT in five (50%) patients at a median duration of 2 months after RT. The clinical response and the high occurrence of vitiligo suggest that the combination of RT and anti‐PD‐1 therapy could be effective in some patients with mucosal melanoma.     

Is the survival rate for acral melanoma actually worse than other cutaneous melanomas?

It is still not clear whether the survival rate for acral melanoma (AM) is better or worse than that of cutaneous melanoma developed at other sites. We sought to evaluate the difference in survival depending on the primary tumor site of cutaneous melanoma. We retrospectively reviewed primary cutaneous melanoma cases diagnosed at Samsung Medical Center, a tertiary institution in Korea, from January 1995 to July 2017. The cohort consisted of 642 patients, with 389 non-acral cutaneous melanoma (NACM) patients and 253 AM patients. The AM patients had a higher percentage of stage 0 diagnoses than the NACM patients (31.6% vs 6.9%, respectively). The factors associated with overall survival were primary tumor site, sex, age, American Joint Committee on Cancer stage, surgery and medical treatment (P < 0.05). Non-acral sites showed worse survival in multivariable analysis (hazard ratio [HR], 1.457; 95% confidence interval [CI], 1.051–2.020; P = 0.0240). Among the NACM, melanomas on the trunk were associated with a higher risk of mortality compared with AM (HR, 1.883; 95% CI, 1.142–3.107; P = 0.0131). Acral melanoma was associated with a better prognosis than non-acral melanoma, specifically when located on the trunk, in Korean patients.     

Expression of soluble adenylyl cyclase in acral melanomas

Soluble adenylyl cyclase (sAC) regulates melanocytic cells, and is a diagnostic marker for pigmented skin lesions. Because only a few studies on sAC expression in acral melanomas have been performed, we investigated the histopathological significance of sAC expression in 33 cases of acral melanoma, and assessed its diagnostic value in distinguishing melanoma in situ (MIS, n = 17) from acral invasive melanomas (n = 16) and melanocytic naevi (n = 11). Acral melanomas exhibited more marked nuclear immunopositivity compared with acral melanocytic naevi. sAC expression significantly correlated with the nuclear morphology of melanocytes and melanoma cells, namely, hyperchromatic nuclei and prominent nucleoli within vesicular nuclei. sAC expression was predominantly observed in the hyperchromatic nuclei of MIS and the prominent nucleoli invasive melanomas, respectively. In vitro culture models of melanocytes and melanoma cell lines exhibited sAC staining patterns similar to those of acral melanomas. Differentiation induction showed that nuclear and nucleolar expression varied depending on cell morphology. sAC immunostaining may be useful for the differential diagnosis of acral melanocytic lesions, and sAC expressed in the nucleus and nucleolus might be related to cytological and nuclear changes associated with invasion and progression of acral melanomas.     

BRAF V600E mutation as a prognostic factor in cutaneous melanoma patients

The prognostic significance of BRAF mutations in the natural course of melanoma is controversial. The aim of study was to assess the prognostic significance of BRAF V600E mutation in cutaneous melanoma patients. A total of 151 melanomas were included in the study. BRAF V600E mutation was detected using the real‐time PCR. BRAF V600E mutation rate was 51%. BRAF mutation rate was higher for young patients (61.4%) and upper limbs (63.2%), trunk (59.3%) and head and neck (59.2%) were the most frequently afflicted sites in BRAF‐mutant patients, whereas lower limbs were mostly affected in BRAF‐wild patients (77.8%). Likewise, acral melanomas rarely harbored BRAF mutation (17.1%). The disease‐free survivals regarding the entire and Stage III cohorts were longer in the BRAF‐mutant group than in the BRAF‐wild group (p = .006 and p = .004, respectively), whereas Stage I–II patients had no survival differences between BRAF statuses (p = .2). Likewise, BRAF‐mutant patients had better overall survival (OS) time compared to BRAF‐wild patients in all stages (p = .01), in Stage III (p = .01), and in Stage IV patients (p = .001). However, no differences between BRAF statuses were observed in Stage I–II melanomas (p = .3). In conclusion, BRAF V600E‐mutant melanomas show favorable prognostic impact on both disease‐free and OSs in all staged melanomas except local disease.     

Expression of Phosphatase and Tensin Homologue,phospho-Akt,and p53 in Acral Benign and Malignant Melanocytic Neoplasms (Benign Nevi,Dysplastic Nevi,and Acral Melanomas)

BackgroundThe role of the phosphatidylinositol-3 kinase signaling pathway in the development of acral melanoma has recently gained evidence. Phosphatase and tensin homologue (PTEN), one of the key molecules in the pathway, acts as a tumor suppressor through either an Akt-dependent or Akt-independent pathway. Akt accelerates degradation of p53.ObjectiveWe assessed the expression of PTEN, phospho-Akt (p-Akt), and p53 by immunohistochemistry in benign acral nevi, acral dysplastic nevi, and acral melanomas in the radial growth phase and with a vertical growth component.MethodsTen specimens in each group were included. Paraffin-embedded specimens were immunostained with antibodies for PTEN, p-Akt, and p53. We scored both the staining intensity and the proportion of positive cells. The final score was calculated by multiplying the intensity score by the proportion score.ResultsAll specimens of benign acral nevi except one showed some degree of PTEN-negative cells. The numbers of p-Akt and p53-positive cells were higher in acral dysplastic nevi and melanoma than in benign nevi. P-Akt scores were 1.7, 1.8, 2.6, and 4.4, and p53 scores were 2.0, 2.1, 3.8, and 4.1 in each group. PTEN and p-Akt scores in advanced acral melanoma were higher than in the other neoplasms.ConclusionThe expression of PTEN was decreased and the expression of p-Akt was increased in acral melanoma, especially in advanced cases. The PTEN-induced pathway appears to affect the late stage of melanomagenesis. Altered expression of p-Akt is thought to be due to secondary changes following the loss of PTEN.