Acral Melanocytic Nevi Research Articles

Anatomic mapping of acral melanocytic nevi and acral lentiginous melanomas among Taiwanese patients: A retrospective cohort study

The early diagnosis of acral lentiginous melanoma (ALM) contributes to clinical outcomes since ALM can be mistaken for acral melanocytic nevus (AMN). ALM occurrence is reported to correlate with stress-bearing areas, which may assist in differential diagnoses. Our objective is to evaluate the distribution patterns of ALMs and AMNs on the palms and soles among Taiwanese patients. A retrospective analysis was performed by reviewing the charts of 1400 patients diagnosed with benign and malignant pigmented lesions confirmed after excisional biopsy at our institution between 2000 and 2022 in Taiwan. Correlations between lesions and clinicopathological factors were analyzed. 309 AMNs and 177 ALMs were included. Mechanical stress was significantly associated with plantar ALMs (weight-bearing area: 92.65%, arch: 7.35%, P<0.001). Significant differences in the distribution patterns were observed for plantar ALMs compared with all AMNs (P<0.001) and non-atypical AMNs (P<0.001), but were not observed between palmar AMNs and ALMs. Plantar ALMs were most commonly observed on the weight-bearing areas of the soles, distinct from the distribution of all AMNs and of non-atypical AMNs. The distribution features and anatomic mapping of ALMs may facilitate the early clinical diagnosis of ALM.

Acral Melanocytic Nevi in a High-Risk Population: Prevalence, Clinical Characteristics and Dermatoscopic Patterns

Background: The prevalence of acral nevi and their dermatoscopic patterns have been mainly studied in Asian populations. Few data exist on the prevalence and clinico-dermatoscopic morphology of acral nevi in white populations. Objectives: The aim of this study was to assess the prevalence of acral nevi and evaluate their features in a cohort of Caucasian individuals at high risk for skin cancer. Methods: We prospectively examined the palms and soles of 680 high-risk patients who underwent total body clinical and dermatoscopic documentation, as a part of their routine follow-up, between January 2016 and March 2020 at a skin cancer referral center in Greece. Results: Overall, 334 acral lesions were detected in 217 (37.0%) of 585 patients in the study. The presence of acral nevi was associated with 2.6 higher odds of a total nevus count higher than 50 (OR: 2.6, p < 0.05, confidence intervals [CI]: 1.11–6.09). Of 334 acral nevi, 65.0% were clinically flat and 35.0% were clinically palpable. Palpable lesion had 19-fold higher probability of being located on the sole (OR: 19.44, p < 0.05, CI: 3.91–96.7). The parallel furrow pattern was present in 147 lesions (44.0%). In 76 lesions (22.8%), we observed a previously undefined pattern consisting of wavy lines, which was correlated with clinically palpable lesions (p < 0.001). The third most common pattern was homogeneous (10.5%), followed by the fibrillar (8.7%), the lattice-like (7.2%), the reticular (3.6%), and globular (3.3%). Conclusion: We observed a higher prevalence of benign acral melanocytic lesions than expected, probably related to our cohort selection of patients at high risk for developing skin cancer. Our study confirms the previously described dermatoscopic patterns and provides novel insights into the dermatoscopic morphology of acral palpable nevi, for which we described a new benign pattern consisting of wavy lines.

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 subcorneal hematoma: Additional dermoscopic findings differentiating it from acral melanocytic lesions

Background: Acral subcorneal hematoma (ASH) is a dark-colored skin lesion of the palms and/or soles due to bleeding. ASH may be difficult to be clinically differentiated from acral melanocytic lesions, resulting in unnecessary biopsies. Few researches reported the importance of dermoscopy in differentiating ASH from acral melanocytic lesions. Purpose: This study aims at reporting the dermoscopic features in a series of ASH to facilitate precise diagnosis and to avoid performing unnecessary surgical techniques. Methods: Eighteen patients with ASH were studied. Dermoscopic images were obtained using a handheld dermoscope and a dermoscope-adopted phone camera. Paring test was performed on all lesions. Results: The preliminary diagnoses of the lesions were ASH in 55.6%, acral melanocytic nevi in 33.3%, and acral lentiginous melanoma in the remaining 11.1%. Dermoscopically, the lesion colors were red-black in 44.4%, black in 27.8%, and brown in the remaining 27.8%. The pigmentation patterns were homogeneous (structureless) in 55.6%, parallel ridge in 27.8%, and negative pseudonetwork in the remaining 16.6%. Over 44% of the lesions had red and/or brown globular satellites. Peripheral red lines with/without radial extensions were noticed around ASH in 55.6%. Paring led to complete removal of pigmentation in all ASH (100%), with the appearance of post-paring blood-tinged serum in 55.6%. No skin biopsies were performed. Conclusion: Although there is clinical similarity between ASH and acral melanocytic lesions, dermoscopy and paring test can facilitate a precise diagnosis and markedly decrease the need for unnecessary invasive procedures.

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.

Comparison of dermoscopic features between congenital and acquired acral melanocytic nevi in Korean patients.

The dermoscopic patterns of acral melanocytic nevi (AMNs) are crucial in differentiating them from acral melanoma. Several studies have reported the dermoscopic patterns of acquired acral melanocytic nevi (AAMNs). However, few have investigated the dermoscopic patterns of congenital acral melanocytic nevi (CAMNs). To compare the clinical and dermoscopic features of CAMNs and AAMNs. The present study included 43 patients with CAMNs and 40 with AAMNs. We reviewed their medical records as well as their clinical and dermoscopic findings. Congenital acral melanocytic nevis were more asymmetrical than AAMNs (P=0.002) and presented more frequently as comma-shaped (P=0.005). Regarding dermoscopic findings, globular pattern (55.8%) was the most common feature of CAMNs, while parallel furrow pattern (37.5%) was the most common feature of AAMNs. The presence of fibrillar, globular, and parallel ridge patterns, and diffuse multi-component pigmentation differed significantly between the groups (P<0.05). Furthermore, CAMNs showed melanoma-specific dermoscopic patterns, such as parallel ridge (18.6%) and diffuse multi-component pigmentation (25.6%). The dermoscopic patterns of CAMNs and AAMNs differed markedly. In terms of dermoscopic patterns, CAMNs resembled acral melanoma more often than AAMNs did.

Comparison of dermoscopic features between congenital and acquired acral melanocytic nevi in Korean patients

Comparison of dermoscopic features between congenital and acquired acral melanocytic nevi in Korean patients

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.

Age and Anatomical Location-Related Dermoscopic Patterns of 210 Acral Melanocytic Nevi in a Turkish Population.

Dermoscopy is a useful tool for earlier diagnosis and differentiating benign lesions from melanoma. We aim to investigate dermoscopic features of acral nevi, age, and localisation-related findings of these lesions. This was an observational, descriptive study. Patients were retrospectively collected from the Department of Dermatology. The patients with acral nevi were included in the study. Inclusion criteria were Turkish nationality and the presence of at least 1 acral nevus diagnosed both clinically and dermoscopically. Lesions in dorsal and subungual areas were excluded. All nevi were examined by the same dermatologist. The most common dermoscopic patterns were as follows: parallel furrow (87 patients; 41.4%), globular (24 patients; 11.4%), fibrillar (22 patients; 10.5%), combination patterns (19 patients; 9.1%), globulostreak-like (16 patients; 7.6%), lattice-like (15 patients; 7.1%), homogeneous (12 patients; 5.7%), nontypical (8 patients; 3.8%), parallel ridge (4 patients; 1.9%), reticular (2 patients; 1.0%), and crista dotted pattern (1 patient; 0.5%). The parallel furrow pattern was the most common pattern in all localisations. The number of parallel furrow patterns (5 lesions) was equal to the globulostreak-like pattern (5 lesions) on the thenar area. The number of parallel furrow patterns (4 lesions) was equal to the fibrillar pattern (4 lesions) on the heel. Parallel furrow (dotted variants) (11 lesions) and globulostreak-like patterns (5 lesions) were the most common patterns in the pediatric population (0-15 years old). The fibrillar pattern showed a tendency for soles (12 lesions), while a lattice-like pattern was seen more often in the plantar arch (3 lesions). Description of the dermoscopic features of acral nevi is important to improve management and reduce the number of unnecessary excisions. The most common patterns were parallel furrow, globular, and fibrillar in our study. Parallel furrow (dotted variants) and globulostreak-like patterns were the most common patterns in the pediatric population. The fibrillar pattern showed a tendency for soles, while a lattice-like pattern was seen more often on the plantar arch. Therefore, there may be a relation between anatomic localisation, age, and dermoscopic pattern.

Dermoscopic characteristics of congenital acral melanocytic nevi in a newborn: A case report

Dermoscopic characteristics of congenital acral melanocytic nevi in a newborn: A case report

Expression and mutation analysis of the c-kit gene in acral cutaneous malignant melanoma

Objective To analyze the frequency and type of mutations in the c-kit gene, and to measure the expression of c-kit protein in patients with acral malignant melanoma. Methods Skin tissue specimens were collected from the lesions of 115 patients with cutaneous malignant melanoma（CMM）and 30 patients with acral melanocytic nevi, as well as normal skin of 15 healthy human controls. PCR and DNA sequencing were performed to analyze the sequence of the c-kit gene, and immunohistochemical staining was conducted to observe c-kit protein expression in tissue samples. Statistical analysis was done by Chi-square test, Mann-Whitney U test and Spearman's rank correlation test. Results C-kit protein was expressed in 90.3%（84/93）of acral CMM specimens, 81.8%（18/22）of non-acral CMM specimens, and 63.3%（19/30）of acral melanocytic nevus specimens. Among 58 acral invasive CMM specimens, 29 showed strong expression of c-kit protein in tumor cells at the dermal-epidermal junction, 8 showed negative or weak c-kit expression in invasive and infiltrating tumor cells in the dermis. The expression rate of c-kit protein was significantly higher in acral CMM specimens than in acral melanocytic nevus specimens（χ2 = 12.14, P 0.05）. C-kit gene mutations were detected in 4 out of the 115 CMM cases, including L576P mutation in 3 cases and K642E mutation in 1 case. All the 4 patients carrying mutations were diagnosed as acral CMM, and exhibited diffuse and strong expression of c-kit protein. Conclusions The expression of c-kit protein is stronger in acral than in non-acral invasive CMM lesions. All the mutations detected in these cases are common types of c-kit mutations in acral CMM, but the mutation frequency is lower than that reported in foreign literature. Key words: Melanoma; Nevus, pigmented; Proto-oncogene proteins c-kit; Point mutation; C-kit gene

Evaluation of clinical and dermoscopic features of acral melanocytic nevi

Evaluation of clinical and dermoscopic features of acral melanocytic nevi

Comparison of dermatoscopic images of acral lentiginous melanoma and acral melanocytic nevus occurring on body weight-bearing areas.

Background:Because body weight-bearing produces a shift in the horny layer, acral melanocytic nevus on the body weight-bearing area of the sole showed a regular fibrillar pattern (FP) due to slanting of the melanin columns in the horny layer. On the other hand, acral lentiginous melanoma (ALM) on the body weight-bearing area of the sole tended to show irregular fibrillar pattern showing rather structureless pigmentation instead of a parallel ridge pattern, which is due to the shift of the horny layer.Objective:To elucidate the subtle difference between the regular FP of nevus and irregular FP in ALM. Methods:In this study, the dermatoscopic features of five cases of ALM and five cases of acral melanocytic nevus on the weight-bearing area of the sole were compared.Results:All the cases with nevi showed regular FP showing regular distribution of fibrils, whereas all the melanomas showed irregular distribution of fibrils and colors. Fibrils in nevi tended to be clear at the furrows and dim at the ridges. White fibrils corresponding to the eccrine ducts in the horny layer were more often present on the ridges in ALM, which showed negative FP.Conclusion:Differentiating between the regular and irregular FP, including negative FP, might be helpful for the discrimination of melanoma from nevus.

Parallel ridge pattern in dermoscopy in a case of acral melanocytic nevus of the sole

Parallel ridge pattern in dermoscopy in a case of acral melanocytic nevus of the sole

Age-related prevalence of dermatoscopic patterns of acral melanocytic nevi

The objective of this study was to evaluate the relation between age and dermatoscopic features of acral nevi. We evaluated 159 dermatoscopic images of melanocytic nevi from 146 individuals filed at the Dermatoscopy Outpatient Clinic of Tokyo Women’s Medical University Medical Center East between April 2006 and March 2009. All images of melanocytic lesions on acral volar skin that showed a clear-cut dermatoscopic pattern of an acral nevus at the time of initial observation were included. The dermatoscopic patterns of all images were retrospectively examined in a blinded fashion according to the standard dermatoscopic classification criteria for acral melanocytic nevi. Images were classified using 15 structural variants of the parallel furrow pattern. These variants were then re-classified into two groups; the “single” line group and “double” line group. Patients of the double line group (age, 25.5 years) were significantly younger than those of the single line group (32.4 years). There was no significant difference in the age-related predominance between the solid line patterns and dotted line patterns. There was a significant age difference between patients with nevi showing the crista dotted pattern (mean age 24.9 years) and patients with nevi without the crista dotted pattern (mean age 34.6 years). We conclude that the double line variant of the parallel furrow pattern and crista dotted pattern, which probably correspond to the congenital type acral nevus, tend to be more common in young patients.

Dermoscopic Patterns of 158 Acral Melanocytic Nevi in a Latin American Population

BackgroundMelanocytic nevi are frequently found on acral volar skin. Differentiation between nevi and melanoma is essential and sometimes difficult, although dermoscopy has enabled a more specific diagnosis of pigmented lesions. Dermoscopic patterns of lesions on acral volar skin have mostly been described in European and Asian populations. The Latin American population is heterogeneous, and particularly so in the case of Uruguayans, who largely descend from 3 distinct populations. ObjectiveTo describe dermoscopic patterns of acral melanocytic nevi and evaluate their applicability in a Latin American population in Uruguay. Patients and MethodsThis was an observational, descriptive, cross-sectional study conducted by 2 dermatologists from 4 dermatology clinics in Uruguay. Uruguayan patients older than 18 years with acral melanocytic nevi were included. Digital dermoscopic images were captured and jointly analyzed by 2 investigators. ResultsA total of 158 acral volar nevi in 80 patients were analyzed. The most-prevalent pattern was the parallel furrow pattern (51.3% of nevi), followed by the latticelike pattern (13.3%), the homogeneous pattern (12.7%), the globular pattern (9.5%), the fibrillar pattern (7%), the globulostreaklike pattern (3.8%), and the nontypical pattern (2.5%). The reticular and transition patterns were not observed in our population. ConclusionsThe parallel furrow pattern, followed by the latticelike and homogeneous patterns, was the most-prevalent pattern in acral melanocytic nevi in the Uruguayan population. The fibrillar pattern was found exclusively on the soles. No new dermoscopic patterns were observed. The patterns described in Asian and European literature apply to our population.

Dermoscopic Patterns of 158 Acral Melanocytic Nevi in a Latin American Population

BackgroundMelanocytic nevi are frequently found on acral volar skin. Differentiation between nevi and melanoma is essential and sometimes difficult, although dermoscopy has enabled a more specific diagnosis of pigmented lesions. Dermoscopic patterns of lesions on acral volar skin have mostly been described in European and Asian populations. The Latin American population is heterogeneous, and particularly so in the case of Uruguayans, who largely descend from 3 distinct populations. ObjectiveTo describe dermoscopic patterns of acral melanocytic nevi and evaluate their applicability in a Latin American population in Uruguay. Patients and MethodsThis was an observational, descriptive, cross-sectional study conducted by 2 dermatologists from 4 dermatology clinics in Uruguay. Uruguayan patients older than 18 years with acral melanocytic nevi were included. Digital dermoscopic images were captured and jointly analyzed by 2 investigators. ResultsA total of 158 acral volar nevi in 80 patients were analyzed. The most-prevalent pattern was the parallel furrow pattern (51.3% of nevi), followed by the latticelike pattern (13.3%), the homogeneous pattern (12.7%), the globular pattern (9.5%), the fibrillar pattern (7%), the globulostreaklike pattern (3.8%), and the nontypical pattern (2.5%). The reticular and transition patterns were not observed in our population. ConclusionsThe parallel furrow pattern, followed by the latticelike and homogeneous patterns, was the most-prevalent pattern in acral melanocytic nevi in the Uruguayan population. The fibrillar pattern was found exclusively on the soles. No new dermoscopic patterns were observed. The patterns described in Asian and European literature apply to our population.

Acral Melanocytic Nevi: Prevalence and Distribution of Gross Morphologic Features in White and Black Adults

Acral Melanocytic Nevi: Prevalence and Distribution of Gross Morphologic Features in White and Black Adults

Benign Dermoscopic Parallel Ridge Pattern Variants

T HE PARALLEL RIDGE PATTERN (PRP) IS A VOlar dermoscopic pattern that is characterized by an accentuated pigmentation on the ridges of the skin markings, while the furrows are hypopigmented or unpigmented. It has been demonstrated to be highly specific for acral melanoma, and its presence must be considered a warning sign of melanoma. However, rare cases of benign acral melanocytic nevus can exhibit the PRP, as in the edge of the compound melanocytic nevus shown in Figure1A. The acral blue nevus (Figure 1B) usually shows a bluish, quite homogeneous pigmentation involving the ridges. Ethnic pigmentation clinically presents as pigmented macules with a typical PRP on the palms and soles (Figure2A). The multiplicity, bilateral location, and chronicity of the lesions are suggestive of ethnic-type pigmentation. The presentation is similar in Laugier-Hunziker or Peutz-Jeghers syndrome. Ectasic papillary capillaries of acral angioma present as regular red-blue globules along the ridges (Figure 2B). Repetitive microtrauma can cause extravasation of erythrocytes in the cornified layer, with subsequent misleading globular reddish brown pigmentation on the ridges, as seen in Figure 3A, which shows a posttraumatic purpura due to the friction of the fifth finger caused by regular use of the computer mouse. The PRP was also found in subcorneal hematoma. The lesion appears as well-demarcated roundish macule, with reddish brown pigmentation along the ridges (Figure 3B). Deposit of exogenous pigmentation on the ridges, especially in areas where the stratum corneum is thicker, can also simulate melanoma, as shown in Figure 4, with the use of a self-tanning preparation by a woman with localized palmar hyperkeratosis.

Anatomical and histopathological correlates of the dermoscopic patterns seen in melanocytic nevi on the sole: A retrospective study

Anatomical and histopathologic correlates of the unique dermoscopic patterns seen in melanocytic nevi on acral volar skin is yet to be clarified. Our aim was to investigate the relation between the dermoscopic patterns and anatomical and histopathological characteristics of melanocytic nevi on the sole. The precise locations of 298 melanocytic nevi on the sole from 278 patients were retrospectively investigated, with attention paid to each dermoscopic pattern. In addition, 35 nevi showing each typical dermoscopic pattern were excised and evaluated histopathologically. Melanocytic nevi showing the parallel furrow pattern or the fibrillar pattern were located on the portions of the sole with regular parallel skin markings and were not found on the arch areas of the foot. Moreover, a subtle but distinctive difference in the distribution was observed between nevi of the two patterns; the nevi with the fibrillar pattern showed a tendency for the sites directly pressed by the body's weight. Melanocytic nevi of the lattice-like pattern were mostly located on the arch areas. Histopathologically, irrespective of the dermoscopic patterns, nests of nevus cells were mainly located in the epidermal rete ridges underlying the surface sulci. In the nevi with a fibrillar pattern, the cornified layer showed a slanting arrangement, which is considered to be a histopathological background of the fibrillar pattern. Dermoscopic patterns seen in acral melanocytic nevi could be explained by the unique anatomical and histopathological characteristics of the acral skin.