Oral melanoacanthoma: Clinicopathological and immunohistochemical features of a case series and a scoping review.

BACKGROUND: This study presents a case series and scoping review of oral melanoacanthoma to examine its clinical, histopathological, and immunohistochemical characteristics. METHODS: Nine cases of oral melanoacanthoma were included in the case series. Clinical data were collected from biopsy charts. Hematoxylin-eosin and immunohistochemistry for TRP2, CD3, and CD20 were done. For the scoping review, MEDLINE/PubMed, Web of Science, EMBASE, and Scopus were searched. RESULTS: Case series: The mean age was 46.8 years (female-to-male ratio 2:1). Lesion's mean size was 11.0 mm (±9.3). Lesions were mainly macular (77.8%) with brown or black coloration (88.9%) and often affected multiple sites (44.4%). The evolution time ranged from 15 days to 96 months. Lesions commonly showed epithelial acanthosis (66.7%), spongiosis (55.6%), exocytosis (77.8%), melanin incontinence (88.9%), and inflammatory infiltrate in the lamina propria (77.8%), from which all showed lymphocytes. TRP2-positive melanocytes were identified in the basal and spinous layer of all cases, and in the superficial layer of three cases. CD3-positive cells predominate over the CD20-positive. Scoping review: 85 cases of oral melanoacanthoma were retrieved from 55 studies. Patients were primarily female (female-to-male ratio 2.2:1), black-skinned (64.1%), with a mean age of 36.13 (± 17.24). Lesions were flat (81.9%), often brown (62.4%). Buccal mucosa was the preferred site (32.9%), followed by multiple sites (28.2%). CONCLUSION: Oral melanoacanthoma mainly affects women across a wide age range, with lesions commonly appearing as brown/black macules, particularly on the buccal mucosa. TRP2-positive melanocytes and T-lymphocytes were consistently found and could participate in oral melanoacanthoma pathogenesis.

Vitamin D Receptor and Retinoid X Receptor Alpha in Melanocytic Benign Lesions and Melanoma.

ABSTRACT: Vitamin D receptor (VDR) exerts its biological effects when it heterodimerizes to a nuclear receptor of the retinoid family called retinoid X receptor α (RXRα), stimulating or inhibiting DNA transcription. VDR stimulation by vitamin D analogs led to in vitro antiproliferative effects, and experimental RXRα knockout led to loss of proliferation control in melanoma cells. The aim of this study was to determine VDR and RXRα positivity in melanocytic lesions, compared with normal skin species. By immunohistochemistry assays, nuclear VDR, cytoplasmic VDR, and RXRα and RXRα in keratinocytes surrounding melanocytes were evaluated in 77 controls, 92 intradermal nevi, 54 dysplastic nevi, and 83 melanomas in this retrospective cross-sectional study. Nuclear VDR, cytoplasmic VDR, and RXRα were less expressed in exposed areas ( P < 0.001, P = 0.0006, and P < 0.001, respectively) than covered areas. All melanocytic lesions had loss of VDR and RXRα comparing with the control group. In the melanoma group, nuclear VDR tended to inversely correlate with the Breslow index (r = -0.11, P = 0.29) but directly correlated with histological regression ( P = 0.0293). RXRα inversely correlated with mitosis (r = -0.245; P = 0.0263). We can suggest that sun exposure affected VDR and RXRα immunopositivity. Nuclear VDR tendency of inverse correlation with the Breslow index showed that worse melanomas have a greater loss of VDR. RXRα inversely correlated with mitosis, indicating that RXRα can have a role in proliferation control. VDR and RXRα may participate in the development of melanocytic lesions and be a future target of new studies and directed therapies.

Impact of second histopathological review of melanocytic skin lesions at a melanoma reference center in Brazil.

BACKGROUND: After the biopsy of a suspicious melanocytic lesion, patients depend on the pathologist's precision of specimen evaluation. METHODS: We assessed the agreement between histopathological reports made by general pathologists and reviewed by a dermatopathologist to evaluate the impact on the patient's management. RESULTS: In 79 cases analyzed, underdiagnosis was observed in 21.6% and overdiagnosis in 17.7%, resulting in changes in the patients' conduct. The assessment of the Clark level, ulceration and histological type showed mild agreement (P<0.001); the Breslow thickness, surgical margin, and staging showed moderate agreement (P<0.001). CONCLUSIONS: A dermatopathologist's review should be incorporated into the routine of reference services for pigmented lesions.

Experimental approaches to assess melanocytes mosaicism in segmental vitiligo.

Vitiligo is an autoimmune disease of the skin that results in localized or disseminated white macules. One common feature of several existing classification protocols is the distribution of the disease into two main subtypes, non-segmental vitiligo (NSV) and segmental vitiligo (SV). SV is characterized by depigmentation spreading within one or more skin segments while NSV is widespread. Several clinical-epidemiological observations suggest that SV has distinct autoimmune pathophysiology compared to NSV. Furthermore, the clinical distribution pattern of SV lesions closely resembles other melanocyte mosaicism diseases. These observations led us to hypothesize that SV is caused by a localized autoimmune reaction targeting epidermal mosaicism melanocytes. Here, we proposed examples of experimental approaches to assess mosaicism in SV patients.

Update on the pathogenesis of vitiligo.

Vitiligo is a complex disease whose pathogenesis results from the interaction of genetic components, metabolic factors linked to cellular oxidative stress, melanocyte adhesion to the epithelium, and immunity (innate and adaptive), which culminate in aggression against melanocytes. In vitiligo, melanocytes are more sensitive to oxidative damage, leading to the increased expression of proinflammatory proteins such as HSP70. The lower expression of epithelial adhesion molecules, such as DDR1 and E-cadherin, facilitates damage to melanocytes and exposure of antigens that favor autoimmunity. Activation of the type 1-IFN pathway perpetuates the direct action of CD8+ cells against melanocytes, facilitated by regulatory T-cell dysfunction. The identification of several genes involved in these processes sets the stage for disease development and maintenance. However, the relationship of vitiligo with environmental factors, psychological stress, comorbidities, and the elements that define individual susceptibility to the disease are a challenge to the integration of theories related to its pathogenesis.

Genome-wide promoter methylation profiling in a cellular model of melanoma progression reveals markers of malignancy and metastasis that predict melanoma survival.

The epigenetic changes associated with melanoma progression to advanced and metastatic stages are still poorly understood. To shed light on the CpG methylation dynamics during melanoma development, we analyzed the methylome profiles of a four-stage cell line model of melanoma progression: non-tumorigenic melanocytes (melan-a), premalignant melanocytes (4C), non-metastatic melanoma cells (4C11-), and metastatic melanoma cells (4C11+). We identified 540 hypo- and 37 hypermethylated gene promoters that together characterized a malignancy signature, and 646 hypo- and 520 hypermethylated promoters that distinguished a metastasis signature. Differentially methylated genes from these signatures were correlated with overall survival using TCGA-SKCM methylation data. Moreover, multivariate Cox analyses with LASSO regularization identified panels of 33 and 31 CpGs, respectively, from the malignancy and metastasis signatures that predicted poor survival. We found a concordant relationship between DNA methylation and transcriptional levels for genes from the malignancy (Pyroxd2 and Ptgfrn) and metastasis (Arnt2, Igfbp4 and Ptprf) signatures, which were both also correlated with melanoma prognosis. Altogether, this study reveals novel CpGs methylation markers associated with malignancy and metastasis that collectively could improve the survival prediction of melanoma patients.

The Role of Reflectance Confocal Microscopy in the Evaluation of Pigmented Oral Lesions and Their Relationship With Histopathological Aspects.

ABSTRACT: Oral pigmentations are a heterogeneous group and can be the result of physiological activity of oral mucosal melanocytes, secondary to exogenous causes, associated with systemic or local diseases, or due to proliferative activity of melanocytes. Their diagnosis is critical because these lesions can be markers of internal diseases or, in the case of melanocytic proliferative processes, they may represent a malignant neoplasm. In the past decade, the use of reflectance confocal microscopy, a noninvasive imaging tool, has aided the analysis of such lesions, but the establishment of firm criteria in their evaluation is still lacking. This study evaluated a series of 19 cases of pigmented oral lesions and correlated the reflectance confocal microscopy findings with histopathological classical criteria. We found 13 cases of melanotic macule, 1 of them associated with Peutz-Jeghers syndrome and 2 with Laugier-Hunzinker syndrome; 1 melanocytic nevus; 2 lentigo maligna; 2 pigmented actinic cheilitis; and 1 case of postinflammatory pigmentation secondary to a lupus erythematosus oral discoid lesion. The main difference between benign and malignant lesions was the presence of atypical proliferation in lentigo maligna. Langerhans cells with thick dendritic processes, which may be present in other benign and inflammatory pigmentations is one of the main reasons for diagnostic pitfalls.

Treatment of recalcitrant vitiligo by autologous non-cultured and trypsinized melanocyte grafting in the west of Iran.

BACKGROUND: Vitiligo is a common disease with a high burden, and its recalcitrant type is unresponsive to current medical treatments. Autologous non-cultured and trypsinized melanocyte grafting, which is a simple and experience-based procedure, has been suggested for the treatment of vitiligo. OBJECTIVE: To assess autologous non-cultured and trypsinised melanocyte grafting in recalcitrant vitiligo. METHODS: This clinical trial was done on 28 patients (20 females and 8 males). After demarcation and preparation of both donor and recipient sites, both sites were shaved by a curette. The materials harvested from the donor site were trypsinized and centrifuged. The resulting suspension was mixed with hyaluronic acid gel and was spread over the shaved recipient area. RESULTS: Twenty-eight patients with a total of 108 lesions and a mean age of 25.93 ± 7.11 years were included in the present study. Generalized vitiligo (57.1%) was the most common clinical type and the face and neck regions (38%) were the most frequent treated sites. Good to excellent repigmentation was seen in the face and neck, trunk, upper extremity, and genitals in 31 (57.4%), 11 (20.4%), 9 (16.7%) and 3 (5.5%) patients, respectively. Face and neck showed significantly better results (p < 0.05). STUDY LIMITATIONS: Low sample size and single-center study. CONCLUSION: Autologous non-cultured and trypsinized melanocyte grafting is a safe method with satisfactory outcomes in recalcitrant vitiligo. Appropriate training of physicians and proper use of specialists' experiences can be effective in increasing the improvement rate.

Genes regulated by DNA methylation are involved in distinct phenotypes during melanoma progression and are prognostic factors for patients.

In addition to mutations, epigenetic alterations are important contributors to malignant transformation and tumor progression. The aim of this work was to identify epigenetic events in which promoter or gene body DNA methylation induces gene expression changes that drive melanocyte malignant transformation and metastasis. We previously developed a linear mouse model of melanoma progression consisting of spontaneously immortalized melanocytes, premalignant melanocytes, a nonmetastatic tumorigenic, and a metastatic cell line. Here, through the integrative analysis of methylome and transcriptome data, we identified the relationship between promoter and/or gene body DNA methylation alterations and gene expression in early, intermediate, and late stages of melanoma progression. We identified adenylate cyclase type 3 (Adcy3) and inositol polyphosphate 4-phosphatase type II (Inpp4b), which affect tumor growth and metastatic potential, respectively. Importantly, the gene expression and DNA methylation profiles found in this murine model of melanoma progression were correlated with available clinical data from large population-based primary melanoma cohorts, revealing potential prognostic markers.

Follicular Melanocytes in Frontal Fibrosing Alopecia: An Immunohistochemical Study With Trichoscopic Correlation.

BACKGROUND: Frontal fibrosing alopecia (FFA) is a scarring alopecia that affects the frontotemporal hairline. Clinically, it may develop with cutaneous hypopigmentation of the affected areas, which has been associated with a reduction in the epidermal melanocyte count. In trichoscopy, peripilar white halos can be observed, which have been associated with fibrosis in other scarring alopecias. OBJECTIVE: To evaluate the trichoscopic, histopathological and immunohistochemical characteristics of the peripilar white halos in FFA patients. MATERIALS AND METHODS: We conducted a descriptive cross-sectional study that included 12 patients with FFA presenting peripilar white halos. Two 2-mm punch trichoscopy-guided biopsies were performed in all patients, one fragment for vertical section and another for horizontal section. The vertical sections were stained with Fontana-Mason and Melan-A. RESULTS: On trichoscopic examination, peripilar white halos ≤ 1 mm in size were observed on the affected scalp. In vertical sections, a reduction in basal melanin pigmentation and a decrease in the melanocyte count in the upper segment of the hair follicle were observed with Fontana-Masson staining and Melan-A immunostaining, respectively. LIMITATIONS: The small sample size and absence of a control group. CONCLUSION: This study shows follicular melanocyte involvement in FFA, and this finding may be associated with the peripilar white halos observed in trichoscopy.

Melanomas em cães no Sertão do Nordeste do Brasil - epidemiologia, fatores de risco e achados clinicopatológicos / Melanoma in dogs in the backlands of Northeastern Brazil - epidemiology, risk factors and clinicopathological findings

Background: Melanoma is a malignant neoplasm that arises from melanocytes and malanoblasts. It is also more frequently reported in dogs than in other species. They may arise from melanocytes in the skin, on the surfaces of the mucous membranes, and eyes. The aim of this study was to describe the epidemiological aspects, risk factors and clinicopathological findings of melanoma in dogs in the backlands, northeastern Brazil. Materials, Methods & Results: A retrospective study was carried out in all biopsy samples and necropsy examinations of dogs, from January 2003 to December 2021, at the Animal Pathology Laboratory of the Federal University of Campina Grande, Patos, Paraiba, northeastern Brazil. Epidemiological data, clinical signs, and gross lesions were reviewed from the diagnostic laboratory reports. Samples of the skin, lymph nodes, central nervous system and organs of the thoracic and abdominal cavities were fixed in 10% buffered formalin, processed routinely for histopathology, embedded in paraffin wax, cut into 4 µm sections, and stained with hematoxylin and eosin (HE). Histological sections were also submitted to immunohistochemistry with the primary antibody anti-Melan A. Of the 4717 records found, 1158 (24.5%) were diagnosed with neoplasms, of which 48 (4.14%) cases were of melanoma. Of this total, 28 (58.3%) dogs were elderly, 19 (39.6%) were adults, and 1 (2.1%) was young. Mixed breed animals were the most affected (42.6%), followed by the pinscher breed (19.1%). According to the anatomical region, the most affected site was the skin (38/53=71.7%), followed by the oral cavity (12/53=22.65%) and the eyes (3/53=5.7%). Grossly, the skin lesions were characterized by exophytic and usually blackened, sometimes irregular and firm, nodules. At cut, they had a smooth, compact and blackened surface. Lesions in the oral cavity were characterized by blackened, irregular and infiltrating nodules or masses. The ocular lesions were always unilateral and were characterized by an enlarged and diffusely blackened eyeball, with areas of ulceration and subversion of tissue architecture. In 5 animals there was more than one anatomical site affected, totaling 53 lesions. In 9 (17%) cases, metastases were identified, 8 in regional lymph nodes and 1 in the lung. Histopathology showed a densely non-encapsulated, poorly delimited, expansive and infiltrative neoplasm, composed of neoplastic cells arranged in islands or nests and supported by fibrovascular stroma, containing a variable amount of brownish pigment (melanin). Immunohistochemistry showed strong immunostaining of the neoplastic cells in brown by the anti-Melan A antibody. Discussion: The diagnosis of melanoma was established based on epidemiological, clinical, anatomopathological, and immunohistochemical findings. Gender is not a predisposing factor, and although there was no statistically significant relationship, males were more affected. Senescence is a conditioning risk factor. Elderly animals were more affected (P < 0.0001) than adult ones, with OR = 4.38; and young ones (P = 0.0051), with OR = 12.65. Some breeds, especially those with marked skin pigmentation, were more affected, however the most affected ones in this survey were pinscher and poodle. Cutaneous melanoma accounted for almost 72% of cases, contesting recent studies where oral cavity melanoma was more frequent. Therefore, it is believed that the climatic conditions of the backlands sub-region, in northeastern Brazil, associated with the individual characteristics of the dogs, are involved in the development of these neoplasms, since the climate is predominantly dry, with high temperatures throughout the year, with maximums that can reach 40ºC, favoring the exposure to high incidence of ultraviolet radiation.

Transcriptional signatures underlying dynamic phenotypic switching and novel disease biomarkers in a linear cellular model of melanoma progression.

Despite advances in therapeutics, the progression of melanoma to metastasis still confers a poor outcome to patients. Nevertheless, there is a scarcity of biological models to understand cellular and molecular changes taking place along disease progression. Here, we characterized the transcriptome profiles of a multi-stage murine model of melanoma progression comprising a nontumorigenic melanocyte lineage (melan-a), premalignant melanocytes (4C), nonmetastatic (4C11-) and metastasis-prone (4C11+) melanoma cells. Clustering analyses have grouped the 4 cell lines according to their differentiated (melan-a and 4C11+) or undifferentiated/"mesenchymal-like" (4C and 4C11-) morphologies, suggesting dynamic gene expression patterns associated with the transition between these phenotypes. The cell plasticity observed in the murine melanoma progression model was corroborated by molecular markers described during stepwise human melanoma differentiation, as the differentiated cell lines in our model exhibit upregulation of transitory and melanocytic markers, whereas "mesenchymal-like" cells show increased expression of undifferentiated and neural crest-like markers. Sets of differentially expressed genes (DEGs) were detected at each transition step of tumor progression, and transcriptional signatures related to malignancy, metastasis and epithelial-to-mesenchymal transition were identified. Finally, DEGs were mapped to their human orthologs and evaluated in uni- and multivariate survival analyses using gene expression and clinical data of 703 drug-naïve primary melanoma patients, revealing several independent candidate prognostic markers. Altogether, these results provide novel insights into the molecular mechanisms underlying the phenotypic switch taking place during melanoma progression, reveal potential drug targets and prognostic biomarkers, and corroborate the translational relevance of this unique sequential model of melanoma progression.

Inflammatory infiltrates in melanocytic lesions / Infiltrados inflamatorios en lesiones melanocíticas

SUMMARY: Inflammatory infiltrates are frequently present in melanocytic lesions, with different distribution and composition. Much attention has been devoted to tumor-infiltrating lymphocytes (TIL) in the tumor microenvironment, establishing their prognostic and predictive value in many malignancies, including melanoma. However, lymphocytes, albeit the most numerous and consistent presence, constitute only part of the immune microenvironment. Other inflammatory cells, including neutrophils, plasma cells, eosinophils and mast cells, are found in melanoma and other melanocytic lesions.Few studies offer a detailed count of these inflammatory infiltrates across the spectrum of melanocytic lesions. By using whole slide image analysis and open source software, in the present study we report the enumeration of different inflammatory infiltrates in benign melanocytic nevi, dysplastic nevi, melanoma in situ and invasive malignant melanomas. Significant higher numbers of plasma cells and neutrophils were observed in melanoma. These results indicate that composition of the inflammatory infiltrate may contribute to the diagnostic algorithm of melanocytic lesions.

RESUMEN: Los infiltrados inflamatorios están presentes con frecuencia en las lesiones melanocíticas, con diferente distribución y composición. Se ha prestado mucha atención a los linfocitos infiltrantes de tumores (TIL) en el microambiente tumoral, estableciendo su valor pronóstico y predictivo en muchas neoplasias malignas, incluido el melanoma. Sin embargo, los linfocitos de presencia más numerosa y constante, constituyen solo una parte del microambiente inmunológico. Otras células inflamatorias, incluidos neutrófilos, células plasmáticas, eosinófilos y mastocitos, se encuentran en el melanoma y otras lesiones melanocíticas. Pocos estudios ofrecen un recuento detallado de estos infiltrados inflamatorios en todo el espectro de lesiones melanocíticas. Mediante el uso de análisis de imágenes de diapositivas completas y software de código abierto, en el presente estudio informamos la enumeración de diferentes infiltrados inflamatorios en nevos melanocíticos benignos, nevos displásicos, melanoma in situ y melanomas malignos invasivos. Se observaron números significativamente más altos de células plasmáticas y neutrófilos en el melanoma. Estos resultados indican que la composición del infiltrado inflamatorio puede contribuir al algoritmo diagnóstico de las lesiones melanocíticas.

Acral lentiginous melanoma: Basic facts, biological characteristics and research perspectives of an understudied disease.

Acral lentiginous melanoma is a histological subtype of cutaneous melanoma that occurs in the glabrous skin of the palms, soles and the nail unit. Although in some countries, particularly in Latin America, Africa and Asia, it represents the most frequently diagnosed subtype of the disease, it only represents a small proportion of melanoma cases in European-descent populations, which is partially why it has not been studied to the same extent as other forms of melanoma. As a result, its unique genomic drivers remain comparatively poorly explored, as well as its causes, with current evidence supporting a UV-independent path to tumorigenesis. In this review, we discuss current knowledge of the aetiology and diagnostic criteria of acral lentiginous melanoma, as well as its epidemiological and histopathological characteristics. We also describe what is known about the genomic landscape of this disease and review the available biological models to explore potential therapeutic targets.

Intraoral atypical lentiginous melanocytic lesion in a pediatric patient.

We present a rare case of intraoral atypical lentiginous melanocytic lesion affecting a pediatric patient, in which the diagnosis of lentiginous junctional melanocytic nevus with cytologic atypia was favored. The main differential diagnosis is lentiginous melanoma, which is a slowly progressing lesion, affecting mainly older adults, and microscopically presenting lentiginous growth pattern of moderately atypical melanocytes, with focal nesting and pagetoid spread. It is strongly recommended that melanocytic lesions showing features of atypical lentiginous growth pattern should be treated with wide excision; however, the impact of these guidelines on pediatric patients needs to be better defined with the report of further cases.

SMARCA4 promotes benign skin malignant transformation into melanoma through Adherens junction signal transduction.

PURPOSE: Melanoma is a malignant skin tumor, and its incidence is rising. To explore the specific differences in benign and malignant melanoma at the genetic level, we performed a series of bioinformatics analyses, including differential gene analysis, co-expression analysis, enrichment analysis, and regulatory prediction. METHODS: The microarray data of benign and malignant melanocytes were downloaded from GEO, and 1917 differential genes were obtained by differential analysis (p < 0.05). Weighted gene co-expression network analysis obtained three functional barrier modules. The essential genes of each module are SMARTA4, HECA, and C1R. RESULTS: The results of the enrichment analysis showed that the dysfunctional module gene was mainly associated with RNA splicing and Adherens junction. Through the pivotal analysis of ncRNA, it was found that miR-448, miR-152-3p, and miR-302b-3p essentially regulate three modules, which we consider to be critical regulators. In the pivot analysis of TF, more control modules include ARID3A, E2F1, E2F3, and E2F8. CONCLUSIONS: We believe that the regulator (miR-448, miR-152-3p, miR-302b-3p) regulates the expression of the core gene SMARCA4, which in turn affects the signal transduction of the Adherens junction. It eventually leads to the deterioration of benign skin spasms into melanoma.

Defining the Histopathological Term Atypical Intraepidermal Melanocytic Proliferation: A Retrospective Cross-Sectional Study.

BACKGROUND: Atypical intraepidermal melanocytic proliferation (AIMP) is a general term assigned to melanocytic proliferations of uncertain biological potential when a definitive histopathological diagnosis cannot be achieved. There are few data available describing the possibility of malignancy of AIMP, or ways to further define diagnosis. OBJECTIVE: To determine the rate of diagnostic change of AIMP to melanoma or melanoma in situ (MIS) after conventional excision. In addition, to determine the role of immunohistochemistry (IHC) in defining AIMP biopsies. METHODS: Retrospective cross-sectional, single-center review of biopsies with a diagnosis of AIMP with a follow-up conventional excision from 2012-2016 was performed. In a separate analysis, a search was performed for AIMP biopsied lesions in which IHC was subsequently performed. RESULTS: The rate of diagnostic change of AIMP to MIS was 4.8% (8/167) after excision. Punch biopsy was a risk factor for diagnostic change to MIS (odds ratio 12.94, confidence interval 2.56-65.38, P = 0.008). The rate of diagnostic change of AIMP biopsies after examining with IHC was 21.3% (34/160) to MIS and 4.4% (7/160) to melanoma. CONCLUSION: The possibility of malignancy of AIMP lesions must be taken into consideration when counseling patients and when planning treatment options. IHC is a useful tool and should be used in the evaluation of AIMP specimens.