Spatial transcriptomic analysis of amelanotic acral melanoma versus pigmented acral melanoma reveals distinct molecular determinants.

BACKGROUND: Amelanotic acral melanoma (AAM) is a rare type of acral melanoma that has a poor prognosis. OBJECTIVES: To investigate the transcriptomic differences between AAM and pigmented acral melanoma (PAM). METHODS: Differences in the spatially resolved transcriptomic profiles of 9 patients with AAM with 29 regions of interest (ROIs) and 11 patients with PAM with 46 ROIs were investigated using S100b and CD3 morphology markers. RESULTS: In S100b+ tumour cell areas, we detected 11 upregulated differentially expressed genes (DEGs; including chaperone/ubiquitin--associated DEGs) and 82 downregulated DEGs (including human leucocyte antigen) in AAMs vs. PAMs. Protein-protein interaction network and pathway analyses revealed significant enrichment of dysregulated translational and nonsense-mediated decay pathways but significant decreases in antigen processing and presentation, interferon signalling and melanin biosynthesis pathways in S100b+ ROIs of AAMs compared with PAMs. In tumour-associated immune cell areas, the numbers of CD8 T cells (P = 0.04) and M1 macrophages (P = 0.01) were significantly decreased, whereas those of monocytes (P = 0.04) and endothelial cells (P = 0.04) were increased in AAMs compared with PAMs. CONCLUSIONS: These findings could widen our understanding of the biological differences between AAMs and PAMs, which might result in a different clinical course.

Melanoma is one of the most serious types of skin cancer. As melanoma starts in cells that produce melanin (the substance that produces hair, eye and skin colouration), melanoma tumours are usually brown or black. 'Amelanotic melanoma' is a subtype of melanoma that has little or no melanin pigmentation. Less than 2% of melanomas are amelanotic melanomas. 'Acral melanoma' is a type of melanoma that occurs on the hands and feet. In acral melanoma, the lack of pigmentation has been associated with worse outcomes for patients. Why amelanotic acral melanoma (or 'AAM') has a worse prognosis than pigmented acral melanoma (or 'PAM') is unclear. Using a type of technology called 'spatial transcriptomic analysis', we analysed a type of nucleic acid called RNA in 9 people with AAM and 11 with PAM. Seventy-five 'regions of interest' were selected. These regions of interest are known to be associated with tumour cells or immune cells around tumours. We found that pathways involved in making proteins (translation) and in a process that removes faulty proteins called 'messenger RNA' were more active in AAM. However, pathways involved in processing and presenting antigens (substances that can trigger an immune response), the signalling of other proteins called 'interferons' and melanin production were less active in AAM. The number of specific types of white blood cells that recognize and attack tumours were decreased, whereas other cell types such as cells that line blood vessels were increased in AAM. Our findings could increase our understanding of the differences between AAMs and PAMs. This may lead to an improvement in prognosis.

Clinicopathological, dermoscopic features and circumstances of diagnosis of amelanotic or hypomelanotic melanoma: A prospective multicentric study in the French private medical sector.

BACKGROUND: Amelanotic or hypomelanotic melanomas (AHM) are difficult to diagnose, and are often diagnosed late, with a high Breslow index and a poor prognosis. PATIENTS AND METHODS: A total of 226 volunteer dermatologists consulting in private practice in France completed an online form for each new histologically proven case of melanoma diagnosed at their clinic in 2020. This anonymised survey collected data on the clinical, dermoscopic, and histological features of melanoma, as well as the circumstances of diagnosis and initial management. A group of 145 AHM was single out and compared to the 1503 pigmented melanomas (PM) from the same cohort. RESULTS: 1503 pigmented melanomas (PM) and 145 AHM (8.8% of these melanomas) were identified and included. In the AHM group, the mean age at diagnosis was 65 ±â€¯16 years, with no significant difference from the PM control group. AHM were not predominantly on the face and neck area, and there were no differences based on gender. Warning signs (local progression and bleeding) were significantly more frequent in the AHM group than in the PM group. AHM were more frequently ulcerated and nodular, with a higher median Breslow thickness than in the PM group (1.56 vs. 0.5 mm), and mitoses were more frequent. Dermoscopy was widely used and proved useful for distinguishing benign lesions, and for highlighting the vascular polymorphous pattern of malignant lesions. Patients noticed the suspicious lesion themselves in most cases of AHM (73.2%), as opposed to their general practitioner (17.2%) or entourage (9.5%). A total body skin examination enabled detection of 19.3% of AHM and 21.3% of PM where the patient consulted for another lesion, or for an unrelated reason. CONCLUSION: AHM are difficult to diagnose for the clinician because of the paucity or absence of pigmentary criteria. Knowledge of dermoscopic vascular patterns is critical and could help reduce the median Breslow index of AHM at the time of detection. Self-examination of the skin should be encouraged, and simple algorithms for earlier detection of skin cancers should be promoted among health professionals and the general population.

A Rare Case of Primary Vulval Amelanotic Melanoma Involving the Urethra.

A 60-year-old woman came to the Emergency Department complaining of a vaginal formation. The urologist suspected a urethral caruncle: the patient was discharged with vaginal oestrogen cream to relieve symptoms and a follow-up was suggested. After two months the patient returned to the Emergency Department since the mass was increasing in volume and complaining of dysuria and haematuria. Ultrasound, contrast-enhanced computed tomography, and contrast-enhanced magnetic resonance revealed a mass arising from the mucosa and involving the vulva and the urethra, suspicious of malignancy. We present a challenging diagnosis of an infiltrative and rapidly progressive primary vulval amelanotic melanoma with a complete imaging evaluation and a confirmed histological diagnosis.

Thin Amelanotic and Hypomelanotic Melanoma: Clinicopathological and Dermoscopic Features.

Background and Objectives: Amelanotic/hypomelanotic melanomas (AHMs) account for 2-8% of all cutaneous melanomas. Due to their clinical appearance and the lack of specific dermoscopic indicators, AHMs are challenging to diagnose, particularly in thinner cutaneous lesions. The aim of our study was to evaluate the clinicopathological and dermoscopic features of thin AHMs. Identifying the baseline clinical-pathological features and dermoscopic aspects of thin AHMs is crucial to better understand this entity. Materials and Methods: We divided the AHM cohort into two groups based on Breslow thickness: thin (≤1.00 mm) and thick (>1.00 mm). This stratification helped identify any significant clinicopathological differences between the groups. For dermoscopic analysis, we employed the "pattern analysis" approach, which involves a simultaneous and subjective assessment of different criteria. Results: Out of the 2.800 melanomas analyzed for Breslow thickness, 153 were identified as AHMs. Among these, 65 patients presented with thin AHMs and 88 with thick AHMs. Red hair color and phototype II were more prevalent in patients with thin AHMs. The trunk was the most common anatomic site for thin AHMs. Patients with thin AHMs showed a higher number of multiple melanomas. Dermoscopic analysis revealed no significant difference between thin AHMs and thick AHMs, except for a more frequent occurrence of residual reticulum in thin AHMs. Conclusions: Thin AHMs typically affect individuals with lower phototypes and red hair color. These aspects can be related to the higher presence of pheomelanin, which provides limited protection against sun damage. This also correlates with the fact that the trunk, a site commonly exposed to intermittent sun exposure, is the primary anatomical location for thin AHMs. Multiple primary melanomas are more common in patients with thin AHMs, likely due to an intrinsic predisposition as well as greater periodic dermatologic follow-ups in this class of patients. Apart from the presence of residual reticulum, no other significant dermoscopic differences were observed, complicating the differential diagnosis between thin and thick AHMs based on dermoscopy alone.

Primary vulvar melanoma in an adolescent patient.

Herein we describe the case of a Black adolescent who was found to have widely metastatic melanoma originating from a primary vulvar lesion. The lesion presented as a pink, vegetative nodule of the clitoral hood which grew in size over several years and was confirmed to be melanoma on shave biopsy. This patient's amelanotic presentation in conjunction with the rare incidence of vulvar melanoma contributed to the delay in diagnosis. This case exemplifies the challenge of early recognition of potentially malignant vulvar lesions for primary care providers in adolescents.

Multifocal primary amelanotic meningeal melanomas mimicking lymphoma: a case report and literature review.

Primary meningeal melanoma is a rare type of melanocytic cancer originating from the melanocytes of the leptomeninges. It commonly presents as a solitary mass, and multifocal amelanotic lesions were scarcely reported. Diagnosis of multifocal melanoma is particularly challenging, clinically and diagnostically, especially in the absence of cutaneous nevi and melanin pigment. Surgical biopsy result is the gold standard. In this case study, we present an uncommon case of multifocal primary amelanotic meningeal melanomas mimicking lymphomas in the skull base and near the Sylvian fissure, which serves to provide reference value to the clinical diagnosis. Physicians should be aware of the existence of this special type in the clinical work.

Primary amelanotic melanoma of anorectum - a rare case report with diagnostic challenge.

Anorectal melanoma is an exceptionally rare and aggressive form of cancer. One per cent of anorectal malignant tumours are anorectal malignant melanomas, which are exceedingly uncommon. We report a case of a 47-year-old woman who experienced painless rectal bleeding. On examination, an irregular lump was seen in the posterior rectal wall, measuring 4 × 3.7 cm. Biopsies were obtained under endoscopic guidance for histomorphology and immunohistochemistry. The biopsy examination showed nests of tumour mass in the lamina and muscularis mucosae. The tumour mass was composed of round to oval cells having enlarged nuclei, conspicuous nucleoli, and a scant amount of cytoplasm. No melanin pigmentation was noted in the tumour cells. HMB-45, S-100, and vimentin were all detected by immunohistochemistry. A definitive diagnosis of amelanotic malignant melanoma was rendered. The patient underwent abdominoperineal resection with a hysterectomy and bilateral salpingo-oophorectomy. Anorectal melanoma presents with bleeding per rectum and is often misdiagnosed as internal haemorrhoids or adenocarcinoma clinically. Amelanotic melanoma, which lacks melanin pigment, is difficult to diagnose. Patients who appear with rectal bleeding should have a malignant melanoma evaluation as a possible differential diagnosis, and suitable diagnostic procedures, such as a colonoscopy and a biopsy with immunohistochemistry, should be carried out to arrive at a conclusive diagnosis.

Amelanotic metastatic gastric malignant melanoma: a case report.

Melanoma is a malignant form of cutaneous cancer with an increasing incidence since 1970s, accounting for nearly 75% of the death related to skin cancer especially in western countries. Highest recurrence and mortality were observed for the subtype with distal metastasis, demonstrating poor outcomes. However, high incidence of gastrointestinal metastasis of malignant melanoma is frequently misdiagnosed due to lack of specific clinical manifestations, especially for the rare observed cases presented amelanotic appearance, accounting for about 2% of all metastatic cases. In the present study, we reported a 36-year-old male patient, who was firstly diagnosed as gastric cancer, and then was confirmed as amelanotic melanoma metastasis by pathological examination, demonstrating positive for melanoma markers including Melan A, S-100, Hmb45 and CD79a. In conclusion, for the amelanotic neoplasm observed during gastroscopy in patients with melanoma history, pathological examination should be carried out to confirm the possibility of melanoma metastasis, providing evidences for the following treatment.

E-Cadherin Expression in Canine Melanocytic Tumors: Histological, Immunohistochemical, and Survival Analysis.

E-cadherin, a glycoprotein involved in cell-cell adhesion, has a pivotal role in epithelial-mesenchymal transition, a process through which neoplastic epithelial cells develop an invasive phenotype. In human cutaneous melanomas, decreased E-cadherin expression is associated with shorter survival and increased Breslow thickness, whereas in the dog its role is poorly understood. Tumor thickness and modified Clark level were recently proposed as useful features to assess canine melanocytic tumors, but no studies investigated their association with E-cadherin expression. We performed immunohistochemistry on 77 formalin-fixed, paraffin-embedded primary canine melanocytic tumors. A 3-tier and a 2-tier classification system for assessing E-cadherin expression were tested, with the latter being more informative for the assessment of canine melanocytic tumors. E-cadherin expression was lower in cutaneous melanomas than melanocytomas, as well as in amelanotic tumors compared to pigmented tumors. In amelanotic melanomas, absent E-cadherin expression was associated with an unfavorable outcome, suggesting a potential use of this marker in defining the prognosis of amelanotic melanomas. E-cadherin expression was lower in tumors with greater tumor thickness and modified Clark level ≥IV, suggesting its possible utility in identifying the most invasive tumors. The expression of E-cadherin in oral melanomas was heterogeneous, but was associated with pigmentation and clinical outcome; thus, E-cadherin evaluation could be advantageous to detect the most aggressive neoplasms. However, cutaneous melanomas without E-cadherin expression frequently had a favorable clinical outcome. Hence, its importance as prognostic factor should be carefully considered depending on the tumor origin.

Clinicopathological characteristics and prognosis of amelanotic acral melanoma: A comparative study with pigmented acral melanoma.

We compared the clinicopathological features and prognosis between 16 amelanotic acral melanomas versus 56 pigmented acral melanomas. Amelanotic acral melanomas showed a thicker Breslow thickness (all had a Breslow thickness > 1 mm), more frequent ulceration (15/16, 93.7%) and lower HMB-45 positive rate than pigmented acral melanomas. However, a significant difference in survival was not observed.

Sinonasal amelanotic melanoma with neuroendocrine differentiation: a diagnostic conundrum.

Mucosal malignant melanoma of the head and neck (HN) is a rare and aggressive neoplasm which constitutes only 1% of all melanomas. Neuroendocrine differentiation is an extremely unusual phenomenon in mucosal melanomas, of which five cases have been reported. We report a rare case of a 63-year-old female who developed sinonasal amelanotic melanoma with immunohistochemical expression of neuroendocrine markers, presenting a diagnostic dilemma. Ultrastructural evidence of melanosomes and neurosecretory granules aided in arriving at the diagnosis. Aberrant immunoexpression of neuroendocrine markers, particularly in an amelanotic melanoma, has critical diagnostic implications, as various malignancies with undifferentiated histomorphology occur at this site, many of which stain positively with neuroendocrine markers. We discuss the differential diagnoses and recommend a high index of suspicion so as not to miss the diagnosis of mucosal melanoma at this location.

Cytotoxic Effect of Vanicosides A and B from Reynoutria sachalinensis Against Melanotic and Amelanotic Melanoma Cell Lines and in silico Evaluation for Inhibition of BRAFV600E and MEK1.

Vanicosides A and B are the esters of hydroxycinnamic acids with sucrose, occurring in a few plant species from the Polygonaceae family. So far, vanicosides A and B have not been evaluated for anticancer activity against human malignant melanoma. In this study, we tested these two natural products, isolated from Reynoutria sachalinensis rhizomes, against two human melanoma cell lines (amelanotic C32 cell line and melanotic A375 cell line, both bearing endogenous BRAFV600E mutation) and two normal human cell lines-keratinocytes (HaCaT) and the primary fibroblast line. Additionally, a molecular docking of vanicoside A and vanicoside B with selected targets involved in melanoma progression was performed. Cell viability was studied using an MTT assay. A RealTime-Glo™ Annexin V Apoptosis and Necrosis assay was used for monitoring programmed cell death (PCD). Vanicoside A demonstrated strong cytotoxicity against the amelanotic C32 cell line (viability of the C32 cell line was decreased to 55% after 72 h incubation with 5.0 µM of vanicoside A), significantly stronger than vanicoside B. This stronger cytotoxic activity can be attributed to an additional acetyl group in vanicoside A. No significant differences in the cytotoxicity of vanicosides were observed against the less sensitive A375 cell line. Moreover, vanicosides caused the death of melanoma cells at concentrations from 2.5 to 50 µM, without harming the primary fibroblast line. The keratinocyte cell line (HaCaT) was more sensitive to vanicosides than fibroblasts, showing a clear decrease in viability after incubation with 25 µM of vanicoside A as well as a significant phosphatidylserine (PS) exposure, but without a measurable cell death-associated fluorescence. Vanicosides induced an apoptotic death pathway in melanoma cell lines, but because of the initial loss of cell membrane integrity, an additional cell death mechanism might be involved like permeability transition pore (PTP)-mediated necrosis that needs to be explored in the future. Molecular docking indicated that both compounds bind to the active site of the BRAFV600E kinase and MEK-1 kinase; further experiments on their specific inhibitory activity of these targets should be considered.

Amelanotic melanoma in a patient with oculocutaneous albinism.

Oculocutaneous albinism is a genetically heterogeneous, autosomal recessive group of disorders characterized by a generalized decreased or absence of melanin pigment in the eyes, hair, and skin. These patients have a greater sensitivity to UV radiation and a predisposition to skin tumors, mainly squamous cell carcinoma and basal cell carcinomas, and to a lesser extent malignant melanomas. Melanoma can be one of the most challenging cancers to diagnose in patients with albinism. We report an uncommon clinical presentation of melanoma, an amelanotic melanoma in the right supraciliar region in a patient with oculocutaneous albinism. The clinical presentation was an erythematous, scaly and ill-defined plaque. The skin biopsy revealed a lentigo maligna melanoma. Amelanotic melanomas are one of the two most difficult to diagnose subtypes of melanoma, together with the nevoid type. Melanoma in oculocutaneous albinism patients are often amelanotic, which makes their clinical diagnosis very difficult. These patients should be examined in the dermatology department at least once a year and it is recommended to have a high index of suspicion.

Promotion of TRAIL/Apo2L-induced apoptosis by low-dose interferon-ß in human malignant melanoma cells.

Interferon ß (IFN-ß) is considered a signaling molecule with important therapeutic potential in cancer since IFN-ß-induced gene transcription mediates antiproliferation and cell death induction. Whereas, TNF-related apoptosis inducing ligand/Apo2 ligand (TRAIL/Apo2L) has emerged as a promising anticancer agent because it induces apoptosis specifically in cancer cells. In this study, we elucidated that IFN-ß augments TRAIL-induced apoptosis synergistically using five human malignant melanoma cells. All of these cells were induced apoptosis by TRAIL. Whereas, the response against IFN-ß was different in amelanotic cells (A375 and CRL1579) and melanotic cells (G361, SK-MEL-28, and MeWo). The responsibility of amelanotic cells against IFN-ß was higher than those of melanotic cells. The synergism of IFN-ß and TRAIL were correlated with the responsibilities of the cells against IFN-ß. The synergistic interaction was confirmed by a combination index based on the Chou-Talalay method. The upregulation of apoptosis in amelanotic cells was caused by very low doses of IFN-ß (over 0.1 IU/ml). Both of p53-mediated intrinsic pathway and Fas-related extrinsic pathway were activated by IFN-ß alone and combination with TRAIL. Further, TRAIL death receptors (DR4 and DR5) were upregulated by a low-dose IFN-ß (over 0.1 IU/ml) and the expression was more promoted by the combination with TRAIL. It was clarified that the upregulation of DR5 is associated with the declination of viability.

Clinicopathologic, misdiagnosis, and survival differences between clinically amelanotic melanomas and pigmented melanomas.

BACKGROUND: Amelanotic malignant melanoma (AMM) is challenging to diagnose. Clinical risk factors for AMM are not well defined. OBJECTIVE: To investigate clinicopathologic, misdiagnosis, and survival differences between patients with AMM and those with pigmented malignant melanoma (PMM). METHODS: A cross-sectional retrospective medical record review at a tertiary academic medical center. RESULTS: A total of 933 patients with melanoma with known presenting tumor color were identified (342 with AMM vs 591 with PMM). AMM was associated with older age, history of nonmelanoma skin cancer, and red hair, whereas AMM was inversely associated with a family history of melanoma, more than 50 nevi, and a history of dysplastic nevi. Compared with PMM, AMM was more likely to be located on the head and/or neck, had more aggressive pathologic features (greater Breslow depth and/or mitoses, ulceration, nodular subtype), and was less likely to be associated with a precursor nevus or regression. Finally, patients with AMM were more likely to be misdiagnosed than were patients with PMM (25% vs 12% clinically and 12% vs 7% pathologically), and they had poorer melanoma-specific survival (5-year overall survival rate, 0.77 [95% confidence interval, 0.72-0.82] vs 0.84 [95% confidence interval, 0.80-0.87]). LIMITATIONS: Retrospective study design, single-institutional study. CONCLUSION: Greater clinician awareness, lower biopsy thresholds, and increased patient education may be useful to enhance AMM detection in patients with certain characteristics.

A pink enlarging plaque on the plantar foot: amelanotic acral lentiginous melanoma.

Acral lentiginous melanomas account for less than 5% of all melanomas, whereas amelanotic melanomas account for around 2-8% of all melanomas. Amelanotic acral lentiginous melanomas are even less common and can often be mistaken for other clinical entities, including pyogenic granulomas, non-melanoma skin cancers, and warts. We describe a man in his 50s with a twenty-year history of a skin-colored plaque on the right plantar foot; after enlargement and failure of wart treatment, a shave biopsy revealed an amelanotic melanoma. A subsequent wide local excision and sentinel lymph node biopsy revealed melanoma in 4 lymph nodes and the patient underwent an abbreviated course of interferon-alpha therapy. The patient remained stable until 2 ? years after diagnosis, at which time he presented with in-transit metastases on the foot and right thigh; he has since been stable on nivolumab. This case represents the challenge of diagnosing amelanotic melanomas on acral surfaces and highlights the importance of considering a skin biopsy for diagnosis of any changing, atypical amelanotic lesions on the feet or hands.

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.