Anorectal and Genital Mucosal Melanoma: Diagnostic Challenges, Current Knowledge and Therapeutic Opportunities of Rare Melanomas

Combination Immunotherapy for Mucosal Melanoma: Molecular Mechanism, Research Status, and Future Directions

OPINION STATEMENT

Mucosal melanoma is a rare and aggressive subtype of melanoma, accounting for 1%-2% of new cases in the United States in 2023, and 20%-30% in China and other Asian countries. Its origin is often occult, with the lack of early clinical features, the absence of actionable driver mutations, and poor response to immunotherapy, all contributing to its poor prognosis. The rarity of this subtype leads to limited awareness and interventions. Furthermore, due to its immune evasion mechanisms, mucosal melanoma shows resistance to traditional immune checkpoint inhibitors. Consequently, new therapeutic strategies are urgently needed to improve patient outcomes. Recent clinical trials have suggested that combination immunotherapy can overcome immune evasion, reduce resistance to treatment, produce synergistic anti-tumor effects, and improve survival. Epidemiological factors and clinical characteristics play significant roles in diagnosis and prognosis, while the mutational landscape influences responses to immunotherapy. This review provides an overview of these aspects and systematically discusses current research on combination therapies and emerging immunotherapy approaches for mucosal melanoma. It also explores potential future directions for treatment, aiming to enhance therapeutic strategies for this rare cancer and improve patient outcomes.

Clinicopathologic Observations on Primary Malignant Melanoma of the Digestive Tract

ObjectiveWe aimed to investigate the clinical features, histopathological characteristics, immunohistochemical profile, diagnostic and differential diagnostic approaches, and treatment strategies for primary malignant melanoma of the digestive tract.MethodsA retrospective analysis was conducted on 21 patients diagnosed with primary malignant melanoma of the digestive tract between January 2011 and July 2024. The clinical, morphological, and immunohistochemical features of these tumors were systematically evaluated.ResultsThe study cohort included 21 patients (age range: 42-90 years; mean age: 64.8 years) diagnosed with primary malignant melanoma of the digestive tract. All patients underwent surgical treatment, with the majority of tumors located in the anorectal region (15/21), followed by the small intestine (4/21) and esophagus (2/21). Histopathological examination revealed nodular proliferation patterns under low magnification. The tumors were predominantly composed of sheets of epithelioid or spindle-shaped cells that exhibited marked pleomorphism. Melanin pigmentation was identified in 11 tumors. High-power microscopic evaluation demonstrated significant cellular polymorphism, with round, vesicular nuclei containing prominent eosinophilic nucleoli. Frequent mitotic figures were observed throughout the specimens. Notably, two tumors exhibited signet-ring cell-like morphology, characterized by cytoplasmic clearing and peripheral nuclear displacement. Analysis of tumor invasion depth revealed that seven tumors infiltrated the submucosa, six tumors infiltrated the muscularis propria, and eight tumors infiltrated the entire wall. Lymph node metastasis was detected in six patients.ConclusionPrimary malignant melanoma of the digestive tract represents a rare malignancy requiring high clinical suspicion. Endoscopic identification of pigmented lesions should prompt consideration of this diagnosis. Definitive diagnosis requires histopathological confirmation through H&E staining supplemented by immunohistochemical markers (eg, S-100, HMB45, melan-A), combined with imaging tests to exclude metastatic lesions from cutaneous or ocular primary sites.

Survival Outcomes in Patients Undergoing Pelvic Exenteration for Pelvic Mucosal Melanomas: Retrospective Single Institution Australian Study

BACKGROUND

Pelvic mucosal melanomas, including anorectal and urogenital melanomas, are rare and aggressive, with a median overall survival of up to 20 months. Pelvic mucosal melanomas behave differently from their cutaneous counterparts and present late with locoregional disease, making pelvic exenteration its only curative surgical option.

OBJECTIVE

This study aimed to evaluate the survival outcomes after pelvic exenteration in pelvic mucosal melanomas at Royal Prince Alfred Hospital.

DESIGN

Retrospective case series from a prospectively collected pelvic exenteration database from October 1994 to November 2023.

SETTING

Royal Prince Alfred Hospital (quaternary institution), Camperdown, New South Wales, Australia.

PATIENTS

Seven patients undergoing pelvic exenteration for pelvic mucosal melanoma.

MAIN OUTCOME MEASURES

Overall survival, disease-free survival, and complication rates.

RESULTS

Of the 7 patients, most were women (n = 5; 71.4%) and had a median age of 65 years (range, 36-79). Five patients (71.4%) underwent pelvic exenteration for primary pelvic mucosal melanoma, 3 of which were anorectal and 2 vaginal melanomas. Two patients (28.6%) had recurrent anorectal melanoma and received neoadjuvant radiotherapy after an initial wide local excision. Three patients (42.9%) required total pelvic exenteration, whereas 2 required a central pelvic exenteration (28.6%). The remaining procedures included central and lateral pelvic exenteration and anterior, central, and lateral pelvic exenteration. The median length of hospital stay was 19.7 days. Five patients had postoperative complications with 1 major complication (Clavien-Dindo grade IIIa). At the completion of the study, there were 4 mortalities. Mean survival was 23.6 months (range, 2-100) with a recurrence rate of 83%. The median time to recurrence was 3 months, despite 6 patients (85.7%) having R0 resections. Distant recurrence, specifically to bone, the lungs, and the liver, was most common.

LIMITATIONS

Small study cohort due to rarity of disease, limiting generalizability.

CONCLUSIONS

Pelvic exenteration for pelvic mucosal melanoma appears to help control local disease as recurrence is most commonly distant or regional. See Video Abstract .

RESULTADOS DE SUPERVIVENCIA EN PACIENTES SOMETIDOS A EXENTERACIN PLVICA POR MELANOMAS DE LA MUCOSA PLVICA ESTUDIO RETROSPECTIVO AUSTRALIANO DE UNA SOLA INSTITUCIN

ANTECEDENTES:Los melanomas de la mucosa pélvica (MM), incluidos los melanomas anorrectales y urogenitales, son raros y agresivos, con una supervivencia global media de hasta 20 meses. Los melanomas de la mucosa pélvica se comportan de manera diferente a sus contrapartes cutáneas y se presentan tardíamente con enfermedad locoregional, lo que hace que la exenteración pélvica (EP) sea su única opción quirúrgica curativa.OBJETIVO:Este estudio tuvo como objetivo evaluar los resultados de supervivencia tras la exenteración pélvica en melanomas de la mucosa pélvica en el Royal Prince Alfred Hospital.DISEÑO:Serie de casos retrospectivos de una base de datos de exenteración pélvica recopilada prospectivamente desde octubre de 1994 hasta noviembre de 2023.ESCENARIO:Royal Prince Alfred Hospital (institución cuaternaria), Camperdown, Nueva Gales del Sur, Australia.PACIENTES:Siete pacientes sometidos a exenteración pélvica por melanoma de la mucosa pélvica.PRINCIPALES MEDIDAS DE RESULTADOS:Supervivencia general, supervivencia libre de enfermedad y tasas de complicaciones.RESULTADOS:De los siete pacientes, la mayoría fueron mujeres (n = 5, 71,4%) y tenían una edad media de 65 años (rango 36-79). Cinco pacientes (71,4%) fueron sometidos a una exenteración pélvica por melanoma primario de la mucosa pélvica; tres de los cuales eran melanomas anorrectales y dos vaginales. Dos pacientes (28,6%) tuvieron melanoma anorrectal recurrente y recibieron radioterapia neoadyuvante después de una escisión local amplia inicial.Tres pacientes (42,9%) requirieron una exenteración pélvica total, mientras que dos requirieron una exenteración pélvica central (28,6%). Los procedimientos restantes fueron una exenteración pélvica central y lateral; junto con una exenteración pélvica anterior, central y lateral. La duración media de la estancia hospitalaria fue de 19,7 días. Cinco pacientes tuvieron complicaciones postoperatorias con una complicación mayor (Clavien-Dindo IIIa). Al finalizar el estudio, hubo cuatro muertes. La supervivencia media fue de 23,6 meses (rango 2-100) con una tasa de recurrencia del 83%. El tiempo medio hasta la recurrencia fue de tres meses, a pesar de que seis pacientes (85,7%) tuvieron resecciones R0. La recurrencia distante, es decir, en hueso, pulmón e hígado fueron la más comúnes.LIMITACIONES:Cohorte de estudio pequeña debido a la rareza de la enfermedad, lo que limita la generalización.CONCLUSIÓN:La exenteración pélvica para el melanoma de la mucosa pélvica parece ayudar a controlar la enfermedad local, ya que la recurrencia es más comúnmente distante o regional. (Traducción-Dr Osvaldo Gauto ).

Mucosal melanoma: Review from a pathologist point of view

Mucosal melanomas (MuM) are rare malignant tumors arising from the epithelia lining the inner mucosal surfaces of the body. Unlike cutaneous melanoma, understanding of MuM is limited among pathologists and clinicians alike, primarily due to rarity of these tumors. MuM are characterized by genetic alterations quite distinct from cutaneous melanomas; however, their causative and promoting factors are unknown. These melanomas are characteristically diagnosed at a later stage due to their occult locations, leading to a worse prognosis. Dedicated staging systems for MuM exist only for sinonasal and conjunctival melanomas. Risk stratification of patients with MuM, particularly those arising from the anogenital area, is challenging. Recent studies have shown that minor modifications of the American Joint Committee on Cancer eighth edition cutaneous melanoma staging system can group patients fairly robustly; however, the proposed T-categorization systems have yet to be validated in larger cohorts. We summarize the demographic, clinical, histopathologic, and molecular features of common subtypes of MuM and highlight the outstanding needs in this field.

Beyond the Scalpel: Advancing Strategic Approaches and Targeted Therapies in Nonexcisable Melanomas

Melanoma in challenging anatomical locations such as the face, acral surfaces, and mucosal areas presents unique hurdles for surgical excision. This review examines alternative nonsurgical treatment modalities in the context of these complexities, addressing the gaps in current guidelines and the varied efficacy of existing therapies. A comprehensive literature search was conducted using PubMed, Embase, and Web of Science databases. The review focuses on peer-reviewed articles discussing nonsurgical treatment options for melanoma in complex anatomical locations. Articles were screened by three independent researchers, ensuring a broad analysis of topical agents, immunotherapies, radiotherapies, and targeted therapies. The review highlights significant advancements in localized treatments such as imiquimod and intralesional therapy with talimogene laherparepvec (T-VEC), which show promise in managing nonexcisable melanomas. BRAF and MEK inhibitors, as well as checkpoint inhibitors targeting CTLA-4 and PD-1/PD-L1 pathways, demonstrate improved survival rates but pose challenges with resistance and systemic side effects. Radiotherapy serves as an adjunctive strategy due to melanoma's inherent radioresistant properties. Despite advancements, there is a notable absence of comprehensive, evidence-based protocols to guide the treatment of melanoma in these critical areas. This paper underscores the need for standardized treatment guidelines that account for the efficacy, side effects, and psychosocial impacts of therapies. Future research should focus on refining existing treatments and exploring innovative modalities to enhance patient outcomes in the management of nonexcisable melanomas. Comprehensive guidelines and long-term efficacy studies are essential to optimize care and improve the quality of life for patients afflicted with melanoma in challenging anatomical locations.

Primary vulval melanoma and genital lichen sclerosus

Background

Lichen sclerosus (LS) is a chronic, inflammatory skin disease with a predilection for the genitalia. Although, the association between squamous cell cancer and genital LS is well established, a link with genital melanoma has not been thoroughly explored. However, we have recently published a case series of penile melanoma where 9/11 (82%) of patients seen over a 10 year period with penile melanoma were retrospectively found to have histological and/or clinical evidence of genital LS on review.

Objectives

The aim of this study was to illuminate further the relationship between vulval melanoma and genital LS by reviewing all the cases managed by our hospital and undertaking a literature review.

Methods

We identified all the cases with a diagnosis of vulval melanoma over a 16-year period (2006-2022) where histology was available. The clinical notes were retrospectively reviewed, and the histological features of all cases were reassessed by two independent mutually 'blinded' histopathologists. We also performed a literature review of genital LS in patients with vulval melanoma.

Results

A total of 11 patients with vulval melanoma were identified for the review. Histopathological review found evidence of genital LS in seven of them (64%). Genital LS was not documented in any of the original histology reports. Clinical notes and letters were available in nine cases. The literature review identified 12 relevant studies with a total of 18 patients. Twelve cases concerned adult women, and six concerned female children.

Conclusion

The presence of genital LS in as high as 64% of our vulval melanoma cases might indicate a causative relationship between genital LS and vulval melanoma. The pathogenesis of vulval melanoma remains largely unknown. Although ultraviolet radiation is an important pathogenic factor for cutaneous melanoma, it cannot be a factor in vulval melanoma. While possible mechanisms behind this association remain unclear, it is possible that chronic inflammation from genital LS leads to melanocytic distress and increased mutagenesis.

Clinicopathological and Molecular Features of Penile Melanoma With a Proposed Staging System

Penile melanomas (PM) are an exceedingly rare subtype of mucosal melanoma (MM), and we reviewed the clinicopathologic features and molecular profile in 8 PMs. The patient ages ranged from 46 to 78 (mean: 62.8) years with involvement on the glans (n=5; 62.5%), penile urethra (n=2; 25%), and foreskin (n=1, 12.5%). Tumor depth ranged from 1.6 to 10.0 (mean: 5.25) mm. Most of the patients underwent partial penectomy (n=6; 75%) and sentinel lymph node (LN) biopsy N=7; 87.5%). Seven patients had metastatic disease at diagnosis, 6 involving LNs and 1 the adrenal gland, and 4 died of disease with a mean follow-up period of 40.5 (2 to 95) months. Five of 7 (71%) cases identified 15 molecular alterations within KIT , CDKN2A , NF1 , PTEN , and APC (n=2 each), and NRAS , MAP3K1 , CDH1 , MSH6 , and TERT (n=1 each). Two cases were not found to harbor genetic aberrations, and 1 case failed testing. In addition, we reviewed the English literature and included 93 cases with a reported depth of invasion and follow-up. A total of 101 PMs were analyzed for prognostic parameters, and the overall survival was significantly worse in patients with LN metastasis (P=0.0008), distant metastasis (P=0.0016), and greater depth of invasion (P=0.0222) based upon T-stage. While T4 conferred substantially worse survival, the delineation of the survival curves between T2 and T3 was less clear, and combining T2+T3 disease had a strong prognostic impact ( P =0.0024). Prognostic parameters used in the staging of cutaneous melanomas may also be used in PMs. An alternative staging system expanding the inclusion criteria for T2 might provide a more accurate prognostic stratification.

Innovations in Rare Gynecologic Cancer: Melanoma, Neuroendocrine, and Low-Grade Serous Ovarian

In the field of gynecologic cancer, low-grade serous ovarian cancer (LGSOC) has been poorly understood and underinvestigated until recently. Similarly, understanding of the distinct properties and therapeutic sensitivities of gynecologic melanoma and cervical neuroendocrine tumors has recently accelerated. For each of these rare cancers, we explore the epidemiology and natural history, discuss the prognosis, diagnostic testing, and contemporary molecular classification, and then deliberate existing and emerging therapeutic strategies. In LGSOC, we focus on the clinical relevance of recent molecular studies that shed light on the importance of mitogen-activated protein kinase (MAPK) pathway gene mutation and chromosome 1 copy-number change on prognosis and MEK inhibitor sensitivity. We also discuss the relative chemoresistance of this disease and the fact that attention is shifting to combinations of molecular therapies such as endocrine agents plus cyclin-dependent kinase 4/6 inhibitors or MEK inhibitors plus FAK inhibitors. Gynecologic tract melanomas harbor a lower frequency of canonical BRAF mutations, and have lower tumor mutational burden and immune cell infiltration than cutaneous melanomas (CMs). As a result, patients with this disease are less likely to respond to BRAF/MEK or immune checkpoint inhibition than patients with CM. Emerging strategies include the combination of antiangiogenic agents with immune checkpoint inhibitors and the use of adoptive cellular therapies. In cervical neuroendocrine cancer, we discuss the use of surgery in early-stage disease, and the uncertainties regarding the role of radiotherapy. We also explore the evidence for chemotherapy and emerging investigational strategies including the use of poly (ADP-ribose) polymerase inhibitors. For all situations, we explore the shared decision-making process with the patient.

Mucosal Melanoma Clinical Management and Prognostic Implications: A Retrospective Cohort Study

Mucosal melanoma (MM) is an uncommon melanoma subtype affecting mucosal surfaces of the head and neck, anorectal region, and vulvovaginal area. We aimed to present our experience at a tertiary-level hospital regarding MM diagnosis, management, monitoring of progression, mutations, and outcome predictors. We performed a registry-based cohort study including MM cases diagnosed from 2012 to 2022 and retrospectively characterized somatic mutations on BRAF, NRAS and c-KIT. We employed Kaplan-Meier curves, log-rank tests, and Cox regression analysis to explore prognostic factors and survival outcomes in a cohort of 35 patients, mainly women (63%) with a median age of 70 years. Predominantly, MM occurred in the vulvovaginal region (48.6%). At diagnosis, 28.6% had lymph node involvement, and 31.4% also had distant metastasis. Mutations in BRAF and c-KIT were identified in 3/35 (9%) and 2/6 patients (33%), respectively. Surgery was performed in 71.4% of patients, and most received systemic treatment (65.7%). Lower disease stage, thinner Breslow depth, and surgical resection were associated with improved overall survival. Notably, age, sex, radiotherapy, and BRAF mutant status did not affect survival. Standard management typically involves immunotherapy. Cases with BRAF or c-KIT mutations may be considered for targeted therapies. Unfortunately, MM prognosis remains unfavorable, with a less than 50% survival rate at 2 years.

Anorectal Melanoma: A Case Report

Anorectal mucosal melanoma (AMM) is an infrequent and highly aggressive form of mucosal melanoma. Its rarity makes it challenging to clinically diagnose, and its initial symptoms are typically nonspecific such as rectal/anal bleeding (the most common symptom), anal pain, or the presence of an anal mass. The prognosis for this condition is generally poor, and its incidence appears to be increasing each year. AMMs often go undetected and/or are already metastasized at the time of diagnosis. We present a case report of a patient who initially presented with nonspecific symptoms of anemia and blood per rectum, and was later found to have stage IV melanoma of the anorectal region. There is a notable scarcity of literature on this disease, resulting in a lack of a comprehensive understanding of its nature. Most available information consists of isolated case reports rather than comprehensive studies. Although surgical resection remains the primary treatment approach, the majority of patients (over 80%) will die due to distant metastasis within five years after undergoing surgery. The five-year survival rate for anorectal melanoma is estimated to be between 6% and 22%.

Management of primary anorectal mucosal melanoma during the COVID-19 pandemic

Anorectal melanoma is a rare and difficult-to-diagnose highly malignant cancer with a poor prognosis. The treatment usually involves surgery and often includes adjuvants such as radiation therapy and immunotherapy. We present a case of a 77-year-old Peruvian who was eventually diagnosed with this cancer during the COVID-19 pandemic, which complicated her treatment and allowed the cancer to spread. Her treatment included abdominoperineal resection, bilateral pelvic lymphadenectomy, left internal iliac vein raffia and end colostomy, followed by 3D radiation therapy (50 Gy, 25 sessions) and systemic treatment with nivolumab, all of which were well tolerated. The patient was alive as of 20 August 2023, having survived for more than 3 years since the onset of symptoms.

Dermokine mutations contribute to epithelial-mesenchymal transition and advanced melanoma through ERK/MAPK pathways

To discover vulnerabilities associated with dermokine (DMKN) as a new trigger of the epithelial-mesenchymal transition (EMT) -driven melanoma, we undertook a genome-wide genetic screening using transgenic. Here, we showed that DMKN expression could be constitutively increased in human malignant melanoma (MM) and that this correlates with poor overall survival in melanoma patients, especially in BRAF-mutated MM samples. Furthermore, in vitro, knockdown of DMKN inhibited the cell proliferation, migration, invasion, and apoptosis of MM cancer cells by the activation of ERK/MAPK signaling pathways and regulator of STAT3 in downstream molecular. By interrogating the in vitro melanoma dataset and characterization of advanced melanoma samples, we found that DMKN downregulated the EMT-like transcriptional program by disrupting EMT cortical actin, increasing the expression of epithelial markers, and decreasing the expression of mesenchymal markers. In addition, whole exome sequencing was presented with p.E69D and p.V91A DMKN mutations as a novel somatic loss of function mutations in those patients. Moreover, our purposeful proof-of-principle modeled the interaction of ERK with p.E69D and p.V91A DMKN mutations in the ERK-MAPK kinas signaling that may be naturally associated with triggering the EMT during melanomagenesis. Altogether, these findings provide preclinical evidence for the role of DMKN in shaping the EMT-like melanoma phenotype and introduced DMKN as a new exceptional responder for personalized MM therapy.

The Role of Hedgehog Signaling in the Melanoma Tumor Bone Microenvironment

A crucial regulator in melanoma progression and treatment resistance is tumor microenvironments, and Hedgehog (Hh) signals activated in a tumor bone microenvironment are a potential new therapeutic target. The mechanism of bone destruction by melanomas involving Hh/Gli signaling in such a tumor microenvironment is unknown. Here, we analyzed surgically resected oral malignant melanoma specimens and observed that Sonic Hedgehog, Gli1, and Gli2 were highly expressed in tumor cells, vasculatures, and osteoclasts. We established a tumor bone destruction mouse model by inoculating B16 cells into the bone marrow space of the right tibial metaphysis of 5-week-old female C57BL mice. An intraperitoneal administration of GANT61 (40 mg/kg), a small-molecule inhibitor of Gli1 and Gli2, resulted in significant inhibition of cortical bone destruction, TRAP-positive osteoclasts within the cortical bone, and endomucin-positive tumor vessels. The gene set enrichment analysis suggested that genes involved in apoptosis, angiogenesis, and the PD-L1 expression pathway in cancer were significantly altered by the GANT61 treatment. A flow cytometry analysis revealed that PD-L1 expression was significantly decreased in cells in which late apoptosis was induced by the GANT61 treatment. These results suggest that molecular targeting of Gli1 and Gli2 may release immunosuppression of the tumor bone microenvironment through normalization of abnormal angiogenesis and bone remodeling in advanced melanoma with jaw bone invasion.

Genital lichen sclerosus and melanoma; a systematic review

Background

Lichen sclerosus (LSc) is a chronic, inflammatory, destructive skin disease with a predilection for the genitalia (GLSc). An association with vulval (Vu) and penile (Pe) squamous carcinoma (SCC) is now well established but melanoma (MM) has only rarely been reported complicating GLSc.

Methods

We have performed a systematic literature review of GLSc in patients with genital melanoma (GMM). Only articles that mentioned both GMM and LSc affecting either the penis or vulva were included.

Results

Twelve studies with a total of 20 patients were included. Our review shows that an association of GLSc with GMM has been more frequently reported in women and female children than men viz, 17 cases compared with three. It is notable that five of the cases (27.8%) concerned female children aged under twelve.

Discussion

These data suggest a rare association between GLSc and GMM. If proven, there arise intriguing questions about pathogenesis and consequences for counselling of patients and follow-up.

Progressing Vulvar Melanoma Caused by Instability in cKIT Juxtamembrane Domain: A Case Report and Review of Literature

In order to identify the molecular pathways governing melanoma and track its progression, the next-generation sequencing (NGS) approach and targeted sequencing of cancer genes were employed. The primary tumor, as well as metastatic tissue, of an 84-year-old patient diagnosed with vulvar melanoma (VM), were investigated. The primary tumor specimen showed multiple somatic mutations in TP53 gene, suggesting its major contribution to melanoma origin. The metastatic sample showed additional alterations, including other melanoma-related genes. Clinical relevancy is postulated to juxtamembrane region instability of KIT gene (c-KIT). We did not identify BRAF or NRAS alterations, which are typical for the most common melanoma pathway–MAPK cascade. However, it should be noted that this is the first report evidencing PDGFRA in melanoma, although its role in triggering VM needs to be further elucidated.