Rare but Still There: An Interesting Case of Cytokeratin 20-Negative Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) of the skin is a rare and aggressive primary neuroendocrine tumor that mainly involves sun-exposed areas and can metastasize to other parts of the body. Due to varied clinical features and the sharing of similar histological features with other neuroendocrine tumors, diagnosis can be challenging. Therefore, immunohistochemistry plays an important role in diagnosis, and the characteristic perinuclear staining with cytokeratin 20 (CK 20) helps to differentiate it from other morphologically similar tumors, especially metastatic small cell carcinoma of the lung. We describe an interesting case of a 78-year-old female who was referred by a general practitioner (GP) with a few months' history of asymptomatic, rapidly enlarging, erythematous, nodular lesion on her left upper arm. Due to clinical findings and the location of the lesion on the sun-exposed area, wide differential diagnoses were considered. The lesion was excised for histological diagnosis. Surprisingly, morphological features favour the diagnosis of a neuroendocrine tumor. However, histological features including immunohistochemistry rendered it difficult to differentiate between primary cutaneous neuroendocrine carcinoma (Merkel cell CA) and metastatic small cell carcinoma of the lung due to the lack of specific and sensitive marker of CK 20 on immunohistochemistry. Subsequently, the patient had computer tomography of the chest/abdomen and pelvis (CTTAP) and positron emission tomography (PET) scans to rule out underlying primary malignancy. The case was also discussed at local and specialist skin multidisciplinary team meetings (MDT) including neuroendocrine MDT and a consensus diagnosis of Merkel cell carcinoma of the skin with negative CK 20 was established.

Hiding in Plain Sight: An Atypical Presentation of the Uncommon Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a cutaneous neoplasm that is challenging to diagnose secondary to its rarity. We report a case involving a 76-year-old Caucasian female with a seemingly benign skin nodule on her right forearm. Histopathological analysis revealed characteristics of MCC, including uniform round cells with minimal cytoplasm and fine granular chromatin. Immunohistochemical staining confirmed insulinoma-associated protein 1 (INSM1) positivity, a marker with high sensitivity and specificity in localized MCC diagnosis. The subsequent treatment plan involved wide local excision, sentinel lymph node evaluation, and radiation therapy, aligning with therapeutic standards for MCC. Negative positron emission tomography (PET) scans and follow-up for one year have demonstrated no evidence of recurrence or additional lesions. This case demonstrates the challenges in diagnosing MCC and the need for histopathological and immunohistochemical assessments for an accurate diagnosis. Diagnostic markers, INSM1, are important distinguishing factors between MCC and other skin cancers. In conclusion, our case contributes to the literature in diagnosing MCC and successful treatment, while emphasizing the need for immunohistochemical markers for accurate diagnosis and guiding therapeutic decisions.

Nationwide Case-Control Analysis of Merkel Cell Carcinoma and Associated Skin Cancer Comorbidities: An Examination of the All of Us Database

Introduction Merkel cell carcinoma is an aggressive neuroendocrine tumor that is related to immunosuppression and the Merkel cell polyomavirus. It is more common on the head and neck and has been associated with other skin malignancies such as basal cell carcinoma, squamous cell carcinoma, and melanoma. However, there has never been a nationwide investigation that quantifies Merkel cell carcinoma's connection with these subgroups. Methods Utilizing the National Institutes of Health's All of Us open-access database, a retrospective study was conducted by filtering for Merkel cell carcinoma through the International Classification of Diseases, 9th and 10th Clinical Modification codes 209.* and C4A.*, respectively. This led to the inclusion of 41 patients in the study, with each instance compared to four control patients without merkel cell carcinoma, matched by age, race, and gender. The data's demographics and skin cancer co-morbidities were collected and evaluated with odds ratios and 95% confidence intervals using Wald's method. Results In patients with merkel cell carcinoma, a statistically significant gradient of increasing risk for developing basal cell carcinoma (Odds Ratio, 11.63; 95% Confidence Interval, 4.30-31.45; P < 0.0001), squamous cell carcinoma (Odds Ratio, 15.09; 95% Confidence Interval, 3.87-58.84; P = 0.0001), and melanoma (Odds Ratio, 27.94; 95% Confidence Interval, 3.26-239.48; P = 0.0024) was observed. The race/ethnicity demographics showed that 85.4% of the patients were white, and they were at the highest risk of developing merkel cell carcinoma. However, the study has limitations, such as the inability to identify the stage of merkel cell carcinoma among patients and the lack of consideration for other confounding variables. Conclusion The study examines the link between merkel cell carcinoma and other skin malignancies, underscoring the need for more national research to better understand the underlying causes that contribute to this link. The findings also indicate the possibility of sample bias in the All of Us database, emphasizing the need to assess the patient population's representativeness in such investigations.

Programmed Death-1 Inhibitor Immunotherapy-Induced Symptomatic Toxic Thyroid Nodule

Immune checkpoint inhibitors, specifically programmed death-ligand 1 (PD-LI) inhibitors, are immune modifying medications that increasingly treat specific types of cancer. They are known to cause many side effects, including thyroid-related side effects. The use of PD-L1 inhibitors can cause hypothyroidism most commonly, while hyperthyroidism occurs less frequently. This case report describes a patient who developed a toxic thyroid nodule while taking the PD-L1 inhibitor, avelumab, for the treatment of Merkel cell carcinoma. It highlights the need for more research into the specific mechanisms by which these therapies can cause hyperthyroidism. It also raises the question regarding the association between the use of these medications and the development or worsening of thyroid nodules.

Dissecting the tumour immune microenvironment in merkel cell carcinoma based on a machine learning framework

Merkel cell carcinoma (MCC) is a primary cutaneous neoplasm of neuroendocrine carcinoma of the skin, which is characterized by molecular heterogeneity with diverse tumour microenvironment (TME). However, we are still lack knowledge of the cellular states and ecosystems in MCC. Here, we systematically identified and characterized the landscape of cellular states and ecotypes in MCC based on a machine learning framework. We obtained 30 distinct cellular states from 9 immune cell types and investigated the B cell, CD8 T cell, fibroblast, and monocytes/macrophage cellular states in detail. The functional profiling of cellular states were investigated and found the genes highly expressed in cellular states were significantly enriched in immune- and cancer hallmark-related pathways. In addition, four ecotypes were further identified which were with different patient compositions. Transcriptional regulation analysis revealed the critical transcription factors (i.e. E2F1, E2F3 and E2F7), which play important roles in regulating the TME of MCC. In summary, the findings of this study may provide rich knowledge to understand the intrinsic subtypes of MCCs and the pathways involved in distinct subtype oncogenesis, and will further advance the knowledge in developing a specific therapeutic strategy for these MCC subtypes.

Successful Treatment of Facial Merkel Cell Carcinoma Using CyberKnife Radiotherapy Alone: A Case Report

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin tumor. Herein, we present a case of MCC which was successfully treated with radiotherapy alone using CyberKnife® (CK) (Accuray Incorporated, Sunnyvale, California, United States). An 86-year-old female patient presented with multiple painless pink rash skin tumors on the left cheek. The patient was diagnosed with MCC based on a lesion biopsy (T2cN2M0, stage IIIB). The patient was referred for CK radiotherapy (CKR) at our institution because of her advanced age and inoperative lesions. The patient underwent CKR alone, with a planning target volume (PTV) of 14.9 ml, a prescribed dose of 30 Gy, a maximum dose of 46.2 Gy, and an isodose line (the minimum dose of 95% of the PTV) of 65% in 10 fractions for 13 days. The lesions had completely regressed on the last day of CKR. Left cervical lymph node metastasis (CLNM) appeared 10 months after CKR. The patient underwent a second CKR for CLNM, the PTV was 4.6 ml, and the prescribed dose was 27 Gy in three fractions for three days. The CLNM had completely regressed one month later after the second CKR. Primary lesions did not recur for 33 months after the initial CKR, and CLNM did not reappear for 23 months after the second CKR with good cosmetic results. No CKR-related adverse event occurred in our follow-up period. Our present case indicates that CKR is an effective treatment option for patients with MCC, particularly elderly patients who may not be suitable candidates for extensive surgical resection.

The Evaluation and Treatment of Merkel Cell Carcinoma and Brain Metastasis: A Case Report and Review of the Literature

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor associated with high mortality if metastases are identified. Currently, there is no standardized nor curative treatment for neurometastatic MCC. In this study, we have reviewed the more recent cases and the use of immunotherapy in a population. In this case report and review, we present a case of MCC with brain metastasis currently undergoing treatment with immunotherapy (pembrolizumab) resulting in an initial complete response with a progression-free survival time of five months. We also review the past reported literature and the 11 newly presented cases on their clinical presentation of neurometastatic MCC, immunohistochemical markers, and treatment outcomes. In summary, immunotherapy initially showed a promising response with the complete elimination of MCC brain metastasis. The early aggressive treatment of pembrolizumab with stereotactic radiosurgery should be considered as this treatment plan has shown improved therapeutic effects compared to the standard chemoradiation therapy. Further investigations are needed to determine the efficacy and response of immunotherapy use for neurometastatic MCC.

Implications of intrinsic disorder and functional proteomics in the merkel cell polyomavirus life cycle

Infection with merkel cell polyomavirus (MCPyV) is implicated in the development of merkel cell carcinoma (MCC), a rare but aggressive skin cancer. MCC has a mortality rate near 50%, and incidence has been rapidly increasing in recent decades, making development of improved treatment strategies critical to addressing its growing social burden. The parallel increasing necessity for novel research to better understand MCPyV pathogenesis has prompted numerous studies in recent years, yet the role of intrinsic disorder in MCPyV proteins remains unexplored. This study carries out computational characterization of intrinsic disorder within the MCPyV proteome and suggests mechanisms that may contribute to the oncogenicity of the virus to invade and hijack host immune systems. Our analysis finds that significant levels of intrinsic disorder are present in proteins LT, ALTO, 57kT, and VP1, and suggests that regions of sT may also contain large, disordered regions. The investigation further shows correlation of disorder propensity with the outputs for functional predictors of eukaryotic linear motifs (ELMs), molecular recognition features (MoRFs), and propensity for liquid-liquid phase separation (LLPS). Our findings indicate that MCPyV may use disorder and phase condensation to alter viral function that may accentuate or provide the basis for oncogenic activities. It is intended that this study will inform future experimental validation efforts around the phase separation capacity of MCPyV and its host protein-protein interactions. Furthermore, we hope to inform other investigators on the potential role of disorder in the MCPyV life cycle toward ultimately progressing the development of novel therapeutic agents.

Case Report: Stereotactic body radiation treatment for immunotherapy escaped oligometastatic progression in cutaneous melanoma and merkel cell carcinoma

Oligometastatic progression represents a unique manifestation of tumor immune-escape that can lead to disease progression during treatment with immune checkpoint inhibitor (ICI). The diagnosis and further optimal management of oligometastatic progression through ICI remains unclear. Diagnostic challenges include practical limitations due to the anatomical sites of oligometastatic progression, such as the para-aortic region, where traditional tissue biopsy carries high risk, and circulating-tumor DNA (ctDNA) could aid in diagnosis and disease monitoring as a supplement to surveillance imaging. In this report, we describe two cases of one patient with metastatic melanoma and the other with metastatic Merkel cell carcinoma (MCC) who were treated with ICI and later developed localized resistance due to oligometastatic progression. We further highlight our experience using stereotactic body radiation therapy (SBRT) as a salvage approach to treat the oligometastatic progression. In addition, we describe the temporal and dynamic relationship of circulating-tumor DNA (ctDNA) prior to, during and after SBRT, which highly suggested the diagnosis without obtaining a histological specimen. Our cases highlight a potential role for SBRT in the management of oligometastatic progression. However, large prospective trials are essential to confirm the utility of this approach.

Catastrophic Merkel Cell Carcinoma in a Liver Transplant Recipient

Merkel cell carcinoma (MCC) is a rare skin cancer, is difficult to diagnose, and carries a high mortality rate. Solid organ transplant recipients (SOTR) are at a disproportionately increased risk of MCC and other malignancies due to chronic immunosuppression. We discuss the case of a 47-year-old woman with a remote history of liver transplant on chronic immunosuppression with tacrolimus for over a decade who presented for a third recurrence of MCC on her left forearm. This case report underscores the importance of a risk-stratified approach to regular dermatologic care and skin cancer screening in this vulnerable population.

Large Intestinal Obstruction and Perforation From Metastatic Merkel Cell Carcinoma: A Case Report

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine neoplasm of the skin that has a high propensity to metastasize. Abdominal metastases of MCC have been described previously though these are typically regional with nodal spread. We report the case of a 60-year-old man with a history of left upper extremity MCC who had resection, radiation therapy, and immunotherapy. He ultimately developed large bowel obstruction from metastatic intraperitoneal implants. A 6 cm mass at the descending colon was biopsied and proven to be metastatic MCC. The tumor eroded through the wall of the colon and perforated, requiring emergent colectomy for septic shock. Herein, we describe the first case of colonic perforation secondary to metastatic MCC. This case illustrates the importance of expedient and multifactorial management of patients with rapidly growing metastatic colonic tumors that are at risk for perforation.

Merkel Cell Carcinoma of the Left Cheek With Testicular Metastasis: An Uncommon Occurrence

Merkel cell carcinoma (MCC) is an infrequent and aggressive neuroendocrine tumor of the skin. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is an effective imaging technique with good diagnostic accuracy that may be used to help stage MCC and for detecting unexpected recurrences and distant metastatic disease. Other causes of testicular neoplasms, such as primary testicular tumors, lymphomas, or anaplastic small cell melanomas, are difficult to differentiate from MCC testicular metastases on imaging, and tumor markers and histopathology will help confirm it. The current case is a 65-year-old non-immunocompromised male with Merkel cell carcinoma who was incidentally identified with testicular metastases on PET/CT and confirmed on histopathology.

Correlation of Ultraviolet Radiation Levels With the Incidence of Cutaneous Squamous Cell and Merkel Cell Carcinomas in Non-sunbelt Locales in the United States: 2010-2017

BACKGROUND

Non-melanoma skin cancer (NMSC) is the most common human malignancy worldwide, with increasing incidence in the United States (US). Recent environmental data have shown that ultraviolet radiation (UVR) levels have increased in the US, particularly in the higher latitudes, but the potential impact of this on NMSC incidence is not well known, despite estimates that 90% of NMSC is due to sun exposure. Our exploratory study synthesizes environmental data with demographic and clinical data to determine whether UV indices (UVIs) and non-sunbelt (non-SB) locale (latitudes >40 degrees, which comprises most of the US) might contribute to incidence rates of two types of NMSC: cutaneous squamous cell and Merkel cell carcinomas.

METHODS

UVIs from 2010 to 2017 were obtained from the National Oceanic and Atmospheric Administration database and meshed with corresponding locales in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database (version 8.4.0.1). Four SB and five NSB locales contained sufficient data for analysis. Linear mixed modeling was performed with the outcome variable of the age-adjusted incidence of NMSC cancer (comprised of cutaneous squamous cell carcinoma of the head and neck (CSCCHN) and Merkel cell carcinoma (MCC)), the two most common types of NMSC contained within SEER). Non-SB locale and percent of days with UVI >3 were independent variables.

RESULTS

Percent of days with UVI >3 increased during this period, as did the overall NMSC (combined CSCCHN and MCC) skin cancer incidence, though MCC incidence alone did not increase during our study period. Environmental factors that significantly contributed to the age-adjusted overall NMSC (combined CSCCHN and MCC) cancer incidence (per 100,000 individuals) included NSB locale (b=1.227, p=0.0019) and percent of days with UVIs >3 (b=0.028, p<0.0001), as well as clinical factors of percent white race and percent male, by linear mixed modeling.

CONCLUSIONS

Our results are limited by the completeness of the NOAA and SEER databases, and do not include basal cell carcinoma. Nevertheless, our data demonstrate that environmental factors, such as latitude in NSB locale and UVI indices, can affect the age-adjusted overall NMSC (defined as CSCCHN and MCC in this study) incidence even in this relatively short period of time. Prospective studies over longer time periods are needed to identify the extent to which these findings are clinically significant so that increased educational efforts to promote sun-safe behaviors can be maximally effective.

Increased Vertebral Gallium-68-DOTATATE Activity on Positron Emission Tomography-Computed Tomography in Merkel Cell Carcinoma: Not Always Metastasis

Merkel cell carcinoma (MCC) is a rare neuroendocrine dermal malignancy seen in elderly light-skinned individuals, associated with immunosuppression and Merkel cell polyomavirus infection. As a neuroendocrine tumor, the recurrence and metastasis of MCC can be evaluated using positron emission tomography-computed tomography (PET-CT) with the Gallium-68-DOTATATE (Ga-68-DOTATATE) radiotracer, which has demonstrated increased sensitivity to neuroendocrine metastases when compared to F-18 fluorodeoxyglucose (FDG). Here, we present the case of a patient with known metastatic MCC with a new, abnormal focus of increased radiotracer activity in the thoracic spine on Ga-68-DOTATATE PET-CT suspected to represent a metastatic lesion. Further evaluation with MRI revealed a benign vertebral hemangioma, highlighting the limitations of this radiotracer in the setting of benign spinal lesions. Multimodality imaging findings of metastatic MCC and potential pitfalls of Ga-68-DOTATATE PET-CT staging are discussed.

Detection of Sentinel Lymph Nodes Using Indocyanine Green After Failing Scintigraphy in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare but highly aggressive skin cancer that carries a high rate of lymph node involvement and death. The National Comprehensive Cancer Network recommends sentinel lymph node (SLN) biopsy for the staging of the disease. Scintigraphy using radioactive isotopes (RI) such as technetium 99m (Tc99) remains the gold standard for the detection of SLNs, however, recently indocyanine green (ICG) fluorescence imaging has been used to aid in the detection of SLNs.We present the case of a patient who presented with MCC of the face and two SLNs successfully identified with ICG fluorescence despite the fact that they were not detected by intraoperative scintigraphy using Tc99. The use of ICG fluorescence imaging in MCC is safe and improves the ability to detect SLNs when combined with RI.

A review on the oncogenesis of Merkel cell carcinoma: Several subsets arise from different stages of differentiation of stem cell

Merkel cell carcinoma (MCC), a rare primary cutaneous neuroendocrine neoplasm, is extremely aggressive and has a higher mortality rate than melanoma. Based on Merkel cell polyomavirus (MCPyV) status and morphology, MCCs are often divided into several distinct subsets: pure MCPyV-positive, pure MCPyV-negative, and combined MCC. MCPyV-positive MCC develops by the clonal integration of viral DNA, whereas MCPyV-negative MCC is induced by frequent ultraviolet (UV)-mediated mutations, that are characterized by a high mutational burden, UV signature mutations, and many mutations in TP53 and retinoblastoma suppressor gene (RB1). Combined MCC consists of an intimate mix of MCC and other cutaneous tumor populations, and is usually MCPyV-negative, with rare exceptions. Based on the existing subsets of MCC, it is speculated that there are at least 4 stages in the natural history of stem cell differentiation: primitive pluripotent stem cells, divergent differentiated stem cells, unidirectional stem cells, and Merkel cells (or epidermal/adnexal cells). In the first stage, MCPyV may integrate into the genome of primitive pluripotent stem cells, driving oncogenesis in pure MCPyV-positive MCC. If MCPyV integration does not occur, the stem cells enter the second stage and acquire the ability to undergo multidirectional neuroendocrine and epidermal (or adnexal) differentiation. At this stage, accumulated UV-mediated mutations may drive the development of combined MCC. In the third stage, the stem cells differentiate into unidirectional neuroendocrine stem cells, UV-mediated mutations can induce carcinogenesis in pure MCPyV-negative MCC. Therefore, it has been speculated that several subsets of MCCs arise from different stages of differentiation of common stem cells.

The Antineoplastic Effect of Dimethyl Fumarate on Virus-Negative Merkel Cell Carcinoma Cell Lines: Preliminary Results

Merkel cell carcinoma (MCC) is a rare, difficult-to-treat skin cancer once immunotherapy has failed. MCC is associated either with the clonal integration of the Merkel cell polyomavirus (MCPyV) or mutagenic UV-radiation. Fumaric acid esters, including dimethyl fumarate (DMF), have been shown to inhibit cell growth in cutaneous melanoma and lymphoma. We aimed to explore the effects of DMF on MCPyV-negative MCC cell lines. Three MCC cell lines (MCC13, MCC14.2, and MCC26) were treated with different doses of DMF. The cytotoxic effects and cell proliferation were assessed by the MTT cytotoxicity assay and BrdU proliferation assay at different time points. A significant reduction in cell viability and proliferation were demonstrated for all the cell lines used, with DMF proving to be effective.

Racial and Ethnic Healthcare Disparities in Skin Cancer in the United States: A Review of Existing Inequities, Contributing Factors, and Potential Solutions

Objective

Racial and ethnic health disparities affect the diagnosis and management of melanoma and nonmelanoma skin cancers, leading to deleterious outcomes. Non-Hispanic White patients make up the majority of skin cancers cases, yet racial and ethnic minorities have poorer prognoses and outcomes. The skin cancer literature is fragmented with regards to potential contributors to these healthcare disparities. In this article, we provide a comprehensive review of the skin cancer literature to briefly quantify racial and ethnic inequities, highlight contributing factors, and propose practical changes that can be made.

Methods

A PubMed search was completed to identify articles related to racial and ethnic health care disparities in the context of melanoma, basal cell carcinoma, squamous cell carcinoma, Merkel cell carcinoma, and dermatofibrosarcoma protuberans.

Results

Relative to non-Hispanic White patients, patients of racial and ethnic minorities have differing clinical presentations of skin cancers and genetic risk factors. Insurance, access to specialty care, cultural beliefs, and available educational resources further contribute to racial and ethnic disparities.

Limitations

We are limited to the level of detail provided in the existing literature, and at some times are unable to distinguish race of Hispanic populations. We also acknowledge that there are different nationalities grouped under these broad labels as well as multi-racial populations that may not be accounted for.

Conclusion

Awareness of and familiarization with innate factors and potentially more modifiable contributors can help inform efforts to close the observed gap in racial and ethnic inequities.

Prevalence of Merkel Cell Polyomavirus in Normal and Lesional Skin: A Systematic Review and Meta-Analysis

The prevalence of Merkel cell polyomavirus(MCPyV) in Merkel cell carcinoma(MCC) and non-MCC skin lesions and its possible role in the etiology of other skin diseases remain controversial. To systematically assess the association between MCPyV infection and MCC, non-MCC skin lesions, and normal skin. For this systematic review and meta-analysis, a comprehensive search for eligible studies was conducted using Medline Ovid, Pubmed, Web of Science, and the Cochrane CENTRAL databases until August 2021; references were searched to identify additional studies. Observational studies that investigated the association between MCPyV infection and MCC, non-MCC skin lesions, and normal skin using polymerase chain reaction(PCR) as a detection method and provided sufficient data to calculate the prevalence of MCPyV positivity. A total of 50 articles were included in the study after exclusion criteria were applied. Two reviewers independently reviewed and assessed the eligibility of the studies, and all disagreements were resolved by consensus. To determine the association between MCPyV and MCC, overall odds ratio (OR) were calculated with 95% CI using a random-effects model. Single-arm meta-analyses were performed to examine the prevalence rate of MCPyV+ in MCC, non-MCC skin lesions, and normal skin. The primary analysis was the prevalence rate of MCPyV+ in MCC. Secondary outcomes included the prevalence rate of MCPyV+ in non-MCC skin lesions and normal skin. A total of 50 studies involving 5428 patients were reviewed based on our inclusion and exclusion criteria. Compared with the control group, MCPyV infection was significantly associated with MCC (OR = 3.51, 95% CI = 2.96 - 4.05). The global prevalence of MCPyV+ in MCC, melanoma, squamous cell carcinoma, basal cell carcinoma, Bowen's disease, actinic keratosis, keratoacanthoma, seborrheic keratosis, and normal skin was 80%, 4%, 15%, 15%, 21%, 6%, 20%, 10%, and 11%, respectively. The current results suggest that MCPyV infection is significantly associated with an increased risk of MCC. However, the low prevalence rate of MCPyV+ in non-MCC skin lesions does not exclude a pathogenic association of this virus with the development of non-MCC skin lesions.

Genomic evidence suggests that cutaneous neuroendocrine carcinomas can arise from squamous dysplastic precursors

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma without a known dysplastic precursor. In some cases, MCC is associated with SCCIS in the overlying epidermis; however, the MCC and SCCIS populations display strikingly different morphologies, and thus far a relationship between these components has not been demonstrated. To better understand the relationship between these distinct tumor cell populations, we evaluated 7 pairs of MCC-SCCIS for overlapping genomic alterations by cancer profiling panel. A subset was further characterized by transcriptional profiling and immunohistochemistry. In 6 of 7 MCC-SCCIS pairs there was highly significant mutational overlap including shared TP53 and/or RB1 mutations. In some cases, oncogenic events previously implicated in MCC (MYCL gain, MDM4 gain, HRAS mutation) were detected in both components. Although FBXW7 mutations were enriched in MCC, no gene mutation was unique to the MCC component across all cases. Transcriptome analysis identified 2736 differentially expressed genes between MCC and SCCIS. Genes upregulated in the MCC component included Polycomb repressive complex targets; downregulated transcripts included epidermal markers, and immune genes such as HLA-A. Immunohistochemical studies revealed increased expression of SOX2 in the MCC component, with diminished H3K27Me3, Rb, and HLA-A expression. In summary, MCC-SCCIS pairs demonstrate clonal relatedness. The shift to neuroendocrine phenotype is associated with loss of Rb protein expression, decrease in global H3K27Me3, and increased expression of Merkel cell genes such as SOX2. Our findings suggest an epidermal origin of MCC in this setting, and to our knowledge provide the first molecular evidence that intraepithelial squamous dysplasia may represent a direct precursor for small cell carcinoma.

Conditional survival estimates for merkel cell carcinoma reveal the dynamic nature of prognostication

BACKGROUND AND OBJECTIVES

Conditional survival (CS) analysis has emerged as a dynamic prognostication methodology. The goal of this study was to determine disease-specific CS rates in Merkel cell carcinoma (MCC).

METHODS

This retrospective study included patients with MCC from the Surveillance Epidemiology and End Results (SEER) registry (1988-2016). Stage-specific 5-year MCC-specific CS rates for study and survivor cohorts were estimated, and the significance of clinicopathologic factors to predict 1-year MCC-specific death was evaluated using multivariate logistic regression.

RESULTS

Within stage, 5-year CS survival rates improved with increasing survivorship. Pathologic Stage I patients had the highest 5-year CS rate at diagnosis (89.1%) but the smallest increase over time (96% among 5-year survivors). Stage IV patients experienced the greatest change in 5-year CS rates from 25.4% (at diagnosis) to 88% (5-year survivors). At diagnosis stage, age, sex, and primary site were all significantly associated with 1-year MCC-related death in the multivariate analysis. In contrast, among 5-year survivors only sex and age at diagnosis were significant predictors.

CONCLUSIONS

MCC CS rates improved across all disease stages over time. Additionally, the relationships of prognostic factors with 1-year MCC-death changed with increasing survivorship. This perspective can provide a foundation for informed decision-making.

Circulating microRNA biomarkers in melanoma and non-melanoma skin cancer

INTRODUCTION

Skin cancer is the most common type of cancer and is classified in melanoma and non-melanoma cancers, which include basal cell, squamous cell and Merkel cell carcinoma. Specific microRNAs are dysregulated in each skin cancer type. MicroRNAs act as oncogene or tumor suppressor gene regulators and are actively released from tumor cells in the circulation. Cell-free microRNAs serve many, and possibly yet unexplored, functional roles, but their presence and abundance in the blood has been investigated as disease biomarker. Indeed, specific microRNAs can be isolated and quantified in the blood, usually in serum or plasma fractions, where they are uncommonly stable. MicroRNA levels reflect underlying conditions and have been associated with skin cancer presence, stage, evolution, or therapy efficacy.

AREAS COVERED

In this review, we summarize the state of the art on circulating microRNAs detectable in skin cancer patients including all the studies that performed microRNA identification and quantification in the circulation using appropriate sample size and statistics and providing detailed methodology, with a specific focus on diagnostic and prognostic biomarkers.

EXPERT OPINION

Circulating microRNAs display a relevant biomarker potential. We expect the development of methodological guidelines and standardized protocols for circulating miRNA quantification in clinical settings.

Viral Status Predicts the Patterns of Genome Methylation and Decitabine Response in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma that is classified as Merkel cell polyomavirus-positive (virus positive [VP]) or Merkel cell polyomavirus-negative (virus negative [VN]). Epigenetic changes, such as DNA methylation, can alter gene expression and influence cancer progression. However, patterns of DNA methylation and the therapeutic efficacy of hypomethylating agents have not been fully explored in MCC. We characterized genome-wide DNA methylation in 16 MCC cell lines from both molecular subclasses in comparison with other cancer types and found that the overall profile of MCC is similar to that of small-cell lung carcinoma. Comparison of VP MCC with VN MCC revealed 2,260 differentially methylated positions. The hypomethylating agent decitabine upregulated the expression of antigen-presenting machinery in MCC cell lines and stimulated membrane expression of HLA-A in VP and VN MCC xenograft tumors. Decitabine also induced prominent caspase- and large T antigen‒independent cell death in VP MCC, whereas VN MCC cell lines displayed decreased proliferation without increased cell death. In mouse xenografts, decitabine significantly decreased the size of VP tumors but not that of VN tumors. Our findings indicate that viral status predicts genomic methylation patterns in MCC and that decitabine may be therapeutically effective against MCC through antiproliferative effects, cell death, and increased immune recognition.

A web-based predictive model for overall survival of patients with cutaneous Merkel cell carcinoma: A population-based study

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine carcinoma with a high mortality rate, so it is necessary to create models to predict overall survival of MCC. We developed an easy-to-use web-based calculator to predict the OS of MCC patients based on the nomogram.

METHODS

MCC patients between 2004 and 2015 were collected from the Surveillance, Epidemiology, and End Results (SEER) database and randomly assigned to training and validation cohorts. Patients between 2016-2017 serve as the external validation cohort. Relevant risk factors were identified by univariate and multivariate COX hazards regression methods and combined to produce nomograms. The concordance index (C-index), area under the receiver operating characteristic (AUC) curve, and calibration plots have demonstrated the predictive power of the nomograms. Decision curve analysis (DCA) was used to measure nomograms in clinical practice. Patients were divided into three groups according to the scores of the nomogram.

RESULTS

A total of 3480 patients were randomly assigned to the training group and validation group in this study. Meaningful prognostic factors were applied to the establishment of nomograms. The C-index for OS was 0.725 (95% CI: 0.706-0.741) in the training cohort and 0.710 (95% CI: 0.683-0.737) in the validation cohort. In the external validation cohort, C-index was 0.763 (95% CI: 0.734-0.792). The C-index of training cohort, validation cohort and external validation cohort for CSS were 0.743 (95% CI:0.725-0.761), 0.739(95%CI:0.712-0.766) and 0.774 (95%CI:0.735-0.813), respectively. The AUC and calibration plots of 1-, 3-, and 5-year OS rates showed that the nomogram had good predictive power. DCA demonstrated that the nomogram constructed in this study could provide a clinical net benefit. Our calculator demonstrated excellent predictive capabilities for better risk grouping of MCC patients.

CONCLUSION

We created novel nomograms of prognostic factors for MCC, which more accurately and comprehensively predicted 1-, 3-, and 5-year OS/CSS in MCC patients. We established a calculator which can easily and quickly calculate the risk grouping of MCC patients by inputting clinically relevant characteristics. This can help clinicians identify high-risk patients as early as possible, carry out personalized treatment, follow-up, and monitoring, and improve the survival rate of MCC patients.

An Extremely Rare Case of Metastatic Merkel Carcinoma of the Liver

Merkel cell carcinoma (MCC) is a rare but highly aggressive skin cancer with neuroendocrine features. The important risk factors in the development of MCC include immunocompromised state, advanced age, and White skin complexion. The pathogenesis is associated with either the presence of Merkel cell polyomavirus or chronic exposure to ultraviolet radiation. MCC usually occurs in the sun-exposed areas of the skin and has the potential for regional and distant metastasis. Only 8% of the cases of MCC present with distant metastatic disease with liver, lungs, bone, and brain being commonly involved. Here, we report such an extremely rare case of a 78-year-old gentleman with a history of cutaneous T-cell lymphoma, who presented to the hospital with abnormally elevated liver enzymes, which on further evaluation was detected to have metastatic MCC of the liver.

Volumetric Modulated Arc Therapy Capabilities for Treating Lower-Extremity Skin Affected by Several Merkel Cell Carcinoma Nodules: When Technological Advances Effectively Achieve the Palliative Therapeutic Goal while Minimising the Risk of Potential Toxicities

The peculiar and rare clinical condition below clearly requires a customized care approach in the context of personalized medicine. An 80-year-old female patient who was subjected in 2018 to surgical removal of a cutaneous Merkel cell carcinoma (MCC) nodule located on the posterior surface of the left thigh and to three subsequent palliative radiotherapy treatments developed a fourth relapse in October 2020, with fifteen nodular metastases located in the left thigh and leg. Since the overall macroscopic disease was still exclusively regionally located and microscopic spread was likely extended also to clinically negative skin of the thigh and leg, we performed an irradiation of the whole left lower extremity. For this purpose the total target (65.5 cm) was divided into three sub-volumes. Dose prescription was 30 Gy in 15 daily fractions. A sequential boost of 10 Gy in 5 daily fractions was planned for macroscopic nodules. Plans were calculated by means of volumetric modulated arc therapy (VMAT) with the field overlap technique. Thanks to this, we obtained a homogeneous dose distribution in the field junction region; avoidance structures were delineated in the central part of the thigh and leg with the aim of achieving an optimal superficial dose painting and to reduce bone exposure to radiation. This case study demonstrates that VMAT allows for a good dose coverage for circumferential cutaneous targets while sparing deeper organs at risk. A reproducible image-guided set-up is fundamental for an accurate and safe dose delivery. However, local treatments such as radiotherapy for very advanced MCC of the lower extremities might have limited impact due to the high probability of systemic progression, as illustrated in this case. Radiation is confirmed as being effective in preventing MCC nodule progression toward skin wounding.

Merkel cell carcinoma in situ: A systematic review of prognosis and management

BACKGROUND

Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine tumour. While dermally invasive MCC is known to have a five-year survival of only 30-40%, the prognosis and management of MCC in situ (MCCis) is not widely reported.

OBJECTIVE

We present a systematic review to elucidate the prognosis and management of MCCis.

METHODS

We performed a systematic review, searching three databases to 01 June 2021. Case reports, cohort studies, clinical trials and literature reviews were considered for inclusion.

RESULTS

We identified 26 cases of MCCis published in the literature with a median age of 74 years and involving 19 males and 7 females. Most cases were on the face and neck (n = 17), followed by upper limb (n = 8) and lower limb (n = 1). Sentinel lymph node biopsy was performed in three patients, and all were negative. One subject underwent adjuvant radiotherapy. No MCCis-associated deaths were reported.

CONCLUSION

This review suggests that MCCis has an excellent prognosis with minimal, if any, risk of mortality and a very low risk of dermal invasion and recurrence when treated with wide local excision alone. Sentinel lymph node biopsy is unlikely to be useful for MCCis.

The texture of collagen in the microenvironments of Merkel cell carcinoma

ABSTRACT

Solid tumors typically contain high levels of fibrillar collagen. The increased stromal collagen deposition usually promotes cancer progression since biochemical and biophysical cues from tumor-associated collagen fibers stimulate neoplastic cells. Few studies have investigated the relationship between Merkel cell carcinoma (MCC) and the extracellular matrix (ECM), but there are no works evaluating collagen.This is an observational, analytical, retrospective study including 11 patients with MCC. Primary tumor-stained sections were evaluated by second harmonic generation microscopy and texture analysis.Peritumoral texture features (area fraction, mean gray value, entropy, and contrast) showed much lower values than normal skin (P < .0001) revealing extensively altered structure of peritumoral collagen fibers. These differences were not significant between tumors with unfavorable and favorable known prognostic factors.Profound changes in collagen fibers present in the stroma accompanying primary MCC may contribute to the aggressive behavior of this tumor. Our results indicate that whatever MCC histological subtype, size or anatomical location, MCC promotes the same type of ECM for its development. As an outlook, therapies using ECM macromolecules or fibroblasts (the architects of ECM remodeling) as target could be useful in the treatment of MCC.

Merkel Cell Carcinoma: An Immunotherapy Fairy-Tale?

Merkel cell carcinoma (MCC) is a rare, highly aggressive, neuroendocrine cutaneous tumor. The incidence of MCC is growing worldwide, and the disease-related mortality is about three-fold higher than melanoma. Since a few years ago, very little has been known about this disease, and chemotherapy has been the standard of care. Nowadays, new discoveries about the pathophysiology of this neoplasm and the introduction of immunotherapy allowed to completely rewrite the history of these patients. In this review, we provide a summary of the most important changes in the management of Merkel cell carcinoma, with a focus on immunotherapy and a landscape of future treatment strategies.

The Association of Radiation Therapy and Chemotherapy on Overall Survival in Merkel Cell Carcinoma: A Population-Based Analysis

Purpose/objective(s) Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous neoplasm traditionally managed with surgical resection followed by radiotherapy (RT). With the recent approval of checkpoint inhibitors, chemotherapy is less commonly utilized. We analyzed the impact of RT and chemotherapy on overall survival (OS) in patients with MCC using Surveillance, Epidemiology, and End Results (SEER), a population-level database. Materials and methods We performed retrospective analyses on SEER 18 Custom Data registries for MCC (ICD-0-3 8247). Data from 1980 to 2016 was queried for analysis, and an initial list of 9,792 patients was populated (ICD: C00, C07.9, C44, C80.9). Selection for cases with chemotherapy and RT status, single primary tumor, primary tumor location and surgery treatment type yielded 5,002 cases for analysis. Baseline characteristics were compared with Chi-square or Mann-Whitney U test. Univariate and multivariable analysis using Kaplan-Meier and Cox proportional hazards regression modeling were performed. Propensity-score matched analysis with inverse probability of treatment weighting (IPTW) was used to account for indication bias. Results Median follow-up time was 178 months (68 to 217 months). Independent prognostic factors positively correlated with increased OS, for both unadjusted Multivariate analysis and IPTW adjusted MVA were age, male sex, year of diagnosis, stage, RT status, and chemotherapy status. On adjusted MVA, use of chemotherapy was associated with worse OS (hazard ratio: 1.22 [95% CI 1.1-1.35], p<0.001), whereas RT was associated with improved OS (HR:0.9 [95% CI, 0.83-0.97], p=0.008). Conclusions The current study demonstrates that RT is associated with improved survival for patients with MCC. Chemotherapy was associated with worse OS. This supports the recent clinical shift towards immune checkpoints inhibitors as standard of care in the metastatic setting, and promising trials in the adjuvant and advanced settings.

Merkel Cell Carcinoma in the Setting of Chronic Lymphocytic Leukemia and Diffuse Large B-Cell Lymphoma

Merkel cell carcinoma (MCC) is a rare, rapidly growing, and highly malignant cutaneous tumor that typically presents in elderly males as an erythematous or violaceous plaque or nodule in sun-exposed areas. Risk factors include long-term ultraviolet (UV) exposure, Merkel cell polyomavirus (MCV) infection, immunosuppression, and lymphoproliferative disorders such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Given the aggressive nature of this tumor, patients may present with nodal and distal metastasis. Locoregional disease can be managed with definitive radiotherapy or surgery with or without adjuvant radiotherapy, depending on the case. Disseminated disease, on the other hand, often requires a multidisciplinary tumor board consultation to individually tailor the treatment. Possible treatments include systemic therapy with chemotherapy or immunotherapy, radiotherapy, and surgery. Here we report a case of a patient with a medical history significant for chronic lymphocytic leukemia and diffuse large B-cell lymphoma who presented with a rapidly growing lesion that contained neighboring MCC and CLL/SLL on biopsy. Management included immunotherapy with pembrolizumab and radiotherapy to limit the tumor's growth and spread. To the best of our knowledge, the coexistence of all three malignancies in a person is rare and has not been reported previously. 

Immunotherapy in advanced Merkel cell carcinoma: Sydney west cancer network experience

INTRODUCTION

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer with no survival benefit demonstrated using palliative cytotoxic chemotherapy in the setting of metastatic MCC. Recently, immune checkpoint inhibitors (anti-PD-L1/PD1) have been approved in this setting after durable clinical response was demonstrated in several clinical trials. In this series, we present a multicentre real-world experience in using anti-PD-L1/PD1 in advanced MCC.

METHODS

A retrospective review was performed of all patients with metastatic MCC who were treated with at least one dose of anti-PD-L1/PD1 presenting to Sydney West Cancer Network (Westmead, Nepean and Blacktown hospitals) was performed between 2016 and 2020. Treatment response was assessed based on morphologic and/or metabolic changes of the disease on FDG-PET/CT scans. Primary end point investigated was objective response rate. Secondary outcomes included therapy toxicity, disease control and overall survival.

RESULTS

Thirteen patients received anti-PD-L1/PD1 with a median age of 82 (range 62-89). Two patients had undergone prior palliative chemotherapy. The median follow-up time was 17 months (range 2-34). The overall, complete and partial response rates were 77% (10), 54% (7) and 23% (3), respectively. Treatment-related grade 1 or 2 toxicity was experienced by 69% with only 2 cases of greater severity. The median progression-free survival and overall survival were 18 months (95% CI 10-26 months) and 33 months (95% CI range 7.6-58.4 months), respectively.

CONCLUSIONS

Consistent with clinical trial results, anti-PD-L1/PD1 therapy in this small series demonstrated efficacy and safety in patients with metastatic MCC.

Daily Lifestyle and Cutaneous Malignancies

Daily lifestyle is a fundamental part of human life and its influence accumulates daily in the human body. We observe that a good daily lifestyle has a beneficial impact on our health; however, the actual effects of individual daily lifestyle factors on human skin diseases, especially skin cancers, have not been summarized. In this review, we focused on the influence of daily lifestyle on the development of skin cancer and described the detailed molecular mechanisms of the development or regulation of cutaneous malignancies. Several daily lifestyle factors, such as circadian rhythm disruption, smoking, alcohol, fatty acids, dietary fiber, obesity, and ultraviolet light, are known to be associated with the risk of cutaneous malignancies, malignant melanoma, squamous cell carcinoma, basal cell carcinoma, and Merkel cell carcinoma. Although the influence of some daily lifestyles on the risk of skin cancers is controversial, this review provides us a better understanding of the relationship between daily lifestyle factors and skin cancers.

Not Your Typical Tonsil: Metastatic Merkel Cell Carcinoma or Primary Disease?

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumor that almost always presents as a cutaneous lesion in the sun-exposed areas on the bodies of elderly white males. Metastasis to lymph nodes in the presence or absence of a known primary site and occurrence of these tumors in non-sun-exposed sites have also been described; however, an incidence of recurrent disease arising in the palatine tonsil in the absence of any detectable primary lesion has never been reported in the literature. In this report, we discuss a case of a 72-year-old female who was found to have a single axillary lymph node, which was resected and proved to be positive forMCC of unknown primary (MCCUP). Since there was no evidence of additional disease, the patient elected not to pursue adjuvant therapies. Six and a half months later, she presented with a complaint of dysphagia and a right-sided exophytic tonsillar mass. Tonsillectomy revealed MCC with no detectable primary cutaneous lesion. She received adjuvant therapy with avelumab and demonstrated a complete response after one year of bi-weekly treatments. Seven months following cessation of adjuvant treatments, surveillance positron emission tomography (PET) revealed enlarged retroperitoneal, pretracheal, periaortic, and left axillary lymph nodes concerning for recurrence. She elected to forgo additional biopsies and restarted avelumab the following month. She continues to be followed up on a monthly basis.

Erythema Ab Igne: A Rare Presentation of Toasted Skin Syndrome With the Use of a Space Heater

Erythema ab igne, also known as toasted skin syndrome, is an acquired asymmetric hyperpigmented dermatosis that is caused by repeated exposure to moderate heat or infrared radiation. Hyperpigmentation is caused by the degeneration of elastic fibers and basal cells resulting in the release of melanin. Historically found in bakers and industrial workers, this condition has recently resurfaced in medical literature with the use of novel heat sources such as laptops and heated car seats. While this condition can resolve spontaneously after removal of heat exposure, delay in diagnosis and persistent exposure can lead to permanent pigmentation or progression to Merkel cell carcinoma, basal cell carcinoma, and squamous cell carcinoma.

Mutational Landscape of Virus- and UV-Associated Merkel Cell Carcinoma Cell Lines Is Comparable to Tumor Tissue

Simple Summary

Merkel cell carcinoma (MCC) is an aggressive, rare skin cancer which is caused either by a virus or chronic UV exposure. For both forms, distinct genetic alterations have been described; however, these observations were mostly made in tumor tissue. Since cancer cell lines are frequently used as preclinical models to investigate biological function, we considered it necessary to establish the genomic landscape of MCC cell lines by whole-exome sequencing. We confirmed the presence of UV-induced DNA damage, a high number of mutations and several coding mutations in virus-negative cell lines which were absent in virus-positive cell lines; these, however, harbored characteristic copy number variations, suggesting some virally caused genetic instability. Knowing the genomic features of MCC cell lines validates previous, and facilitates upcoming, experimental studies to discover their biological and translational relevance.

Abstract

Merkel cell carcinoma (MCC) is a rare, highly aggressive cutaneous malignancy that is either associated with the integration of the Merkel cell polyomavirus or chronic UV exposure. These two types of carcinogenesis are reflected in characteristic mutational features present in MCC tumor lesions. However, the genomic characteristics of MCC cell lines used as preclinical models are not well established. Thus, we analyzed the exomes of three virus-negative and six virus-positive MCC cell lines, all showing a classical neuroendocrine growth pattern. Virus-negative cell lines are characterized by a high tumor mutational burden (TMB), UV-light-induced DNA damage, functionally relevant coding mutations, e.g., in RB1 and TP53, and large amounts of copy number variations (CNVs). In contrast, virus-positive cell lines have a low TMB with few coding mutations and lack prominent mutational signatures, but harbor characteristic CNVs. One of the virus-negative cell lines has a local MYC amplification associated with high MYC mRNA expression. In conclusion, virus-positive and -negative MCC cell lines with a neuroendocrine growth pattern resemble mutational features observed in MCC tissue samples, which strengthens their utility for functional studies.

Anti-EGFR Antibody Plus Chemotherapy Treatment in a Patient with Synchronous Merkel Cell Carcinoma and Colorectal Cancer

Merkel cell carcinoma (MCC) is a rare neuroendocrine cutaneous malignancy. During early stages, surgery is the primary treatment followed by radiotherapy in patients at high risk of recurrence. Definitive radiation therapy is an alternative for patients who are not surgical candidates, reserving chemotherapy for metastatic disease. We present a case of a male patient diagnosed with MCC and stage IV colorectal cancer and we focus on the skin tumor shrinkage after specific colorectal cancer treatment.

Sex Differences in Overall Survival and the Effect of Radiotherapy in Merkel Cell Carcinoma-A Retrospective Analysis of a Swedish Cohort

Simple Summary

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer which is believed to be partially caused by a virus or ultraviolet exposure. Most previous studies have shown that MCC is more common in men compared to women, virus associated MCC has a better prognosis and surgery followed by radiotherapy gives a better outcome. In this article, we explore these traits in a Swedish cohort of 113 patients and find that MCC is more common in women and female patients have a longer survival compared to male patients. In addition, we found that virus negative MCC has a worse outcome in male patients and radiotherapy after surgery gives a better outcome for patients who are treated with a curative dosage, irrespective of sex.

Abstract

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer where Merkel cell Polyomavirus (MCPyV) contributes to the pathogenesis. In an adjuvant setting, radiotherapy (RT) is believed to give a survival benefit. The prognostic impact of sex related to MCPyV-status and adjuvant RT were analyzed in patients referred to Karolinska University Hospital. Data were collected from 113 patients’ hospital records and MCPyV analyses were made in 54 patients (48%). We found a significantly better overall survival (OS) for women compared to men and a significant difference in OS in patients receiving adjuvant RT. Furthermore, we found that men with virus negative MCC have an increased risk for earlier death (HR 3.6). This indicates that MCPyV positive and negative MCC act as two different diseases, and it might be due to different mechanism in the immune response between male and female patients. This could have significance in tailoring treatment and follow-up in MCC patients in the future.

Evidence and Considerations on Treatment of Small Size Merkel Cell Head and Neck Carcinoma

Introduction  Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine malignant cancer. It is an epidermal cancer common in the head and neck.

Objectives  Though there is limited number of cases described in the literature for the treatment difficult to obtain. Our purpose was to present the clinical course and treatment of four patients with MCC.

Methods  We conducted a retrospective analysis and obtained detailed clinical information for all 4 patients treated for MCC at the ENT Department of the SS Annunziata Hospital in Chieti, Italy, from 2013 through 2015.

Results  In our study, two patients presented with the tumor in a rare site (lower eyelid). All of the patients underwent surgical treatment: three patients had free excision margins and negative sentinel lymph nodes (SLNs) while 1 patient had free excision margins and positive SLNs. The latter patient underwent ipsilateral neck dissection. In another patient, the fluorodeoxyglucose positron emission topography (FDG PET)/computed tomography (CT) performed 6 months after the surgery has shown high metabolic activity in the left parotid gland, and the patient underwent total parotidectomy and a neck dissection.

Conclusion  Sentinel lymph node biopsy is a useful technique in small size MCCs of the head and neck. However, the parotid gland should be strictly controlled in patients with lower eyelid tumors.

LSD1 inhibition induces differentiation and cell death in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a highly aggressive, neuroendocrine skin cancer that lacks actionable mutations, which could be utilized for targeted therapies. Epigenetic regulators governing cell identity may represent unexplored therapeutic entry points. Here, we targeted epigenetic regulators in a pharmacological screen and discovered that the lysine‐specific histone demethylase 1A (LSD1/KDM1A) is required for MCC growth in vitro and in vivo. We show that LSD1 inhibition in MCC disrupts the LSD1‐CoREST complex leading to displacement and degradation of HMG20B (BRAF35), a poorly characterized complex member that is essential for MCC proliferation. Inhibition of LSD1 causes derepression of transcriptional master regulators of the neuronal lineage, activates a gene expression signature resembling normal Merkel cells, and induces cell cycle arrest and cell death. Our study unveils the importance of LSD1 for maintaining cellular plasticity and proliferation in MCC. There is also growing evidence that cancer cells exploit cellular plasticity and dedifferentiation programs to evade destruction by the immune system. The combination of LSD1 inhibitors with checkpoint inhibitors may thus represent a promising treatment strategy for MCC patients.

Association of Programmed Death 1 Protein Ligand (PD-L1) Expression With Prognosis in Merkel Cell Carcinoma

Background: Merkel cell carcinoma (MCC) is a rare neuroendocrine skin cancer. Prior to the advent of immunotherapy, treatment options were limited. In our study, we evaluate the impact of tumor cell PD-L1 expression and tumor immune microenvironment on survival in MCC patients who were not treated with immune checkpoint inhibitors.

Methods: Clinical data and tissue samples were collected from 78 patients with confirmed MCC treated at Dana-Farber Cancer Institute. Specimens were analyzed for the distribution of PD-L1 by immunohistochemistry staining (IHC) and standardized analysis. Results were correlated with survival data.

Results: In this study, membrane and cytoplasmic MCC tumor cell staining for PD-L1 was detected in 22.4% (15 of 67) of cases and PD-L1 staining of intratumoral microvessels and PD-L1 positive immune cells at the infiltrative margins of the tumor in 92.5% (62 of 67) of cases. In patients untreated with immune checkpoint inhibitors, median overall survival was not different for patients based on PD-L1 expression (PD-L1+ 64 months vs. PD-L1- not reached; HR = 1.26, 95% CI: 0.46–3.45; p = 0.60).

Conclusion: PD-L1 expression is frequently detected in MCC tumor cells and tumor microenvironment. PD-L1 expression did not affect prognosis in this cohort that had not received PD-1/L1 blockade.

Frequency and prognosis of metastasis to liver, lung, bone and brain from Merkel cell carcinoma

Aim: To describe the factors affecting distant metastasis of Merkel cell carcinoma (MCC) and the prognosis of metastatic MCC. Materials & methods: The MCC patient information was downloaded from the SEER database. Logistic regression and Cox proportional hazard models were conducted to screen for significant factors. Results: A total of 3449 patients were enrolled. Surgery and chemotherapy were significantly correlated with the occurrence of distant metastasis. In the cause-specific survival rate of MCC, regional lymph node removal, sentinel lymph node biopsy, radiation and chemotherapy can significantly reduce the prognostic risk of patients with distant metastases. Conclusion: Our study screened out the factors affecting the distant metastasis and prognosis of MCC and more prospective studies are needed to verify our findings.

Clinical Relevance of Liquid Biopsy in Melanoma and Merkel Cell Carcinoma

Melanoma and Merkel cell carcinoma are two aggressive skin malignancies with high disease-related mortality and increasing incidence rates. Currently, invasive tumor tissue biopsy is the gold standard for their diagnosis, and no reliable easily accessible biomarker is available to monitor patients with melanoma or Merkel cell carcinoma during the disease course. In these last years, liquid biopsy has emerged as a candidate approach to overcome this limit and to identify biomarkers for early cancer diagnosis, prognosis, therapeutic response prediction, and patient follow-up. Liquid biopsy is a blood-based non-invasive procedure that allows the sequential analysis of circulating tumor cells, circulating cell-free and tumor DNA, and extracellular vesicles. These innovative biosources show similar features as the primary tumor from where they originated and represent an alternative to invasive solid tumor biopsy. In this review, the biology and technical challenges linked to the detection and analysis of the different circulating candidate biomarkers for melanoma and Merkel cell carcinoma are discussed as well as their clinical relevance.

Robot-assisted inguinal lymphadenectomy: preliminary experience and perioperative outcomes from an Italian referral center

Background

Inguinal lymphadenectomy remains the gold standard for the treatment of inguinal lymph node metastases from penile carcinoma, melanoma, Merkel cell carcinoma, and squamous cell carcinoma (SCC). This procedure is associated with significant complications. In order to reduce morbidity, minimally invasive approaches have been described. We report our preliminary experience with robot-assisted inguinal lymphadenectomies (RAIL).

Methods

RAIL was performed according to the Sotelo technique. When indicated, a robot-assisted pelvic lymphadenectomy (RAPLND) was performed. We recorded age, sex, comorbidities, baseline oncologic diagnosis, operative time, hospital stay, lymph node yield, complications, time to drain removal, and oncologic outcomes.

Results

From December 2016 to February 2019, 13 patients underwent RAIL. Median age was 65 years (range: 31-85 years). Primary malignancy was melanoma in five patients, Merkel cell carcinoma in four, dermal duct tumor in one, penile cancer in two, and SCC in one. RAIL was monolateral in 12 cases and bilateral in 1 case. A total of 10 monolateral RAPLNDs were performed; median operative time was 279 min (range: 169-320). Median lymph nodes yield was 11 (range: 2-24) for monolateral RAIL and 9 for monolateral RAPLND (range 2-24). Median hospital stay was 4 days (range: 2-5). No procedure was converted to open. Median follow up was 16 months (range: 5-31). Five Clavien-Dindo grade I complications were recorded. Median time to drain removal was 32.5 days (range 7-65). Three recurrences and two cancer-related deaths were recorded.

Conclusions

RAIL is feasible and associated with a short hospital stay, with little incidence of perioperative complications.

Spinal Metastasis from Merkel Cell Carcinoma in an Elderly Male

Merkel cell carcinoma is a cutaneous neuroendocrine malignancy that has an aggressive nature. Classically, it affects the elderly Caucasian population with a predilection for the sun-exposed areas of the body. Pathogenesis has been linked to ultraviolet radiation, immunosuppression, and the Merkel cell polyomavirus. Definitive diagnosis entails histologic evaluation and immunohistochemical staining. With its generalized appearance and tendency for metastasis, a high index of suspicion must be utilized. In this case, we present the unique presentation of Merkel cell carcinoma as a rapidly enlarging lymph node with metastatic disease to the spinal column presenting as new-onset low back and radicular pain.

Mild Hypofractionated Radiation Therapy for Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine neoplasm. Although surgical resection is the first-line treatment for primary MCCs, the characteristics of this disease (i.e., high prevalence in the elderly and in the head and neck region) generate a considerable number of inoperable cases. Radiation therapy shows potential as a definitive treatment alternative to surgery. In definitive radiation therapy for non-resected MCC, 60-66 Gy administered in 2 Gy per fraction and five fractions per week is recommended. However, such frequent visits to the hospital can be a great burden to elderly patients and family members. In this report, we present the case of an 89-year-old patient with MCC (cT2N0M0, stage IIA) of the left cheek. The patient was treated with radiation therapy using a mild hypofractionated schedule (57 Gy provided in 3 Gy per fraction and three fractions per week) targeting the gross tumor. The treatment led to complete tumor remission with well-tolerated acute toxicities at three months post-irradiation. This case indicates that a mild hypofractionated irradiation schedule may achieve tumor control in MCC patients who are inoperable and who cannot make frequent hospital visits.