68Ga-DOTATATE PET/CT Imaging of a Solitary Nasopharyngeal Metastasis of Merkel Cell Carcinoma.

ABSTRACT: Merkel cell carcinoma (MCC) is an uncommon highly aggressive cutaneous neuroendocrine neoplasm with high mortality. Rarer still is nasopharyngeal metastasis of MCC. Herein, we report the 68Ga-DOTATATE PET/CT findings of MCC with metastasis to the nasopharynx in a 53-year-old man who underwent surgery for MCC in his thigh 2 years ago.

A Rapidly Developing Nodule in a Patient With Hairy Cell Leukemia in Remission: Merkel Cell Carcinoma: A Case Report.

BACKGROUND/AIM: Hairy cell leukemia (HCL) is a well-known lymphoproliferative disease with very effective treatment approaches primarily relying on purine analogues. However, these treatments are associated with profound and prolonged immunosuppression. Merkel cell carcinoma (MCC) is a rare and extremely aggressive skin tumor with an increased incidence in immunocompromised patients. CASE REPORT: We report a case of a patient with HCL who was diagnosed with MCC, while in remission following retreatment with pentostatin, which induced a profound decrease in CD4 (+) T-cells. CONCLUSION: Our case provides further evidence supporting the hypothesis of a significant association between immunosuppression and MCC pathogenesis.

Current status of Merkel cell carcinoma: Epidemiology, pathogenesis and prognostic factors.

Merkel cell carcinoma (MCC) is an extremely rare cutaneous neuroendocrine cancer, with an incidence approximately 40 times lower than that of malignant melanoma; however, its significantly inferior survival rate compared to melanoma establishes MCC as the most lethal form of skin cancer. In recent years, a substantial body of literature has demonstrated a gradual increase in the incidence of MCC. Although the two factors that contribute to MCC, ultraviolet radiation and Merkel cell polyomavirus infection, have been well established, the specific pathogenesis of this disease remains unclear. Additionally, considering the high lethality and recurrence rates of MCC, as well as the absence of specific antitumor drugs, it is crucial to elucidate the factors that can accurately predict patients' outcomes. In this review, we summarized the significant advancements in the epidemiological characteristics, pathogenesis, and the factors that influence patient prognosis of MCC to enhance clinical practices and public health efforts.

Avelumab as second-line or later treatment in patients with metastatic Merkel cell carcinoma: Analysis of real-world outcomes in France using the CARADERM database linked to the French national healthcare database.

AIM: Avelumab has been approved worldwide for treatment of metastatic Merkel cell carcinoma (mMCC), a rare and aggressive skin cancer. This study evaluated outcomes in patients with mMCC in France who received avelumab as second-line or later (2L+) treatment in routine clinical practice. METHODS: This retrospective, noninterventional study evaluated all patients diagnosed with mMCC using two databases: CARADERM (French national database of rare dermatological cancers) and SNDS (national healthcare database), identified via probabilistic linkage. Eligible patients initiated avelumab as 2L+ treatment between August 2016 and December 2019 and were followed for 24 months. The primary endpoint was overall survival (OS) at 24 months. RESULTS: Overall, 180 patients who received 2L+ avelumab were identified (112 from CARADERM, 68 after SNDS linkage). Median age at diagnosis was 74.0 years and 177 (98.3 %) had received chemotherapy alone as first-line treatment. Median follow-up was 13.1 months. Median OS from start of avelumab was 14.6 months (95 % CI, 9.9-21.3) in the overall population, 15.9 months (95 % CI, 8.6-28.3) in CARADERM patients, and 13.3 months (95 % CI, 6.7-19.1) in non-CARADERM patients. OS rates at 12 and 24 months were 53.8 % (95 % CI, 46.2 %-60.8 %) and 40.5 % (95 % CI, 33.2 %-47.6 %), respectively. In evaluable patients (CARADERM database), median progression-free survival was 3.6 months (95 % CI, 2.7-7.5) and the objective response rate was 55.3 % (95 % CI, 45.3-65.4), including complete response in 31.9 %. CONCLUSIONS: Real-world outcomes with 2L+ avelumab treatment for mMCC are consistent with clinical trial findings, supporting the recommendation of avelumab as a standard of care.

Merkel Cell Carcinoma With Extensive Bone Marrow Metastasis and Peripheral Blood Involvement: A Case Report With Immunohistochemical and Mutational Studies.

Merkel cell carcinoma (MCC) is a rare, highly aggressive skin cancer of neuroendocrine origin that is typically associated with either the presence of Merkel cell polyomavirus or chronic exposure to ultraviolet (UV) light. We report a case of relapsed MCC that presented with new symptoms of fatigue, back pain, and myeloid left shift identified during scheduled follow-up. The patient was found to have circulating neoplastic cells in the peripheral blood and bone marrow metastasis. Immunohistochemistry for synaptophysin, CD56, INSM-1, CK20, CD117 were positive, whereas CD34, TdT, Chromogranin, CD10, myeloperoxidase, CD3 and CD19 were negative. Flow cytometry of the peripheral blood confirmed the presence of an abnormal nonhematopoietic cell population expressing CD56 positivity. A next-generation sequencing (NGS) panel revealed the presence of variants in RB1, TP53, and other genes, some of which have not been previously described in MCC. This rare presentation highlights the challenges in the diagnosis and management of MCC.

Quality of life and patient-reported toxicities in patients with advanced Merkel cell carcinoma treated with combined nivolumab and ipilimumab with or without stereotactic body radiation therapy.

BACKGROUND: Merkel cell carcinoma is a rare skin cancer associated with poor survival. Based on a previous Phase II trial of adults with advanced Merkel cell carcinoma by Kim and colleagues (2022), there is now a strong rationale for combination therapy (i.e., nivolumab and ipilimumab) to become a treatment option for patients with advanced Merkel cell carcinoma. The goal of this paper was to report on the secondary outcome of quality of life (QOL) among patients on this trial. METHODS: Patients receiving combined nivolumab and ipilimumab, with or without stereotactic body radiation therapy (SBRT), completed the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 prior to starting treatment and every 2 weeks thereafter. Changes in QOL during treatment and post-treatment were evaluated using piecewise random-effects mixed models. Exploratory analyses compared changes in QOL between study arms. The original trial was registered with ClinicalTrials.gov (NCT03071406). RESULTS: Study participants (n = 50) reported no changes in overall QOL (ps > 0.05), but emotional functioning improved during treatment (p = 0.01). Cognitive and social functioning worsened post-treatment (ps < 0.01). In general, patients treated with combination therapy only (n = 25) reported no change in QOL over time, whereas patients also treated with SBRT (n = 25) consistently demonstrated worsening QOL post-treatment. CONCLUSION: QOL is generally preserved in patients treated with combination therapy, but the addition of SBRT may worsen QOL. Combined with clinical efficacy data published previously, results support the use of combination therapy with nivolumab and ipilimumab as a treatment option for patients with advanced Merkel cell carcinoma.

The Clinical Utility of Teledermatology in Triaging and Diagnosing Skin Malignancies: Case Series.

With the increasing utilization of telemedicine since the COVID-19 pandemic, it is critical that clinicians have an appropriate understanding of the application of virtual care resources, including teledermatology. We present a case series of 3 patients to demonstrate the clinical utility of teledermatology in reducing the time to diagnosis of various rare and/or aggressive cutaneous malignancies, including Merkel cell carcinoma, malignant melanoma, and atypical fibroxanthoma. Cases were obtained from one large Midwestern medical center during the month of July 2021. Each case presented includes a description of the initial teledermatology presentation and reviews the clinical timeline from initial consultation submission to in-person clinic visit with lesion biopsy. This case series demonstrates real-world examples of how teledermatology can be utilized to expedite the care of specific vulnerable patient populations.

Analyses of combined Merkel cell carcinomas with neuroblastic components suggests that loss of T antigen expression in Merkel cell carcinoma may result in cell cycle arrest and neuroblastic transdifferentiation.

Merkel cell carcinoma (MCC) is an aggressive skin cancer frequently caused by genomic integration of the Merkel cell polyomavirus (MCPyV). MCPyV-negative cases often present as combined MCCs, which represent a distinctive subset of tumors characterized by association of an MCC with a second tumor component, mostly squamous cell carcinoma. Up to now, only exceptional cases of combined MCC with neuroblastic differentiation have been reported. Herein we describe two additional combined MCCs with neuroblastic differentiation and provide comprehensive morphologic, immunohistochemical, transcriptomic, genetic and epigenetic characterization of these tumors, which both arose in elderly men and appeared as an isolated inguinal adenopathy. Microscopic examination revealed biphasic tumors combining a poorly differentiated high-grade carcinoma with a poorly differentiated neuroblastic component lacking signs of proliferation. Immunohistochemical investigation revealed keratin 20 and MCPyV T antigen (TA) in the MCC parts, while neuroblastic differentiation was confirmed in the other component in both cases. A clonal relation of the two components can be deduced from 20 and 14 shared acquired point mutations detected by whole exome analysis in both combined tumors, respectively. Spatial transcriptomics demonstrated a lower expression of stem cell marker genes such as SOX2 and MCM2 in the neuroblastic component. Interestingly, although the neuroblastic part lacked TA expression, the same genomic MCPyV integration and the same large T-truncating mutations were observed in both tumor parts. Given that neuronal transdifferentiation upon TA repression has been reported for MCC cell lines, the most likely scenario for the two combined MCC/neuroblastic tumors is that neuroblastic transdifferentiation resulted from loss of TA expression in a subset of MCC cells. Indeed, DNA methylation profiling suggests an MCC-typical cellular origin for the combined MCC/neuroblastomas. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Mast cell density in Merkel cell carcinoma and its correlation with prognostic features and MCPyV status: a pilot study.

Merkel cell carcinoma (MCC) is a rare, highly aggressive, primitive neuroendocrine carcinoma of the skin, the origin of which is not yet fully understood. Numerous independent prognostic factors have been investigated in an attempt to understand which are the most important parameters to indicate in the histological diagnostic report of MCC. Of these, mast cells have only been studied in one paper before this one. We present a retrospective descriptive study of 13 cases of MCC, received at the Department of Pathology over a 20-year period (2003-2023 inclusive) on which we performed a study using whole-slide (WSI) morphometric analysis scanning platform Aperio Scanscope CS for the detection and spatial distribution of mast cells, using monoclonal anti-tryptase antibody and anti-CD34 monoclonal antibody to study the density of microvessels. In addition, we analyzed MCPyV status with the antibody for MCPyV large T-antigen (Clone CM2B4). We found statistically significant correlation between mast cell density and local recurrence/distant metastasis/death-of-disease (p = 0.008). To our knowledge, we firstly reported that MCPyV ( -) MCC shows higher mast cells density compared to MCPyV ( +) MCC, the latter well known to be less aggressive. Besides, the median vascular density did not show no significant correlation with recurrence/metastasis/death-of-disease, (p = 0.18). Despite the small sample size, this paper prompts future studies investigating the role of mast cell density in MCC.

Preexisting Skin-Resident CD8 and γδ T-cell Circuits Mediate Immune Response in Merkel Cell Carcinoma and Predict Immunotherapy Efficacy.

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer with a ∼50% response rate to immune checkpoint blockade (ICB) therapy. To identify predictive biomarkers, we integrated bulk and single-cell RNA sequencing (RNA-seq) with spatial transcriptomics from a cohort of 186 samples from 116 patients, including bulk RNA-seq from 14 matched pairs pre- and post-ICB. In nonresponders, tumors show evidence of increased tumor proliferation, neuronal stem cell markers, and IL1. Responders have increased type I/II interferons and preexisting tissue resident (Trm) CD8 or Vδ1 γδ T cells that functionally converge with overlapping antigen-specific transcriptional programs and clonal expansion of public T-cell receptors. Spatial transcriptomics demonstrated colocalization of T cells with B and dendritic cells, which supply chemokines and costimulation. Lastly, ICB significantly increased clonal expansion or recruitment of Trm and Vδ1 cells in tumors specifically in responders, underscoring their therapeutic importance. These data identify potential clinically actionable biomarkers and therapeutic targets for MCC. Significance: MCC serves as a model of ICB response. We utilized the largest-to-date, multimodal MCC dataset (n = 116 patients) to uncover unique tumor-intrinsic properties and immune circuits that predict response. We identified CD8 Trm and Vδ1 T cells as clinically actionable mediators of ICB response in major histocompatibility complex-high and -low MCCs, respectively.

Circulating Tumor DNA Assay Detects Merkel Cell Carcinoma Recurrence, Disease Progression, and Minimal Residual Disease: Surveillance and Prognostic Implications.

PURPOSE: Merkel cell carcinoma (MCC) is an aggressive skin cancer with a 40% recurrence rate, lacking effective prognostic biomarkers and surveillance methods. This prospective, multicenter, observational study aimed to evaluate circulating tumor DNA (ctDNA) as a biomarker for detecting MCC recurrence. METHODS: Plasma samples, clinical data, and imaging results were collected from 319 patients. A tumor-informed ctDNA assay was used for analysis. Patients were divided into discovery (167 patients) and validation (152 patients) cohorts. Diagnostic performance, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), was assessed. RESULTS: ctDNA showed high sensitivity, 95% (discovery; 95% CI, 87 to 99) and 94% (validation; 95% CI, 85 to 98), for detecting disease at enrollment, with corresponding specificities of 90% (95% CI, 82 to 95) and 86% (95% CI, 77 to 93). A positive ctDNA during surveillance indicated increased recurrence risk, with hazard ratios (HRs) of 6.8 (discovery; 95% CI, 2.9 to 16) and 20 (validation; 95% CI, 8.3 to 50). The PPV for clinical recurrence at 1 year after a positive ctDNA test was 69% (discovery; 95% CI, 32 to 91) and 94% (validation; 95% CI, 71 to 100), respectively. The NPV at 135 days after a negative ctDNA test was 94% (discovery; 95% CI, 90 to 97) and 93% (validation; 95% CI, 89 to 97), respectively. Patients positive for ctDNA within 4 months after treatment had higher rates of recurrence, with 1-year rates of 74% versus 21% (adjusted HR, 7.4 [95% CI, 2.7 to 20]). CONCLUSION: ctDNA testing exhibited high prognostic accuracy in detecting MCC recurrence, suggesting its potential to reduce frequent surveillance imaging. ctDNA also identifies high-risk patients who need more frequent imaging and may be best suited for adjuvant therapy trials.

Merkel cell carcinoma associated with TNF inhibitor therapy: a systematic review of case reports.

A rare neuroendocrine skin cancer called Merkel cell carcinoma (MCC) primarily affects elderly people. The objective of this study is to comprehensively review the impact of immunosuppressive medications, particularly TNF inhibitors, on the emergence of MCC. METHODS: PubMed, Web of Science, Science Direct, and Cochrane Library were searched. Study articles were screened by title and abstract at Rayyan Qatar Computing Research Institute, then a full-text assessment was implemented. RESULTS: A total of eight case reports with 9 patients were included. Of the total population, seven were women and only two were men. Their age ranged from 31 to 73 years. More than half the population (5 cases) were being treated for rheumatoid arthritis. All received TNF inhibitors that were associated with the induction of MCC. CONCLUSION: We found that it is essential for physicians to explain potential cancer risks to patients before starting long-term immunosuppressive therapy and to conduct routine checks for MCC and other side effects. TNF inhibitors (infliximab, adalimumab, etanercept, and golimumab) were all associated with MCC development. Women constituted the majority of cases and most were elderly.

Dermoscopic characteristics of Merkel cell carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare, aggressive, cutaneous tumour with high mortality and frequently delayed diagnosis. Clinically, it often manifests as a rapidly growing erythematous to purple nodule usually located on the lower extremities or face and scalp of elderly patients. There is limited available data on the dermoscopic findings of MCC, and there are no specific features that can be used to definitively diagnose MCC. AIM OF THE STUDY: Here, we aimed to summarize existing published literature on dermatoscopic and reflectance confocal microscopy (RCM) features of MCC. MATERIALS AND METHODS: To find relevant studies, we searched the PubMed and Scopus databases from inception to April 12, 2023. Our goal was to identify all pertinent research that had been written in English. The following search strategy was employed: (" dermoscopy" OR " dermatoscopy" OR " videodermoscopy" OR " videodermatoscopy" OR " reflectance confocal microscopy") AND " Merkel cell carcinoma". Two dermatologists, DK and GE, evaluated the titles and abstracts separately for eligibility. For inclusion, only works written in English were taken into account. RESULTS: In total 16 articles were retrieved (68 cases). The main dermoscopic findings of MCC are a polymorphous vascular pattern including linear irregular, arborizing, glomerular, and dotted vessels on a milky red background, with shiny or non-shiny white areas. Pigmentation was lacking in all cases. The RCM images showed a thin and disarranged epidermis, and small hypo-reflective cells that resembled lymphocytes arranged in solid aggregates outlined by fibrous tissue in the dermis. Additionally, there were larger polymorphic hyper-reflective cells that likely represented highly proliferative cells. CONCLUSION: Dermoscopic findings of MCC may play a valuable role in evaluating MCC, aiding in the early detection and differentiation from other skin lesions. Further prospective case-control studies are needed to validate these results.

Merkel Cell Carcinoma.

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer that is highly radiosensitive and immunogenic. Immunotherapy is the primary treatment of advanced disease, and immune checkpoint inhibitors show promise as neoadjuvant or adjuvant therapy in patients with high-risk resectable MCC. Emerging biomarkers of tumor burden are becoming increasingly important in identifying high-risk patients and in post-treatment surveillance. Further research is needed to determine the optimal duration of anti-PD-(L)1 treatment and second-line options for patients with MCC refractory to immunotherapy. This review covers the characteristics and management of MCC including recent innovations and areas of active investigation.

The Role of Neoadjuvant Immunotherapy in the Management of Merkel Cell Carcinoma with Clinically Detected Regional Lymph Node Metastasis.

BACKGROUND: Immunotherapy is emerging as a promising option for certain locally advanced and metastatic cutaneous malignancies. However, the role of neoadjuvant immunotherapy (NIO) in Merkel cell carcinoma (MCC) with clinically detected regional lymph node metastasis (CDRLNM) has not been fully elucidated. METHODS: For this study, MCC patients with CDRLNM who underwent surgical excision were selected from the National Cancer Database (NCDB). Those who received NIO were propensity-matched with those who did not, and Kaplan-Meier analysis was used to compare overall survival (OS). RESULTS: Of the 1809 selected patients, 356 (19.7%) received NIO followed by wide excision (n = 352, 98.9%) or amputation (n = 4, 1.1%). The rate of complete pathologic response for the primary tumor (ypT0) was 45.2%. Only 223 patents (63.4%) also underwent lymph node dissection (LND). The complete pathologic nodal response (ypN0) rate for these patients was 17.9%. A pathologic complete response of both the primary tumor and the nodal basin (ypT0 ypN0) was seen in 16 of the 223 patients who underwent both primary tumor surgery and LND. Subsequently, 151 pairs were matched between the NIO and no-NIO groups (including only patients with LND). Kaplan-Meier analysis demonstrated a significant OS improvement with NIO (median not reached vs. 35.0 ± 8.0 months; p = 0.025). The 5-year OS was 57% in the NIO group versus 44% in no-NIO group (p = 0.021). CONCLUSION: The study suggests that NIO in MCC with CDRLNM provides improved OS in addition to promising rates of primary complete response, which could change the profile of surgical resection. This supports ongoing clinical trials exploring the use of NIO in MCC.

Localized Merkel cell carcinoma treatment considerations: a response to the forty-year experience at the Peter MacCallum cancer centre.

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine tumour of the skin with poor prognosis and rising global incidence. A recently published article in BMC Cancer, titled "Merkel cell carcinoma: a forty-year experience at the Peter MacCallum Cancer Centre" (Wang et al.), provides a contemporary analysis of locoregional disease outcomes in Australia which highlights the comparative effectiveness of radiotherapy for excisions with involved margins versus wide local excision. There is a persistent lack of clear, well-defined guidelines to manage MCC in Australia despite experiencing the highest rates globally. The advanced age at onset also provides inherent challenges for optimal management and often, a case-by-case approach is necessary based on patient preferences, baseline function and fitness for surgery. This paper responds to the recently published article by Wang et al. and will expand the discourse regarding management of localized MCC. Specifically, we will discuss the surgical excision approaches; alternative treatment options for MCC including radiotherapy, Mohs micrographic surgery and novel immunotherapy agents being investigated through several clinical trials.

High-Risk Non-Melanoma Skin Cancers: Biological and Therapeutic Advances.

Nonmelanoma skin cancers (NMSCs) are the most common cancers, with high-risk NMSCs sharing features such as poor histologic differentiation, invasion into deeper layers, and anatomic location. NMSC includes basal cell carcinoma, cutaneous squamous cell carcinoma, and Merkel cell carcinoma. Herein, the authors describe advances in understanding the genetic mechanisms of malignant transformation and the composition of tumor microenvironment for these cancers. They summarize recent therapeutic advances, including targeted therapy and immunotherapy for NMSCs. Effective skin protection against ultraviolet radiation-induced carcinogenesis remains an urgent unmet need for NMSC prevention. The authors highlight immune-based interventions as novel strategies to address this need.