Basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and Merkel cell carcinoma (MCC) comprise the majority of nonmelanoma skin cancers. Advances have been made in treatment. Sentinel node biopsy should be considered for locally advanced, clinically node-negative cSCCs and MCCs. BCC patients failing traditional surgery and/or radiation are candidates for systemic hedgehog inhibitor therapy. Immune checkpoint inhibitor treatment is available for patients who failed traditional treatment with surgery and/or radiation or who are not candidates for these modalities. Specifically, cemiplimab is approved for advanced BCC; cemiplimab and pembrolizumab for advanced cSCC; and avelumab, pembrolizumab, and retifanlimab-dlwr for recurrent/metastatic MCC.

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Patients with cutaneous malignancies and locoregional involvement represent a high-risk population for disease recurrence, even if they receive optimal surgery and adjuvant treatment. Here, we discuss how neoadjuvant therapy has the potential to offer significant advantages over adjuvant treatment, further improving outcomes in some patients with skin cancers, including melanoma, Merkel cell carcinoma, and cutaneous squamous-cell carcinoma. Both preclinical studies and in vivo trials have demonstrated that exposure to immunotherapy prior to surgical resection can trigger a broader and more robust immune response, resulting in increased tumor cell antigen presentation and improved targeting by immune cells, potentially resulting in superior outcomes. In addition, neoadjuvant approaches hold the possibility of providing a platform for evaluating pathological responses in the resected lesion, optimizing the prognosis and enabling personalized adaptive management, in addition to expedited drug development. However, more data are still needed to determine the ideal patient selection and the best treatment framework and to identify reliable biomarkers of treatment responses. Although there are ongoing questions regarding neoadjuvant treatment, current data support a paradigm shift toward considering neoadjuvant therapy as the standard approach for selecting patients with high-risk skin tumors.

OBJECTIVE: 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.
METHODS: 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.
CONCLUSIONS: Our case provides further evidence supporting the hypothesis of a significant association between immunosuppression and MCC pathogenesis.

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer influenced by the immune system. Recent studies suggest that viral infections, notably COVID-19, may exacerbate such malignancies. This case report explores potential mechanisms by which SARS-CoV-2, the virus responsible for COVID-19, could influence the behavior and proliferation of malignant tumor cells. Emerging evidence indicates that COVID-19 may disrupt immune surveillance and modulation, which are critical in controlling the spread and severity of cancers, including MCC. Additionally, the cytokine storm induced by COVID-19 is proposed to facilitate tumorigenic activity, potentially enhancing MCC aggressiveness. By integrating clinical findings with contemporary immunological and virological theories, this report aims to contribute to the understanding of COVID-19\'s impact on cancer progression, specifically MCC, emphasizing the need for comprehensive management strategies in cancer patients during the pandemic.

UNASSIGNED: Merkel cell carcinoma (MCC) presents challenges in surveillance due to varied recurrence rates and uncertain follow-up protocols, especially in late recurrent cases. These cases need personalized monitoring strategies beyond traditional timelines, such as clinical and molecular factors, in order to optimize patient outcomes.
UNASSIGNED: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with neuroendocrine differentiation with a propensity for recurrence following initial treatment. Surveillance strategies for MCC patients lack specificity, and the duration of surveillance remains uncertain, posing challenges in identifying appropriate follow-up intervals. Therefore, we present a 94-year-old woman, with history of stage IA MCC in her left nasal wall 21 years prior, that presented with a dome-shaped eroded nodule on her left fifth finger. Biopsy showed characteristic MCC features with positive immunohistochemistry for CD56, synaptophysin, and CK20 (perinuclear dotting). The patient opted against further imaging or lymph node biopsy and underwent Mohs micrographic surgery. To date, there has not been any evidence of recurrence at previous sites or development of new primary lesions. This case underscores the need for ongoing surveillance despite long disease-free intervals. It also stands out as the case demonstrating the longest latency/recurrence-free interval following the initial diagnosis of MCC in the literature. While most recurrences occur within the first few years post-diagnosis, our case highlights the exceptional nature of late recurrences and prompts reevaluation of surveillance protocols. Current guidelines recommend surveillance for up to 3 years post-treatment, but factors, such as patient demographics and tumor characteristics, may warrant extended monitoring periods. Emerging biomarkers, such as Merkel cell polyomavirus status and circulating tumor DNA, show promise in predicting and monitoring recurrences, but their utility in late recurrence detection requires further investigation.

Merkel cell carcinoma is a very aggressive primary skin tumour with a high risk of local recurrences and lymphatic and distant metastases. The frequent association between this carcinoma and other skin tumour and lymphoid malignancies, its similar cellular morphology with leukocytes, and limited infiltration in bone marrow constituted a challenging diagnosis. We report an unusual case of an 82-year-old male who simultaneously presented Merkel cell carcinoma and acute myeloid lymphoma. The diagnosis was established through flow cytometry, immunohistochemical studies and next generation sequencing (NGS) analysis. Flow cytometry allowed for the differentiation of the two cell populations in bone marrow aspirate, which was crucial to the diagnosis of Merkel cell carcinoma and acute myeloid leukaemia (AML), after confirmed by immunohistochemistry. AML could be classified based on NGS results. Following diagnosis, the patient received palliative care and died 50 days later. immunophenotypic analysis by flow cytometry and Immunohistochemical study was crucial to establish the diagnosis of simultaneous affection of Merkel cell carcinoma and hematologic disorder.

Tumor-stroma ratio (TSR) has been recognized as a valuable prognostic indicator in various solid tumors. This study aimed to examine the clinicopathologic relevance of TSR in Merkel cell carcinoma (MCC) using artificial intelligence (AI)-based parameterization of the stromal landscape and validate TSR scores generated by our AI model against those assessed by humans. One hundred twelve MCC cases with whole-slide images were collected from 4 different institutions. Whole-slide images were first partitioned into 128 × 128-pixel \"mini-patches,\" then classified using a novel framework, termed pre-tumor and stroma (Pre-TOAST) and TOAST, whose output equaled the probability of the minipatch representing tumor cells rather than stroma. Hierarchical random samplings of 50 minipatches per region were performed throughout 50 regions per slide. TSR and tumor-stroma landscape (TSL) parameters were estimated using the maximum-likelihood algorithm. Receiver operating characteristic curves showed that the area under the curve value of Pre-TOAST in discriminating classes of interest including tumor cells, collagenous stroma, and lymphocytes from nonclasses of interest including hemorrhage, space, and necrosis was 1.00. The area under the curve value of TOAST in differentiating tumor cells from related stroma was 0.93. MCC stroma was categorized into TSR high (TSR ≥ 50%) and TSR low (TSR < 50%) using both AI- and human pathology-based methods. The AI-based TSR-high subgroup exhibited notably shorter metastasis-free survival (MFS) with a statistical significance of P = .029. Interestingly, pathologist-determined TSR subgroups lacked statistical significance in recurrence-free survival, MFS, and overall survival (P > .05). Density-based spatial clustering of applications with noise analysis identified the following 2 distinct TSL clusters: TSL1 and TSL2. TSL2 showed significantly shorter recurrence-free survival (P = .045) and markedly reduced MFS (P < .001) compared with TSL1. TSL classification appears to offer better prognostic discrimination than traditional TSR evaluation in MCC. TSL can be reliably calculated using an AI-based classification framework and predict various prognostic features of MCC.

Polyomaviruses are small, circular dsDNA viruses that can cause cancer. Alternative splicing of polyomavirus early transcripts generates large and small tumor antigens (LT, ST) that play essential roles in viral replication and tumorigenesis. Some polyomaviruses also express middle tumor antigens (MTs) or alternate LT open reading frames (ALTOs), which are evolutionarily related but have distinct gene structures. MTs are a splice variant of the early transcript whereas ALTOs are overprinted on the second exon of the LT transcript in an alternate reading frame and are translated via an alternative start codon. Merkel cell polyomavirus (MCPyV), the only human polyomavirus that causes cancer, encodes an ALTO but its role in the viral lifecycle and tumorigenesis has remained elusive. Here, we show MCPyV ALTO acts as a tumor suppressor and is silenced in Merkel cell carcinoma (MCC). Rescuing ALTO in MCC cells induces growth arrest and activates NF-κB signaling. ALTO activates NF-κB by binding SQSTM1 and TRAF2&3 via two N-Terminal Activating Regions (NTAR1+2), resembling Epstein-Barr virus (EBV) Latent Membrane Protein 1 (LMP1). Following activation, NF-κB dimers bind the MCPyV noncoding control region (NCCR) and downregulate early transcription. Beyond MCPyV, NTAR motifs are conserved in other polyomavirus ALTOs, which activate NF-κB signaling, but are lacking in MTs that do not. Furthermore, polyomavirus ALTOs downregulate their respective viral early transcription in an NF-κB- and NTAR-dependent manner. Our findings suggest that ALTOs evolved to suppress viral replication and promote viral latency and that MCPyV ALTO must be silenced for MCC to develop.

We herein report four patients with periocular Merkel cell carcinoma treated with immune checkpoint inhibitors who experienced a dramatic response and, therefore, had less morbid surgery and/or avoided radiation therapy with its inherent ocular toxicity.