A better prognosis for Merkel cell carcinoma of unknown primary origin

Merkel cell carcinoma and the eye

Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine tumor with a poor five-year survival rate. Yearly cases have risen nearly 350% since the early 1980s, and these are predicted to increase as the overall US population ages. MCC of the eyelid is uncommon and can be misdiagnosed as other benign inflammatory and neoplastic eyelid disorders. Although MCC of the head and neck is often more aggressive than it is at other sites, eyelid MCC shows a lower disease-specific mortality rate. A biopsy is essential for accurate diagnosis, including an immunohistochemical panel of CK20 and TTF-1, although other markers may be necessary. Staging can be assessed clinically through physical examination findings and imaging and/or pathologically with sentinel lymph node biopsy or fine-needle aspiration. Pathologic staging more accurately predicts the prognosis. Eyelid MCC treatments include Mohs micrographic surgery to allow for complete clearance and adequate reconstruction of lost tissue, followed by adjuvant radiotherapy. In advanced disease, immunotherapies are preferred over traditional chemotherapy and are a subject of ongoing research.

Moderne Diagnostik und Therapie des Merkelzellkarzinoms

Das Merkelzellkarzinom (MCC) ist ein seltener, aggressiver Hauttumor mit epithelialer und neuroendokriner Differenzierung, dessen Inzidenz in den letzten Jahrzehnten deutlich zugenommen hat. Risikofaktoren sind fortgeschrittenes Lebensalter, heller Hauttyp, UV‐Exposition und Immunsuppression. Pathogenetisch wird ein durch das Merkelzell‐Polyomavirus (MCPyV) hervorgerufener Typ von einem UV‐induzierten Typ mit hoher Tumormutationslast unterschieden.

Klinisch präsentiert sich das MCC als meist schmerzloser, schnell wachsender, rötlich‐violetter Tumor mit glänzender Oberfläche, der bevorzugt im Kopf‐Hals‐Bereich und an den distalen Extremitäten lokalisiert ist. Eine sichere Diagnose kann nur anhand histologischer und immunhistochemischer Merkmale gestellt werden. Bei Erstdiagnose weisen 20%–26% der Patienten lokoregionäre Metastasen und 8%–14% Fernmetastasen auf, weshalb eine Ausbreitungsdiagnostik unabdingbar ist. Bei fehlenden klinischen Hinweisen auf Metastasen wird eine Sentinel‐Lymphknotenbiopsie empfohlen.

Wesentliche Säulen der Therapie sind die Operation, die adjuvante oder palliative Strahlentherapie und in fortgeschrittenen inoperablen Stadien die medikamentöse Tumortherapie. Die Einführung von Immuncheckpoint‐Inhibitoren führte zu einem Paradigmenwechsel, da sich hiermit ein wesentlich langfristigeres Ansprechen und bessere Überlebensraten als mit Chemotherapie erreichen lassen. Zur Therapie des metastasierten MCC ist in Deutschland der PD‐L1‐Inhibitor Avelumab zugelassen, aber auch die PD‐1‐Antikörper Pembrolizumab und Nivolumab werden mit Erfolg eingesetzt. Adjuvante und neoadjuvante Therapiekonzepte, Immunkombinationstherapien und zielgerichtete Therapien als Monotherapie oder in Kombination mit Immuncheckpoint‐Inhibitoren befinden sich in klinischer Prüfung.

Modern diagnostics and treatment of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with epithelial and neuroendocrine differentiation, the incidence of which has increased substantially during the last decades. Risk factors include advanced age, fair skin type, UV exposure, and immunosuppression. Pathogenetically, a type caused by the Merkel cell polyomavirus is distinguished from a UV-induced type with a high tumor mutational burden. Clinically, MCC presents as a mostly painless, rapidly growing, reddish-violet tumor with a shiny surface, which is preferentially localized in the head-neck region and at the distal extremities. A reliable diagnosis can only be made based on histological and immunohistochemical features. At initial diagnosis, 20-26% of patients show locoregional metastases and 8-14% distant metastases, making staging examinations indispensable. If there is no clinical evidence of metastases, a sentinel lymph node biopsy is recommended. Essential columns of therapy are surgery, adjuvant or palliative radiotherapy and, in advanced inoperable stages, medicamentous tumor therapy. The introduction of immune checkpoint inhibitors has led to a paradigm shift, as they provide a considerably longer duration of response and better survival rates than chemotherapy. The PD-L1 inhibitor avelumab is approved for treatment of metastatic MCC in Germany, but the PD-1 antibodies pembrolizumab and nivolumab are also used with success. Adjuvant and neoadjuvant treatment concepts, immune combination therapies and targeted therapies as monotherapy or in combination with immune checkpoint inhibitors are in the clinical trial phase.

An update on Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare cancer of the skin characterized by a neuroendocrine phenotype and an aggressive clinical behavior. It frequently originates in sun-exposed body areas, and its incidence has steadily increased in the last three decades. Merkel cell polyomavirus (MCPyV) and ultraviolet (UV) radiation exposure are the main causative agents of MCC, and distinct molecular features have been documented in virus-positive and virus-negative malignancies. Surgery remains the cornerstone of treatment for localized tumors, but even when integrated with adjuvant radiotherapy is able to definitively cure only a fraction of MCC patients. While characterized by a high objective response rate, chemotherapy is associated with a short-lasting benefit of approximately 3 months. On the other hand, immune checkpoint inhibitors including avelumab and pembrolizumab have demonstrated durable antitumor activity in patients with stage IV MCC, and investigations on their use in the neoadjuvant or adjuvant setting are currently underway. Addressing the needs of those patients who do not persistently benefit from immunotherapy is currently one of the most compelling unmet needs in the field, and multiple clinical trials of new tyrosine kinase inhibitors (TKIs), peptide receptor radionuclide therapy (PRRT), therapeutic vaccines, immunocytokines as well as innovative forms of adoptive cellular immunotherapies are under clinical scrutiny at present.

Nationwide multidisciplinary consensus on the clinical management of Merkel cell carcinoma: a Delphi panel

Merkel cell carcinoma (MCC) is a rare and highly aggressive cutaneous neuroendocrine carcinoma. The MCC incidence rate has rapidly grown over the last years, with Italy showing the highest increase among European countries. This malignancy has been the focus of active scientific research over the last years, focusing mainly on pathogenesis, new therapeutic trials and diagnosis. A national expert board developed 28 consensus statements that delineated the evolution of disease management and highlighted the paradigm shift towards the use of immunological strategies, which were then presented to a national MCC specialists panel for review. Sixty-five panelists answered both rounds of the questionnaire. The statements were divided into five areas: a high level of agreement was reached in the area of guidelines and multidisciplinary management, even if in real life the multidisciplinary team was not always represented by all the specialists. In the diagnostic pathway area, imaging played a crucial role in diagnosis and initial staging, planning for surgery or radiation therapy, assessment of treatment response and surveillance of recurrence and metastases. Concerning diagnosis, the usefulness of Merkel cell polyomavirus is recognized, but the agreement and consensus regarding the need for cytokeratin evaluation appears greater. Regarding the areas of clinical management and follow-up, patients with MCC require customized treatment. There was a wide dispersion of results and the suggestion to increase awareness about the adjuvant radiation therapy. The panelists unanimously agreed that the information concerning avelumab provided by the JAVELIN Merkel 200 study is adequate and reliable and that the expanded access program data could have concrete clinical implications. An immunocompromised patient with advanced MCC can be treated with immunotherapy after multidisciplinary risk/benefit assessment, as evidenced by real-world analysis and highlighted in the guidelines. A very high consensus regarding the addition of radiotherapy to treat the ongoing focal progression of immunotherapy was observed. This paper emphasizes the importance of collaboration and communication among the interprofessional team members and encourages managing patients with MCC within dedicated multidisciplinary teams. New insights in the treatment of this challenging cancer needs the contribution of many and different experts.

Lymph node ratio predicts efficacy of postoperative radiation therapy in nonmetastatic Merkel cell carcinoma: A population-based analysis

BACKGROUND

After radical resection of a nonmetastatic Merkel cell carcinoma (M0 MCC), postoperative radiation therapy (RT) is recommended as it improves survival. However, the role of RT in specific subgroups of M0 MCC is unclear. We sought to identify whether there is a differential survival benefit from RT in specific M0 MCC patient subgroups.

METHODS

M0 MCC patients from the Surveillance, Epidemiology, and End Results (SEER) database registry were collected. The best prognostic age, tumor size, and lymph node ratio (LNR, ratio between positive lymph nodes and resected lymph nodes) cutoffs were calculated. The primary endpoint was overall survival (OS).

RESULTS

A total of 5644 M0 MCC patients (median age 77 years, 62% male) were included: 4022 (71%) node-negative (N0) and 1551 (28%) node-positive (N+). Overall, 2682 patients (48%) received RT. Age > 76.5 years, tumor size >13.5 mm, and LNR >0.215 were associated with worse OS. RT was associated with longer OS in the M0 MCC, N0, and N+ group and independently associated with a 25%, 27%, and 26% reduction in the risk for death, respectively. RT benefit on survival was increased in tumor size >13.5 mm in the N0 group and LNR >0.215 in the N+ group. No OS benefit from RT was observed in T4 tumors (N0 and N+ groups).

CONCLUSIONS

RT was associated with improved survival in M0 MCC, irrespective of the nodal status. LNR >0.215 is a useful prognostic factor for clinical decision-making and for stratification and interpretation of clinical trials.

Recurrence and Mortality Risk of Merkel Cell Carcinoma by Cancer Stage and Time From Diagnosis

IMPORTANCE

Merkel cell carcinoma (MCC) often behaves aggressively; however, disease-recurrence data are not captured in national databases, and it is unclear what proportion of patients with MCC experience a recurrence (estimates vary from 27%-77%). Stage-specific recurrence data that includes time from diagnosis would provide more precise prognostic information and contribute to risk-appropriate clinical surveillance.

OBJECTIVE

To estimate risk of stage-specific MCC recurrence and mortality over time since diagnosis.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study included 618 patients with MCC who were prospectively enrolled in a Seattle-based data repository between 2003 and 2019. Of these patients, 223 experienced a recurrence of MCC. Data analysis was performed July 2019 to November 2021.

MAIN OUTCOMES AND MEASURES

Stage-specific recurrence and survival, as well as cumulative incidence and Kaplan-Meier analyses.

RESULTS

Among the 618 patients included in the analysis (median [range] age, 69 [11-98] years; 227 [37%] female), the 5-year recurrence rate for MCC was 40%. Risk of recurrence in the first year was high (11% for patients with pathologic stage I, 33% for pathologic stage IIA/IIB, 30% for pathologic stage IIIA, 45% for pathologic stage IIIB, and 58% for pathologic stage IV), with 95% of recurrences occurring within the first 3 years. Median follow-up among living patients was 4.3 years. Beyond stage, 4 factors were associated with increased recurrence risk in univariable analyses: immunosuppression (hazard ratio [HR], 2.4; 95% CI, 1.7-3.3; P < .001), male sex (HR, 1.9; 95% CI, 1.4-2.5; P < .001), known primary lesion among patients with clinically detectable nodal disease (HR, 2.3; 95% CI, 1.4-4.0; P = .001), and older age (HR, 1.1; 95% CI, 1.0-1.3; P = .06 for each 10-year increase). Among 187 deaths in the cohort, 121 (65%) were due to MCC. The MCC-specific survival rate was strongly stage dependent (95% at 5 years for patients with pathologic stage I vs 41% for pathologic stage IV). Among patients presenting with stage I to II MCC, a local recurrence (17 arising within/adjacent to the primary tumor scar) did not appreciably diminish survival compared with patients who had no recurrence (85% vs 88% MCC-specific survival at 5 years).

CONCLUSIONS AND RELEVANCE

In this cohort study, the MCC recurrence rate (approximately 40%) was notably different than that reported for invasive melanoma (approximately 19%), squamous cell carcinoma (approximately 5%-9%), or basal cell carcinoma (approximately 1%-2%) following definitive therapy. Because more than 90% of MCC recurrences arise within 3 years, it is appropriate to adjust surveillance intensity accordingly. Stage- and time-specific recurrence data can assist in appropriately focusing surveillance resources on patients and time intervals in which recurrence risk is highest.

Merkel Cell Carcinoma with Gastric Metastasis, a Rare Presentation: Case Report and Literature Review

INTRODUCTION

Merkel cell carcinoma (MCC) is an infrequent, but highly aggressive neuroendocrine neoplasm of the skin with a propensity for recurrence and metastasis. We report a rare case of gastric metastatic localization of this cancer by focusing on the diagnostic, clinical, and surgical approach to the patient.

CASE REPORT

Clinical presentation begins with a peripheral lymphadenopathy whose immunohistochemical characterization identifies the lymphatic dissemination of the disease. Gradually, the patient develops a severe anaemic state which requires several blood transfusions and surgical gastric resection to remove a large bleeding lesion of the antral region. The histopathological analysis of the specimen confirms the metastatic origin from MCC, but the primitive lesion remains unknown.

DISCUSSION

Since this clinical situation is very rare, we conducted a review of the literature selecting the few cases reported, in order to evaluate the current knowledge on this topic. Metastatic involvement of the stomach from Merkel cell carcinoma is a rare presentation of this disease progression with a frequent delay in formulating the correct diagnosis and in further treatment which may be life-threatening for the patient. As regards the local treatment, there is no specific guideline, and the therapeutic indication should be tailored on the specific case.

Merkel Cell Carcinoma of the Head and Neck: Epidemiology, Pathogenesis, Current State of Treatment and Future Directions

Merkel cell carcinoma (MCC) is a rare, cutaneous neuroendocrine malignancy with increasing incidence. The skin of the head and neck is a common subsite for MCC with distinctions in management from other anatomic areas. Given the rapid pace of developments regarding MCC pathogenesis (Merkel cell polyoma virus (MCPyV)-positive or virus-negative, cell of origin), diagnosis, staging and treatment, and up to date recommendations are critical for optimizing outcomes. This review aims to summarize currently available literature for MCC of the head and neck. The authors reviewed current literature, including international guidelines regarding MCC pathogenesis, epidemiology, diagnosis, staging, and treatment. Subsequently recommendations were derived including the importance of baseline imaging, MCPyV serology testing, primary site surgery, nodal evaluation, radiotherapy, and the increasing role of immune modulating agents in MCC. MCPyV serology testing is increasingly important with potential distinctions in treatment response and surveillance between virus-positive and virus-negative MCC. Surgical management continues to balance optimizing local control with minimal morbidity. Similarly, radiotherapy continues to have importance in the adjuvant, definitive, and palliative setting for MCC of the head and neck. Immunotherapy has changed the paradigm for advanced MCC, with increasing work focusing on optimizing outcomes for non-responders and high-risk patients, including those with immunosuppression.

Case Report: Clinical Experience With Avelumab in Patients With Metastatic Merkel Cell Carcinoma and Brain Metastases Treated in Europe

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer that can metastasize rapidly. In patients with metastatic MCC (mMCC), brain metastases are uncommon but are associated with poor prognosis; furthermore, there is limited published literature regarding treatment of these patients, and no specific regimens are currently recommended by guidelines. Avelumab, an anti-programmed death ligand 1 monoclonal antibody, was the first approved treatment for patients with mMCC. Here, we present 4 cases of patients with mMCC and brain metastases treated with avelumab. Patient age ranged from 48 to 70 years, and all patients received avelumab as second-line therapy following disease progression with platinum-based chemotherapy. Patient cases 1 and 2 received avelumab alone and experienced rapid disease progression according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1). In patient case 3, avelumab alone resulted in a prolonged complete response by RECIST 1.1 of 1 brain metastasis and partial response by RECIST 1.1 of a second brain metastasis. After 11 months of avelumab treatment, the patient received concurrent stereotactic radiosurgery that resulted in complete response of the second metastasis. Patient case 4 achieved a partial response by RECIST 1.1 with avelumab plus stereotactic radiosurgery. These results suggest that avelumab followed by radiotherapy or with concurrent radiotherapy may be an effective treatment option for patients with mMCC and brain metastases.

Merkel Cell Carcinoma of Unknown Primary: Immunohistochemical and Molecular Analyses Reveal Distinct UV-Signature/MCPyV-Negative and High Immunogenicity/MCPyV-Positive Profiles

Simple Summary

Merkel cell carcinomas (MCCs) of unknown primary are defined as deep-seated tumors without an associated cutaneous tumor. Although the distinction has important clinical implications, it remains unclear whether these tumors represent primary tumors of lymph nodes or metastatic cutaneous primaries. We compared the immunohistochemical profiles of four groups of Merkel cell carcinomas (virus-positive and virus-negative unknown primary tumors and virus-positive and virus-negative cutaneous tumors) and performed molecular studies on the unknown primary tumors. Virus-positive and virus-negative Merkel cell carcinomas of unknown primary (MCC-UPs) exhibited an immunoprofile similar to virus-positive and virus-negative primary cutaneous MCCs, respectively. Similar to primary cutaneous Merkel cell carcinomas, virus-negative unknown primary tumors exhibited UV signatures and frequent high tumor mutational burdens, whereas few molecular alterations were noted in virus-positive tumors. Although additional studies are warranted for the virus-positive cases, our findings are supportive of a cutaneous metastatic origin for virus-negative Merkel cell carcinomas of unknown primary.

Abstract

Background: Merkel cell carcinomas of unknown primary (MCC-UPs) are defined as deep-seated tumors without an associated cutaneous tumor. Although the distinction has important clinical implications, it remains unclear whether these tumors represent primary tumors of lymph nodes or metastatic cutaneous primaries. Methods: We compared the immunohistochemical profiles of four groups of MCCs (Merkel cell polyomavirus (MCPyV)-positive UP, MCPyV-negative UP, MCPyV-positive known primary (KP), and MCPyV-negative KP) using B-cell and pre-B-cell markers, cell cycle regulating proteins, follicular stem cell markers, and immune markers, and performed next generation and Sanger sequencing. Results: Virus-positive and virus-negative MCC-UPs exhibited an immunoprofile similar to virus-positive and virus-negative primary cutaneous MCCs, respectively. MCC-UP tumors (both virus-positive and -negative) were immunogenic with similar or even higher tumoral PD-L1 expression and intratumoral CD8 and FoxP3 infiltrates in comparison to MCPyV-positive cutaneous tumors. In addition, similar to primary cutaneous MCCs, MCPyV-negative MCC-UPs exhibited UV signatures and frequent high tumor mutational burdens, whereas few molecular alterations were noted in MCPyV-positive MCC-UPs. Conclusions: Our results showed distinct UV-signatures in MCPyV-negative tumors and high immunogenicity in MCPyV-positive tumors. Although additional studies are warranted for the MCPyV-positive cases, our findings are supportive of a cutaneous metastatic origin for MCPyV-negative MCC-UP tumors.

Surgical Management of Merkel Cell Carcinoma

The incidence of Merkel cell carcinoma (MCC) continues to increase. Understanding of MCC biology has advanced rapidly, with current staging providing valuable prognostic information. MCC treatment often is multidisciplinary. Surgery remains an important component in the staging and treatment, most commonly involving wide excision of the cancer and sentinel lymph node biopsy. Lymphadenectomy is used to treat nodal disease. Radiotherapy enhances locoregional control and possibly survival. Systemic therapies, in particular novel immunotherapies, may be promising in the treatment of advanced or recurrent and metastatic disease.

Pembrolizumab and other immune checkpoint inhibitors in locally advanced or metastatic Merkel Cell Carcinoma: safety and efficacy

INTRODUCTION

Merkel Cell Carcinoma (MCC) is a rare aggressive skin cancer, mostly affecting elderly patients. Until recently, patients with advanced disease were treated with cytotoxic chemotherapies despite rapid chemoresistance and high toxicity. As with other cancers, immune checkpoint inhibitors (CPI), including pembrolizumab, allow durable responses with a manageable safety profile in these patients.

AREAS COVERED

This review describes the rationale for using PD-1/PD-L1 inhibitors in MCC, as well as efficacy and safety results from the three open-label trials investigating pembrolizumab or other PD-1/PD-L1 inhibitors in patients with advanced MCC. Real-life experience and predictive pre-treatment biomarkers are discussed to assess which patients are likely to be candidates for such strategies. Ongoing fields of research include the use of CPI in the adjuvant or neoadjuvant setting and combined strategies in refractory patients. Expert Opinion: CPI have become the standard of care for frontline treatment in patients with advanced MCC. Earlier introduction of CPI in the disease course, including neo-adjuvant and adjuvant settings, is likely to improve the outcomes further. Given the rarity of this cancer, we still need to harmonize efforts in order to conduct large-scale trials and efficiently identify best optimal care.

Non-Melanoma Skin Cancers: Biological and Clinical Features

Non-melanoma skin cancers (NMSCs) include basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and Merkel cell carcinoma (MCC). These neoplasms are highly diverse in their clinical presentation, as well as in their biological evolution. While the deregulation of the Hedgehog pathway is commonly observed in BCC, SCC and MCC are characterized by a strikingly elevated mutational and neoantigen burden. As result of our improved understanding of the biology of non-melanoma skin cancers, innovative treatment options including inhibitors of the Hedgehog pathway and immunotherapeutic agents have been recently investigated against these malignancies, leading to their approval by regulatory authorities. Herein, we review the most relevant biological and clinical features of NMSC, focusing on innovative treatment approaches.

Landscape and Future Perspectives of Immunotherapy in Neuroendocrine Neoplasia

BACKGROUND

Neuroendocrine neoplasms are rare entities consisting of a heterogeneous group of tumors that can originate from neuroendocrine cells present in the whole body. Their different behavior, metastatic potential, and prognosis are highly variable, depending on site of origin, grade of differentiation, and proliferative index. The aim of our work is to summarize the current knowledge of immunotherapy in different neuroendocrine neoplasms and its implication in clinical practice.

RESULTS

Several studies evaluated the efficacy and safety of immunotherapy in neuroendocrine neoplasms, in any setting of treatment, alone or in combination. Studies led to approval in neuroendocrine neoplasia of the lung, in combination with chemotherapy as first-line treatment or as a single-agent in a third-line setting, and Merkel cell carcinoma as a single agent. Results in other settings have been disappointing so far.

CONCLUSIONS

Immunotherapy seems a valid treatment option for high grade, poorly differentiated neoplasms. Future trials should explore the combination of immunotherapy with other agents, such as anti-angiogenic or other immunotherapy agents, in order to evaluate potential efficacy in low and intermediate grades, well differentiated tumors.

Danger is only skin deep: aggressive epidermal carcinomas. An overview of the diagnosis, demographics, molecular-genetics, staging, prognostic biomarkers, and therapeutic advances in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a high grade primary cutaneous neuroendocrine carcinoma and is among the most aggressive cutaneous malignancies. The rising incidence of MCC, together with its often rapidly aggressive course, underscore a critical need to recognize the histopathologic and the immunohistochemical features that inform its accurate diagnosis. In the current review, we summarize the current state of knowledge regarding the accurate diagnosis of MCC and the exclusion of other entities in the differential diagnosis. We provide a comprehensive review of genomic studies that identified the molecular-genetic drivers of MCC as well as a summary of studies identifying prognostic biomarkers that can facilitate risk stratification. Importantly, Merkel cell polyomavirus (MCPyV) appears to be causative in most cases of MCC and represents both a diagnostic and prognostic marker. Finally, as staging of MCC has undergone critical refinements with the introduction of the 8th Edition of the American Joint Committee on Cancer staging system, we provide an update on MCC staging. In particular, the prognostic significance of the sentinel lymph node (SLN) in MCC necessitates a systematic approach to its evaluation and diagnosis to ensure accurate and consistent risk stratification for patients, and we therefore provide a comprehensive overview of SLN evaluation in MCC. Finally, the intimate relationship between MCC and the integrity of the host immune system has led to paradigm-shifting therapeutic advances with the successful application of immune checkpoint blockade to treat patients with advanced disease, and we therefore summarize those studies and the correlative studies in which predictive biomarkers have been identified.

Nodal Merkel Cell Carcinoma in Head and Neck Lesions with an Unknown Primary: A Case Report in Light of the Literature

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine skin cancer. To diagnose nodal MCC with an unknown primary disease is challenging, and it has to be separated from other nodal metastatic neoplasms. We report a unique case of nodal MCC in head and neck lesions with an unknown primary. A 70-year-old woman was admitted to our department with a right submandibular mass. Fine needle aspiration biopsy was performed and indicated malignancy. F-18-fluorodeoxyglucose positron emission tomography (PET) demonstrated abnormal accumulation in the right submandibular lymph node, right palatine tonsil, and right thyroid gland. For diagnostics and treatment, bilateral selective neck lymph node dissection, right tonsillectomy, and right thyroidectomy were performed. Histopathological examination revealed that most parts of the submandibular lymph node were occupied by diffuse sheets of tumor cells. Contrary to our expectation, malignant cells were not detected in the right palatine tonsil and right thyroid. Immunohistochemistry demonstrated a marked positive reaction for AE1/AE3, chromogranin A, synaptophysin, cytokeratin 20 (CK20) and CD56 and a negative reaction for vimentin, leucocyte common antigen (LCA), thyroid transcription factor-1 (TTF1) and cytokeratin 7 (CK7) in the tumor cells. Immunostaining of Merkel cell polyomavirus-large T antigen (MCPyV-LT) showed a positive reaction and MCPyV-positive MCCs were assessed by PCR analysis, demonstrating that viral copy number was 12.8 copies per cell. These histological findings confirmed the diagnosis of Merkel cell carcinoma of the lymph node. In cases of tumors in the lymph node with a neuroendocrine appearance in head and neck lesions, it is necessary to eliminate the possibility of metastasis from MCC.

Merkel cell carcinoma in Taiwan: A series of 24 cases and literature review

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine carcinoma of the skin. The available reports of MCC in Asia are limited; in this study, we report the largest series of MCC in Taiwan to date.The series is composed by 24 pathologically proven MCC cases, which were retrospectively reviewed in Chang Gung Memorial Hospital in Taiwan between 2000 and 2018.The tumor occurred predominantly in men (80%) and in the elderly (median 74.8 years). Twenty-one patients had locoregional MCC and 3 had metastatic MCC at the time of diagnosis. Patients with pathologically proven negative nodes by sentinel lymph node biopsy (SLNB) showed better survival time than those without SLNB in 16 clinically node-negative MCC cases undergoing primary surgery. Salvage surgery for loco-regional recurrence lengthened the survival time and possibly cured recurrent MCC. Palliative chemotherapy with cisplatin and etoposide showed a response rate of 25%, progression-free survival of 3.6 months, and overall survival of 14.8 months in 4 metastatic/recurrent MCC. Avelumab treatment was effective in 1 patient, who achieved a durable disease control.This observational cohort of MCC patients in Taiwan suggests aggressive surgical intervention including wide excision and lymph node management, salvage operation is critical for early MCC patients, and palliative chemotherapy and immunotherapy showed their efficacy for advanced MCC patients.

Seed and soil? - Pharyngeal Merkel cell carcinoma after radiotherapy for laryngeal squamous cell carcinoma

Merkel cell carcinoma (MCC) is a neuroendocrine cutaneous malignancy that may present as metastatic disease without a known primary site but, most commonly originates in the sun-exposed skin of the head, neck, and extremities. We present a 66-year-old male treated with chemo-radiation for T3N2cM0 laryngeal squamous cell carcinoma (SCCa) six years before he was diagnosed with MCC isolated to the radiated laryngopharynx. Mucosal MCC is rare and radiation-induced MCC has been hypothesized to occur in previously radiated tissue but, never before to the laryngopharynx. Implications regarding cancer biology and management is focused with discussion on relevant advances in pathologic assessment and immunotherapy.

Unknown primary Merkel cell carcinoma with cutaneous spread

The authors present the case of a woman in the seventh decade of life with medical history of: left nephrectomy for renal tuberculosis and non-Hodgkin's lymphoma treated with chemotherapy (QT) and radiotherapy. She presented with a 2-month history of non-tender, left inguinal lymph node enlargement. Positron Emission Tomography (PET)-CT -scanshowed hypermetabolic inguinal and retroperitoneal lymphadenopathies, no primary tumour. On the second dermatological examination a pink, 2 cm plaque on the anterior left knee was noted. The histopathological analysis revealed Merkel cell carcinoma. The patient underwent two lines of systemic QT, with life-threatening toxicities limiting treatment. Followed overwhelming disease progression with lymphoedema and numerous skin metastases in the left lower limb. The patient received palliative care until death. The rare incidence of such neoplasia and its uncommon clinical presentation justifies reporting this case and highlights the importance of multidisciplinary teams in the management of cancer patients.

Differential Outcomes Among Immunosuppressed Patients With Merkel Cell Carcinoma: Impact of Immunosuppression Type on Cancer-specific and Overall Survival

OBJECTIVES

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer with higher incidence among whites, elderly, and immunosuppressed patients. Although immunosuppressed MCC patients are at higher risk of recurrence and MCC-related death, it is unknown whether immunosuppression type is associated with differential outcomes.

MATERIALS AND METHODS

We retrospectively evaluated 89 nonmetastatic MCC patients with a diagnosis of chronic immunosuppression. Immunosuppression was categorized as chronic lymphocytic leukemia (31% of cohort), other hematologic malignancies (18%), solid organ transplant (21%), autoimmune disease (21%), and human immunodeficiency virus acquired deficiency syndrome (8%). Progression-free survival (PFS) and MCC-specific survival (MSS) were estimated with the cumulative incidence function. Overall survival (OS) was estimated by the Kaplan-Meier method.

RESULTS

With a median follow-up of 52 months, 53 deaths occurred (42 from MCC, 7 unknown, and 4 non-MCC). Two-year PFS, MSS, and OS were 30%, 55%, and 52%, respectively. Human immunodeficiency virus/acquired deficiency syndrome and solid organ transplant patients were diagnosed with MCC at a younger age (median 55 and 59 y, respectively) and with more advanced stage disease compared with other immunosuppressed subgroups. PFS did not significantly differ among the 5 immunosuppression subgroups (P=0.30), but significant differences were observed in MSS and OS (both P=0.01). Controlling for potential confounders for OS, including age and stage, immunosuppression type was still significantly associated with risk of death (P=0.01).

CONCLUSIONS

Among immunosuppressed MCC patients, recurrent MCC is the major cause of mortality. The risk of death from MCC differs among immunosuppression types, suggesting important biological differences in host-tumor immune interactions.

Effect of Patient Immune Status on the Efficacy of Radiation Therapy and Recurrence-Free Survival Among 805 Patients With Merkel Cell Carcinoma

PURPOSE

Patients with Merkel cell carcinoma (MCC) with chronic immunosuppression (IS) have worse outcomes, but the mechanisms are not well understood. We hypothesized that these differences may be mediated in part by differential response to treatment, and we evaluated whether radiation therapy (RT) efficacy is altered among IS compared with immune-competent (IC) patients with MCC.

METHODS AND MATERIALS

Among 805 patients with MCC, recurrence-free survival (RFS) and patterns of first recurrence were compared between 89 IS and 716 IC patients with stage I to III MCC treated with curative intent. We used a Fine and Gray's competing risk multivariable analysis to estimate associations with RFS.

RESULTS

IS and IC patients with MCC had similar demographic and disease characteristics. Most (77% IC, 86% IS) were irradiated (median, 50.4 Gy IC, 50.3 Gy IS), although more IS patients were irradiated to the primary site (97% vs 81%). With a median follow-up of 54.4 months, IS patients had inferior RFS (2-year: 30% vs 57%; P < .0001) and higher rates of local recurrence as the first site of relapse (25% vs 12%; P = .0002). The association between RT and RFS differed by immune status (interaction P = .01). Although RT was associated with significantly improved RFS among IC patients (hazard ratio 0.56, 95% confidence interval 0.44-0.72), no difference in RFS was observed with RT among IS patients (hazard ratio 1.49, 95% confidence interval 0.70-3.17).

CONCLUSIONS

Radiation therapy efficacy at current standard RT doses for MCC is impaired among immunosuppressed patients with MCC. Although a strong link between durability of RT response and immune function does not appear to be evident in most cancers, our results may reflect an especially dynamic interaction between immune status and RT efficacy in MCC.

Immunotherapy for Merkel cell carcinoma: a turning point in patient care

Merkel Cell carcinoma (MCC) is a rare but aggressive cancer, with an estimated disease-associated mortality as high as 46%. MCC has proven to be an immunologically responsive disease and the advent of immune checkpoint inhibitors has changed the treatment landscape for patients with advanced MCC. In this review, we discuss the rationale for the use of immune checkpoint inhibition, review current single agent therapies tested in and approved for MCC, and discuss emerging immunotherapeutic options for these patients.

Proceedings of the NASHNP Companion Meeting, March 18th, 2018, Vancouver, BC, Canada: Salivary Neuroendocrine Carcinoma-An Overview of a Rare Disease with an Emphasis on Determining Tumor Origin

Salivary neuroendocrine carcinomas are rare and the overwhelming majority is high-grade. The parotid gland is the most commonly involved site followed by the submandibular gland. Most arise de novo but rare examples occurring as a high-grade transformation of another type of salivary gland neoplasm exist. There is significant morphologic and immunophenotypic overlap with neuroendocrine carcinomas of other sites, especially the skin. Like cutaneous neuroendocrine (or Merkel cell) carcinomas, approximately three-fourths are cytokeratin 20 positive. Cytokeratin 20 positive salivary neuroendocrine carcinomas are often referred to as being of the 'Merkel cell type' since most other non-cutaneous neuroendocrine carcinomas are cytokeratin 20 negative. Salivary neuroendocrine carcinomas may be challenging to separate from Merkel cell carcinomas of the head and neck on pathologic grounds because the latter often metastasize to the parotid gland. Clinical history is often relied upon to separate primary salivary tumors from cutaneous metastases but may not be helpful in all cases. Here we review the clinical, pathologic and molecular features of salivary neuroendocrine carcinomas focusing on high-grade major salivary gland tumors. The difficulty in separating salivary tumors from metastatic Merkel cell carcinoma will be highlighted.

Update on Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma. Incidence of MCC continues to rise, and risk factors include advanced age, pale skin, chronic sun exposure, and immune suppression. Diagnosing MCC utilizes a combination of morphology and immunohistochemistry. Merkel cell polyomavirus (MCPyV) is present in approximately 70-80% of MCCs and represents a key pathogenic driver in those MCCs. In contrast, MCPyV-negative MCCs arise through progressive accumulation of ultraviolet-light induced somatic mutations. Staging of MCC proceeds according to the American Joint Commission on Cancer (AJCC) 8th Edition, which utilizes features of the primary tumor together with regional lymph node(s) (clinically and/or pathologically detected) and/or distant metastases. Many potentially useful biomarkers have been studied to refine risk stratification in MCC. In recent years, the host immune infiltrate has been leveraged as immune checkpoint blockade has emerged as an efficacious mode of treatment for patients with advanced MCC.

Merkel Cell Carcinoma: An Update and Immunotherapy

Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer with frequent metastasis and death. MCC has a mortality rate of 30%, making it more lethal than malignant melanoma, and incidence of MCC has increased almost fourfold over the past 20 years in the USA. MCC has long been considered to be an immunogenic cancer because it occurs more frequently in immunosuppressed patients from organ transplant and HIV infection than in those with immunocompetent. Chronic UV light exposure and clonal integration of Merkel cell polyomavirus (MCPyV) are two major causative factors of MCC. Approximately 80% of MCC are associated with MCPyV, and T cells specific for MCPyV oncoproteins are present in the blood and tumors of patients. Several studies have shown that a subset of MCCs express PD-1 on tumor-infiltrating lymphocytes and express PD-L1 on tumor cells, which suggests an endogenous tumor-reactive immune response that might be unleashed by anti-PD-1 or anti-PD-L1 drugs.

Merkel Cell Carcinoma Patients Presenting Without a Primary Lesion Have Elevated Markers of Immunity, Higher Tumor Mutation Burden, and Improved Survival

Purpose: Patients presenting with nodal Merkel cell carcinoma without an identifiable (unknown) primary lesion (MCC-UP) are nearly twice as likely to survive compared with similarly staged patients with known primary lesions (MCC-KP). The basis of this previously reported finding is unclear.Experimental Design: Survival analyses and markers of immunity were evaluated in 123 patients with advanced MCC. Whole-exome sequence data were analyzed from 16 tumors.Results: As in prior studies, patients with nodal MCC-UP had strikingly improved MCC-specific survival as compared with MCC-KP patients (HR, 0.297; P < 0.001). Surprisingly, patients presenting with distant metastatic MCC-UP also had significantly improved survival (HR, 0.296; P = 0.038). None of the 72 patients with MCC-UP were immunosuppressed as compared to 12 of the 51 (24%) patients with MCC-KP (P < 0.001). Merkel polyomavirus oncoprotein antibody median titer was higher in MCC-UP patients (26,229) than MCC-KP patients (3,492; P < 0.001). In addition, the median number of nonsynonymous exome mutations in MCC-UP tumors (688 mutations) was markedly higher than MCC-KP tumors (10 mutations, P = 0.016).Conclusions: This is the first study to our knowledge to explore potential underlying immune-mediated mechanisms of MCC-UP presentation. In this cohort, MCC-UP patients were never immune suppressed, had higher oncoprotein antibody titers, and higher tumor mutational burdens. In addition, we show that nodal tumors identified in MCC-UP patients did indeed arise from primary skin lesions as they contained abundant UV-signature mutations. These findings suggest that stronger underlying immunity against MCC contributes to primary lesion elimination and improved survival. Clin Cancer Res; 24(4); 963-71. ©2017 AACR.

Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare but highly aggressive skin cancer with neuroendocrine features. MCC pathogenesis is associated with either the presence of Merkel cell polyomavirus or chronic exposure to ultraviolet light (UV), which can cause a characteristic pattern of multiple DNA mutations. Notably, in the Northern hemisphere, the majority of MCC cases are of viral aetiology; by contrast, in areas with high UV exposure, UV-mediated carcinogenesis is predominant. The two aetiologies share similar clinical, histopathological and prognostic characteristics. MCC presents with a solitary cutaneous or subcutaneous nodule, most frequently in sun-exposed areas. In fact, UV exposure is probably involved in both viral-mediated and non-viral-mediated carcinogenesis, by contributing to immunosuppression or DNA damage, respectively. Confirmation of diagnosis relies on analyses of histological features and immunological marker expression profiles of the lesion. At primary diagnosis, loco-regional metastases are already present in ∼30% of patients. Excision of the tumour is the first-line therapy; if not feasible, radiotherapy can often effectively control the disease. Chemotherapy was the only alternative in advanced-stage or refractory MCC until several clinical trials demonstrated the efficacy of immune-checkpoint inhibitors.

Immune evasion mechanisms and immune checkpoint inhibition in advanced merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare skin cancer caused by Merkel cell polyomavirus (MCPyV) infection and/or ultraviolet radiation-induced somatic mutations. The presence of tumor-infiltrating lymphocytes is evidence that an active immune response to MCPyV and tumor-associated neoantigens occurs in some patients. However, inhibitory immune molecules, including programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1), within the MCC tumor microenvironment aid in tumor evasion of T-cell-mediated clearance. Unlike chemotherapy, treatment with anti-PD-L1 (avelumab) or anti-PD-1 (pembrolizumab) antibodies leads to durable responses in MCC, in both virus-positive and virus-negative tumors. As many tumors are established through the evasion of infiltrating immune-cell clearance, the lessons learned in MCC may be broadly relevant to many cancers.

Merkel cell carcinoma: Epidemiology, prognosis, therapy and unmet medical needs

Merkel cell carcinoma (MCC) is a rare skin cancer that is associated with Merkel cell polyomavirus infection in most cases. Incidence rates of MCC have increased in past decades. Risk factors for MCC include ultraviolet light exposure, immunosuppression and advanced age. MCC is an aggressive malignancy with frequent recurrences and a high mortality rate, although patient outcomes are generally more favourable if the patient is referred for treatment at an early stage. Although advances have been made recently in the MCC field, large gaps remain with regard to definitive biomarkers and prognostic indicators. Although MCC is chemosensitive, responses in advanced stages are mostly of short duration, and the associated clinical benefit on overall survival is unclear. Recent nonrandomised phase 2 clinical trials with anti-PD-L1/PD-1 antibodies have demonstrated safety and efficacy; however, there are still no approved treatments for patients with metastatic MCC. Patients with advanced disease are encouraged to participate in clinical trials for treatment, indicating the largely unmet need for durable, safe treatment within this population.

Analysis of Prognostic Factors from 9387 Merkel Cell Carcinoma Cases Forms the Basis for the New 8th Edition AJCC Staging System

BACKGROUND

The first consensus Merkel cell carcinoma (MCC) staging system was published in 2010. New information on the clinical course prompts review of MCC staging.

METHODS

A total of 9387 MCC cases from the National Cancer Data Base Participant User File with follow-up and staging data (1998-2012) were analyzed. Prognostic differences based on clinical and pathological staging were evaluated. Survival estimates were compared by disease extent.

RESULTS

Sixty-five percent of cases presented with local disease, whereas 26 and 8 % presented with nodal and distant disease. Disease extent at presentation was predictive of 5-year overall survival (OS) with estimates of 51, 35, and 14 % for local, nodal, and distant disease. Tumor burden at the regional nodal basin was predictive of 5-year OS with estimates of 40 and 27 % for clinically occult and clinically detected nodal disease. For local disease, we confirm improved prognosis when the regional nodal basin was negative by pathological compared with clinical staging. We identified 336 cases with clinically detected nodal disease and unknown primary tumor and showed improved prognosis over cases presenting with concurrent primary tumor (OS estimates of 42 vs. 27 %).

CONCLUSIONS

Analysis of a national dataset of MCC cases validates the predictive value of disease extent at presentation. Separation of clinical and pathological stage groups and regrouping of unknown primary tumors are supported by the analysis. The revised staging system provides more accurate prognostication and has been formally accepted by the AJCC staging committee for inclusion in the 8th edition.

Lymph node location of a clear cell hidradenoma: report of a patient and review of literature

Cutaneous clear cell hidradenoma is an uncommon benign adnexal tumor which is not supposed to metastasize, contrary to its rare malignant counterpart, hidradenocarcinoma. We report the case of a 49-year-old man, who had had a stable inguinal lymph node enlargement for 6 years. An excision was performed and revealed an intra-nodal tumor, made of large clear cells with abundant cytoplasm and round nuclei without atypia or mitosis. The immunohistochemical staining showed diffuse positivity for keratin AE1/AE3, keratin 5/6 and p63, and focal staining with keratin 7, epithelial membrane antigen (EMA) and carcinous epithelial antigen (CEA), which underlined some ductular structures. Tumor cells were negative for renal markers PAX8 and CD10. Ki67 stained less than 1% of tumor cells. A translocation involving MAML2 gene was evidenced by fluorescence in situ hybridization (FISH) analysis. No primary cutaneous tumor was found after extensive examination. Altogether, these results are in favor of an isolated nodal hidradenoma, for which we discuss two hypothesis: a primary nodal lesion, or a 'benign metastasis' of a cutaneous tumor. Cases of morphologically benign hidradenoma with lymph node involvement are exceptional. Our case, similar to every other reported case, was associated with an excellent prognosis, supporting the idea that these patients should not be overtreated.

Merkel Cell Carcinoma: When Does Size Matter for Radiotherapy?

Merkel cell carcinoma is a very aggressive, rare cancer of the skin. It has a high propensity for local, regional, and distant recurrence and has recently been associated with a viral etiology from the recently diagnosed Merkel Cell Polyoma Virus. The optimal management remains controversial. We discuss the case of a man with a 26 cm axillary lymph node metastasis of unknown primary treated with radiotherapy.

Merkel cell carcinoma of unknown primary site; case presentation and review of the literature

Merkel cell carcinoma (MCC) is a rare skin malignancy associated with sun exposure and considered as a Neuroendocrine Tumor due to its characteristic histologic features. However there is increasing number of reports of Unknown Primary MCC's (UPMCC). Although initially UPMCC was considered a variant of known primary MCC, there is growing evidence that it could represent a different clinical entity.

We present the case of a 60 year-old male patient who was referred to our department for surgical management of lymph node disease for UPMCC. The patient had undergone excisional biopsy of an inguinal lump, which was found to be an infiltrated lymph node by MCC. The patient underwent full imaging staging including a PET/CT, which failed to identify a primary site, and revealed only intra-abdominal lymph node disease. The patient underwent extended retroperitoneal and inguinal lymph node dissection and remains free of recurrence 16 months postoperatively.

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Unknown Primary Merkel cell carcinoma is a rare NET, which usually presents with extensive lymph node involvement.

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This tumor follows a more indolent natural course than a Merkel cell carcinoma of known primary and of similar staging.

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Surgical excision with R0 resection remains a common practice in the management of unknown primary Merkel cell carcinoma.

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Adjuvant chemotherapy after R0 resection is the usual practice, despite the lack of good quality literature evidence.

Neuroendocrine Merkel cell nodal carcinoma of unknown primary site: management and outcomes of a rare entity

Merkel cell nodal carcinoma of unknown primary (MCCUP) is a rare neuroendocrine tumour with distinct clinical and biological behaviour. We conducted a review of retrospective data extracted from 90 patients focusing on the management and outcome of this disease. We also compared life expectancy of these patients with the outcome of patients with known Merkel primaries and with neuroendocrine cancers of unidentifiable primary. There is a limited body of data for this type of malignancy, however, patients with Merkel cell nodal carcinoma of unknown primary site, seem to have better survival when treated aggressively than patients with cutaneous Merkel tumours of the same stage and equal survival with patients with low-grade neuroendocrine tumour of unknown origin. The lack of prospective trials, and the inadequate data, hamper the management of these tumours. Establishment of treatment guidelines is urgently needed.

Milestones in the staging, classification, and biology of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive skin cancer that is causally associated with ultraviolet light exposure and a recently discovered polyomavirus. Before 2010, MCC was staged using any of 5 unique systems in active use. In 2010, a consensus staging system for MCC was adopted worldwide and replaced these systems. This consensus system includes substages that reflect prognostic differences based on whether nodal evaluation was performed by pathologic analysis or clinical assessment alone. MCC-specific disease classification in ICD-9, to be expanded in the upcoming ICD-10, has improved the ability to track and manage this malignancy. Several biomarkers and histopathologic features have been identified that improve understanding of this cancer and may lead to future refinement of the current staging system. In 2008, the Merkel cell polyomavirus was discovered and is now thought to be a critical mechanism of transformation in at least 80% of MCCs. In patients who produce antibodies to the viral T-antigen oncoprotein, the titer increases and decreases with MCC disease burden and can be a clinically useful marker of recurrence. Diverse studies link CD8-positive T-cell function with outcomes in MCC and serve as the rational basis for ongoing trials of therapies to augment cellular immunity. This article reviews basic and translational research insights that will lead to improved staging, prognostic accuracy, and mechanism-based therapy for this often-lethal skin cancer.

Merkel cell carcinoma - recent advances in the biology, diagnostics and treatment

Merkel cell carcinoma (MCC) is an uncommon primary cutaneous carcinoma with neuroendocrine differentiation. Since recent discovery of MCCs strong association with Merkel cell polyomavirus (MCPyV), there has been a rapid increase in the understanding of the carcinomas genetics, molecular biology and pathogenesis. In our study, we reviewed recent advances and controversies concerning MCC histogenesis, epidemiology, diagnostic and prognostic markers. We analyzed the association of MCPyV with MCC and the possible new targets for therapy. We also examined English-based literature regarding MCC pathogenesis published between 2008 and 2013, which lead to a deeper understanding of the topic. Our study showed that the association of MCPyV strongly influences the course of MCC. Additionally, it has been shown that a immunological response to MCPyV may in the future give hope to identify new therapeutic strategies in treatment of this fatal malignancy. This article is part of a Directed Issue entitled: Rare Cancers.