Increasing tumor thickness is associated with recurrence and poorer survival in patients with Merkel cell carcinoma

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.

Tumor thickness in mesothelioma predicts differential response to neoadjuvant therapy and survival

OBJECTIVE

Neoadjuvant systemic therapy in resectable malignant pleural mesothelioma remains controversial and demonstrates variable responses. We sought to evaluate tumor thickness as a predictor of response to neoadjuvant therapy and as a prognostic marker for overall survival.

METHODS

Data from patients who underwent neoadjuvant therapy followed by cytoreductive surgery from 2002 to 2019 were reviewed. Baseline and postneoadjuvant therapy tumor thickness were measured on computed tomography. Radiological tumor response was categorized as progressive disease (≥20% increase), partial response (≥30% decrease), or stable disease (in between). Tumor response outcomes were modeled using logistic regression and multinomial regression models. Overall survival was evaluated based on tumor thickness and tumor response.

RESULTS

Of the 143 patients reviewed, 36 (25%) had progressive disease, 54 (38%) had stable disease, and 56 (39%) had partial response. The baseline tumor thickness of the progressive disease group (36 mm) was lower than in both stable disease and partial response groups (both 63 mm; P < .001). Both logistic regression and multinomial regression analyses demonstrated that thicker baseline tumor thickness was associated with decreased probability of progressive disease and increased probability of partial response. In a multivariable Cox model, thicker postneoadjuvant therapy tumor thickness was associated with worse overall survival (hazard ratio, 1.01, 95% confidence interval, 1.00-1.01, P = .008). The same trend was observed for thicker baseline tumor thickness (hazard ratio, 1.02, 95% confidence interval, 1.01-1.04, P = .008), and the risk was decreased in tumors with partial response (hazard ratio, 0.98, 95% confidence interval, 0.96-0.100, P = .014).

CONCLUSIONS

We present the first study demonstrating the relationship between baseline tumor thickness and differential radiographic response to neoadjuvant therapy and survival. Further studies are needed to validate tumor thickness as both a prognostic and predictive biomarker.

[Merkel Cell Carcinoma]

Merkel cell carcinoma represents a neuroendocrine tumour which can grow rapidly and metastasizes early. The median age of patients is 75-80 years. Given the continuously rising population age Merkel cell carcinoma is diagnosed more often. Besides surgery, radiotherapy and chemotherapy immunooncology plays an important role in the treatment of this aggressive tumour.

Postoperative Radiotherapy and the Role of Regional Lymph Node Irradiation in Localized Merkel Cell Carcinoma: A Single-Center Retrospective Analysis

The aim of this study was to analyze the pattern of relapse of patients with Merkel cell carcinoma (MCC) that underwent resection of the primary tumor site and postoperative radiotherapy at the Department of Radiation Oncology of Heidelberg University and to determine the role of the elective radiotherapy of regional lymph nodes with respect to SLNB results. A total of 57 patients were included in the present retrospective analysis. A total of 33 patients had additional lymph node irradiation (LNI); 24 had postoperative radiotherapy of the tumor bed only. Median follow-up was 43 months. Recurrence rate of the total cohort was 22.8%. Most relapses (69%) occurred in the regional nodes. Cumulative infield-tumor recurrence rate was low with 5.3%. Regional recurrence was more frequent in the cohort without LNI with 85.7% versus 37.5% with LNI. These results were similar for patients with negative sentinel lymph node (SLN) only with 80% regional relapses for those without LNI versus 33% with LNI. In conclusion, our data show that regional recurrence is the most frequent site of relapse in stage I-III MCC treated with curative intended postoperative radiotherapy and that elective irradiation of the regional lymph nodes reduces the risk of regional relapse even if the SLN was negative.

An Internally Validated Prognostic Risk-Score Model for Disease-Specific Survival in Clinical Stage I and II Merkel Cell Carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy for which factors predictive of disease-specific survival (DSS) are poorly defined.

METHODS

Patients from six centers (2005-2020) with clinical stage I-II MCC who underwent sentinel lymph node (SLN) biopsy were included. Factors associated with DSS were identified using competing-risks regression analysis. Risk-score modeling was established using competing-risks regression on a training dataset and internally validated by point assignment to variables.

RESULTS

Of 604 patients, 474 (78.5%) and 128 (21.2%) patients had clinical stage I and II disease, respectively, and 189 (31.3%) had SLN metastases. The 5-year DSS rate was 81.8% with a median follow-up of 31 months. Prognostic factors associated with worse DSS included increasing age (hazard ratio [HR] 1.03, p = 0.046), male sex (HR 3.21, p = 0.021), immune compromise (HR 2.46, p = 0.013), presence of microsatellites (HR 2.65, p = 0.041), and regional nodal involvement (1 node: HR 2.48, p = 0.039; ≥2 nodes: HR 2.95, p = 0.026). An internally validated, risk-score model incorporating all of these factors was developed with good performance (AUC 0.738). Patients with ≤ 4.00 and > 4.00 points had 5-year DSS rates of 89.4% and 67.2%, respectively. Five-year DSS for pathologic stage I/II patients with > 4.00 points (n = 49) was 79.8% and for pathologic stage III patients with ≤ 4.00 points (n = 62) was 90.3%.

CONCLUSIONS

A risk-score model, including patient and tumor factors, based on DSS improves prognostic assessment of patients with clinically localized MCC. This may inform surveillance strategies and patient selection for adjuvant therapy trials.

Diagnosis and treatment of Merkel cell carcinoma: European consensus-based interdisciplinary guideline - Update 2022

Merkel cell carcinoma (MCC) is a rare skin cancer, accounting for less than 1% of all cutaneous malignancies. It is found predominantly in white populations and risk factors include advanced age, ultraviolet exposure, male sex, immunosuppression, such as AIDS/HIV infection, haematological malignancies or solid organ transplantation, and Merkel cell polyomavirus infection. MCC is an aggressive tumour with 26% of cases presenting lymph node involvement at diagnosis and 8% with distant metastases. Five-year overall survival rates range between 48% and 63%. Two subsets of MCC have been characterised with distinct molecular pathogenetic pathways: ultraviolet-induced MCC versus virus-positive MCC, which carries a better prognosis. In both subtypes, there are alterations in the retinoblastoma protein and p53 gene structure and function. MCC typically manifests as a red nodule or plaque with fast growth, most commonly on sun exposed areas. Histopathology (small-cell neuroendocrine appearance) and immunohistochemistry (CK20 positivity and TTF-1 negativity) confirm the diagnosis. The current staging systems are the American Joint Committee on Cancer/Union for international Cancer control 8th edition. Baseline whole body imaging is encouraged to rule out regional and distant metastasis. For localised MCC, first-line treatment is surgical excision with postoperative margin assessment followed by adjuvant radiation therapy (RT). Sentinel lymph node biopsy is recommended in all patients with MCC without clinically detectable lymph nodes or distant metastasis. Adjuvant RT alone, eventually combined with complete lymph nodes dissection is proposed in case of micrometastatic nodal involvement. In case of macroscopic nodal involvement, the standard of care is complete lymph nodes dissection potentially followed by post-operative RT. Immunotherapy with anti-PD-(L)1 antibodies should be offered as first-line systemic treatment in advanced MCC. Chemotherapy can be used when patients fail to respond or are intolerant for anti-PD-(L)1 immunotherapy or clinical trials.

Clinical-Pathological Evaluation and Prognostic Analysis of 228 Merkel Cell Carcinomas Focusing on Tumor-Infiltrating Lymphocytes, MCPYV Infection and ALK Expression

Merkel cell carcinoma is a rare and aggressive primary neuroendocrine carcinoma of the skin, whose pathogenesis can be traced back to UV radiation damage or Merkel cell polyomavirus (MCPyV) infection. Despite some improvements on the characterization of the disease partly due to its increased incidence, crucial pathogenetic and prognostic factors still need to be refined. A consecutive series of 228 MCC from three hospitals in Turin was collected with the aim of both analyzing the apparent increase in MCC incidence in our area and investigating the distribution and prognostic role of clinical-pathological parameters, with a focus on MCPyV status, ALK tumor expression and tumor infiltrating lymphocytes (TILs). Review of morphology and conventional immunohistochemical staining was possible in 191 cases. In 50 cases, the expression of the novel neuroendocrine marker INSM1 was additionally assessed. Fourteen cases of MCC of unknown primary skin lesion were identified and separately analyzed. While confirming an exponential trend in MCC incidence in the last decades and providing a description of histological and cytological features of a large series of MCC, the present study concludes that 1) INSM1 is a highly sensitive marker in both skin and lymph node primary MCC; 2) positive MCPyV status, brisk TILs and lower tumor size and thickness are independent positive prognostic parameters, and the combination of the former two may provide a novel tool for prognostic stratification; 3) ALK is expressed 87% of MCC and associated with positive viral status, and could represent a prognostic biomarker, if validated in larger series.

Survival outcomes and epidemiology of Merkel cell carcinoma of the lower limb and hip: A Surveillance, Epidemiology, and End Results analysis 2000-2018

Background

Merkel cell carcinoma of lower limb and hip skin is a rare skin tumor that has a high recurrence rate.

Objective

To assess epidemiology and survival outcomes of the lower limb and hip Merkel cell carcinoma, which are less addressed in the literature.

Methods

The Surveillance, Epidemiology, and End Results database was searched for all cases of skin Merkel cell carcinoma between 2000 and 2018. Demographic and clinicopathologic features were compared between lower limb and other skin localizations using the t test or χ² test. The overall survival (OS) of lower limb Merkel cell carcinoma was calculated using the Kaplan-Meier method. Subgroups were compared using the log rank test. Multivariate cox regression was used to identify independent prognostic factors.

Results

In total, 976 patients were identified. The mean age was 72.7 years. The median OS was 68 months, better than that of other localizations. Older age, regional lymph node, and distant metastasis were associated with low OS. Surgery with >1-cm margins, when associated with radiotherapy, had the best OS. Age, tumor size, lymph node status, presence of metastasis, and treatment sequence were identified as independent prognostic factors.

Conclusion

Lower limb and hip Merkel cell carcinomas have better OS than tumors in other skin localizations. In this dataset, the best OS was ensured using surgery with >1-cm margins and adjuvant radiotherapy.

Merkelzellkarzinom

Das Merkelzellkarzinom ist ein aggressiver neuroendokriner Tumor, welcher durch schnelles Wachstum und frühzeitige Metastasierung charakterisiert ist. Das mediane Erkrankungsalter liegt zwischen 75–80 Jahren. Mit Zunahme des durchschnittlichen Bevölkerungsalters tritt der einstmals seltene Tumor immer häufiger auf. Neben den klassischen Therapiesäulen Chirurgie, Strahlentherapie und Chemotherapie spielt die Immunonkologie auch beim Merkelzellkarzinom eine zunehmend wichtige Rolle.

Relationship between p63 and p53 expression in Merkel cell carcinoma and corresponding abnormalities in TP63 and TP53: a study and a proposal

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous neuroendocrine carcinoma. Oncogenesis occurs via Merkel cell polyomavirus-mediated (MCPyV+) and/or ultraviolet radiation-associated (MCPyV-) pathways. Advanced clinical stage and an MCPyV- status are important adverse prognostic indicators. There is mounting evidence that p63 expression is a negative prognostic indicator in MCC and that it correlates with MCPyV- status. p63 is a member of the p53 family of proteins among which complex interactions occur. It has two main isoforms (proapoptotic TAp63 and oncogenic ΔNp63). Paradoxically, TAp63 predominates in MCC. To explore this quandary, we examined relationships between p63 and p53 expression and corresponding abnormalities in the TP63 and TP53 genes in MCC. A cohort of 26 MCCs (12 MCPyV+ and 14 MCPyV-) was studied. Comparative immunohistochemical expression of p63 and p53 was evaluated semiquantitatively (H scores) and qualitatively (aberrant patterns). The results were compared with genetic abnormalities in TP63 and TP53 via next-generation sequencing. p63 was positive in 73% of cases. p53 showed "wild-type" expression in 69%, with "aberrant" staining in 31%. TP63 mutations (predominantly low-level copy gains; 23% of cases) and mainly pathogenic mutations in TP53 (50% of cases) featured in the MCPyV- subset of cases. p63 expression correlated quantitatively with p53 expression and qualitatively with aberrant patterns of the latter. Increased expression of p63 and p53 and aberrant p53 staining correlated best with TP53 mutation. We propose that p63 expression (ie, proapoptotic TAp63) in MCC is most likely functionally driven as a compensatory response to defective p53 tumor suppressor activity.

Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and extremely aggressive neuroendocrine carcinoma of the skin, with increasing incidence worldwide. This review intends to propose a comprehensive evaluation of MCC epidemiology, clinical features, pathogenetic mechanisms, diagnosis, and therapies. A section is dedicated to immunological aspects and another to the involvement of angiogenesis and angiogenic growth factors in MCC progression, proposing novel diagnostic and therapeutic approaches. Advanced MCC tumors have been treated with immune checkpoint inhibitors with effective results. Therefore, the state of art of this immunotherapy is also examined, reporting on the most recent clinical trials in the field. We conclude by underlining the achievements in the understanding of MCC pathology and indicating the present needs for effective diagnosis and therapeutic management of the disease.

Merkel cell carcinoma: A review

Merkel cell carcinoma has been a focus of active scientific investigation in recent years and new information on the topic has emerged. Although uncommon, this primary cutaneous neuroendocrine carcinoma, usually involving the head/neck of elderly individuals, has a poor prognosis. Within the past two decades, an increase in the incidence of the tumor and the discovery of its link to the Merkel cell polyomavirus have focused medical attention on the lesion. The resulting studies have improved our understanding of the biology of the neoplasm and contributed to clinical care. Specifically, two pathogenic subsets of the tumor have come to light, the majority due to Merkel cell polyomavirus and the minority caused by ultraviolet radiation-induced genetic damage. This dichotomy carries prognostic implications favoring the former subset. In addition, having capitalized on the known susceptibility of the tumor to immune influences, investigators have recently discovered its responsiveness to immune checkpoint inhibition. This revelation has constituted a therapeutic milestone at the clinical level. Herein we provide an overview of the topic, outline updates in the field and place an emphasis on dermatopathologic aspects of Merkel cell carcinoma.

Exploring the Prognostic Role of Ki67 Proliferative Index in Merkel Cell Carcinoma of the Skin: Clinico-Pathologic Analysis of 84 Cases and Review of the Literature

The exact prediction of outcome of patients with Merkel cell carcinoma (MCC) of the skin is difficult to determine, although several attempts have been made to identify clinico-pathologic prognostic factors. The Ki67 proliferative index is a well-known marker routinely used to define the prognosis of patients with neuroendocrine neoplasms. However, its prognostic value has been poorly investigated in MCC, and available published results are often contradictory mainly because restricted to small series in the absence of standardized methods for Ki67 evaluation. For this reason, we explored the potential prognostic role of Ki67 proliferative index in a large series of MCCs using the WHO standardized method of counting positive cells in at least 500 tumor cells in hot spot areas on camera-captured printed images. In addition, since MCC may be considered as the cutaneous counterpart of digestive neuroendocrine carcinomas (NECs), we decided to stratify MCCs using the available and efficient Ki67 threshold of 55%, which was found prognostic in digestive NECs. This choice was also supported by the Youden index analysis. In addition, we analyzed the prognostic value of other clinico-pathologic parameters using both univariate and multivariate analysis. Ki67 index appeared significantly associated with prognosis at univariate analysis together with stage IV, lack of MCPyV, and p63 expression, but not at the multivariate analysis, where survival resulted independently influenced by p63 expression and tumor stage, only.

TdT Expression Is a Marker of Better Survival in Merkel Cell Carcinoma, and Expression of B-Cell Markers Is Associated With Merkel Cell Polyomavirus

OBJECTIVES

Merkel cell carcinoma is a rare but very aggressive cutaneous tumor. We evaluated the prognostic potential of B-cell markers (terminal deoxynucleotidyl transferase [TdT], PAX5, CD117), follicular stem cell markers (CK15, CK19), p63, p53, RB, and Merkel cell polyomavirus (MCPyV; CM2B4) in 136 primary cutaneous Merkel cell carcinomas.

METHODS

Clinical, histopathologic, and immunohistochemical analyses were performed. The results were correlated with patient outcomes by Fisher exact test, log-rank tests, and Cox multivariate models.

RESULTS

By Fisher exact test, although TdT significantly correlated with both lack of progression (P = .0087) and alive status (P = .0056), MCPyV status correlated only with alive status (P = .031). In univariate analyses, TdT, MCPyV, and RB significantly correlated with improved overall survival, whereas p63 and CK15 correlated with worse overall survival. However, in multivariate analyses, only TdT expression remained as an independent predictor of improved overall survival, Merkel cell carcinoma-specific survival, and progression-free survival. By linear regression analyses, significant correlations between MCPyV vs TdT, PAX5, and CD117 were observed.

CONCLUSIONS

TdT expression is a potential marker of better survival in Merkel cell carcinoma. Expression of B-cell markers is associated with MCPyV, suggesting that clonal viral integration might play a role in the expression of these markers.

p63 expression in Merkel cell carcinoma: comparative immunohistochemistry invokes TAp63 as the dominant isoform involved

The literature suggests that p63 expression in Merkel cell carcinoma (MCC) is associated with a poor prognosis. p63 immunohistochemistry marks the 2 main isoforms of this transcriptional protein: TAp63 (tumor suppressor-like properties) and ∆Np63 (oncogenic properties). Little information about the isoform of relevance in MCC exists. p40 immunohistochemistry specifically marks ∆Np63, and using comparative, semiquantitative expression of p63 and p40, we sought to clarify the issue. Our cohort of 53 cases (28 men and 25 women, median age 79 years, interquartile range 71-88) was stratified by morphology and viral status. Immunohistochemistry (p63, p40, and cytokeratin 5/6) was performed, H-scores for nuclear expression of p63 and p40 were derived (2 observers; positivity ≥ 10), and interobserver agreement was evaluated. Clinical, pathological, and outcome data were documented. The results were analyzed statistically. Mortality amounted to 57% (median follow-up 686 days, interquartile range 292-1599). Positivity for Merkel cell polyomavirus was observed in 29 (55%) of cases. Expression of p63 and p40 was present in 36 (69%) and 4 (8%) of cases, respectively. Increased age (P = .0241), negative Merkel cell polyomavirus status (P = .0185), and p63 positivity (P = .0012) were significantly associated with mortality. The latter 2 variables were highly correlated (P = .004). The interclass correlation between the 2 sets of H-scores was 0.95. Our findings support an association between p63 expression and reduced overall survival in MCC and show consistency in scoring this prognostic parameter. TAp63 is the dominant isoform of the protein involved. The paradoxical tumor suppressor-like activity of this isoform in p63-positive MCCs with reduced overall survival requires further study.

p63 Is a Promising Marker in the Diagnosis of Unusual Skin Cancer

Skin cancer is the most common type of cancer worldwide. Ozone depletion and climate changes might cause a further increase in the incidence rate in the future. Although the early detection of skin cancer enables it to be treated successfully, some tumours can evolve and become more aggressive, especially in the case of melanoma. Therefore, good diagnostic and prognostic markers are needed to ensure correct detection and treatment. Transcription factor p63, a member of the p53 family of proteins, plays an essential role in the development of stratified epithelia such as skin. In this paper, we conduct a comprehensive review of p63 expression in different types of skin cancer and discuss its possible use in the diagnosis and prognosis of cutaneous tumours.

S2k guidelines for Merkel cell carcinoma (MCC, neuroendocrine carcinoma of the skin) - update 2018

Merkel cell carcinoma (MCC, ICD-O M8247 / 3) is a rare malignant primary skin tumor with epithelial and neuroendocrine differentiation. The neoplastic cells share many morphological, immunohistochemical and ultrastructural characteristics with Merkel cells of the skin. The diagnosis of MCC is rarely made on clinical grounds. Histological and immunohistochemical studies are usually required to confirm the clinical suspicion. Given the frequent occurrence of occult lymph node metastasis, sentinel lymph node biopsy should be performed once distant metastasis has been ruled out by cross-sectional imaging. Primary tumors without evidence of organ metastases are treated with complete surgical excision with appropriate surgical margins. Radiation therapy should be considered at all stages of the disease. For advanced MCC that is no longer amenable to curative treatment by surgery or radiation therapy, there is currently no established systemic therapy for which an improvement in recurrence-free survival or overall survival has been demonstrated in a prospective randomized trial. However, immunotherapy using PD-1/PD-L1 blockade seems to be superior to chemotherapy. Various factors warrant that further diagnostic and therapeutic interventions be determined by an interdisciplinary tumor board. These factors include the tumor's aggressiveness, the frequent indication for sentinel lymph node biopsy along with the frequent occurrence in the head and neck region, the potential indication for adjuvant radiation therapy as well as the complexity of the required diagnostic workup.

Update on eighth edition American Joint Committee on Cancer classification for Merkel cell carcinoma and histopathological parameters that determine prognosis

Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine carcinoma. The annual incidence of MCC is increasing in the USA. Timely diagnosis and proper staging of this tumour are crucial as MCC has high rates of regional recurrence and lymph node and distant metastasis. In this review, we outline the key differences between the tumor node metastasis (TNM) staging criteria for MCC in the seventh and eighth editions of the AJCC Cancer Staging Manual We also discuss histopathological parameters that are not included in the eighth edition of the manual but have been shown in other studies to predict a worse prognosis in patients with MCC. Correct assessment and reporting of these clinically relevant histopathological parameters is of utmost importance for practising pathologists as management differs according to the stage of the tumour. This review aims to increase awareness of all these parameters, and proper recognition would guide the treating clinicians towards the most appropriate treatment options that can be given to patients.

Estrogen receptor β in Merkel cell carcinoma: its possible roles in pathogenesis

Sex steroids have been postulated to influence skin development and functions as well as its pathogenesis. MCC occurs in both sexes; however, the specific differences in pathogenesis among sexes have yet to be conclusively defined. The detailed status of sex steroid receptors (AR, PRA and PRB, and ERα, ERβ) are also unknown in MCC patients. We first immunolocalized sex steroid receptors and compared the results with immunolocalization of relevant transcription factors including SOX2, FOXA1, and Bcl-2 and Ki-67 in 18 cases of MCCs. AR, PRA, PRB, ERα, ERβ, Bcl-2, SOX2, and FOXA1 immunoreactivity was evaluated by using the modified H score method, and Ki-67 was quantified using labeling index. ERβ immunoreactivity was markedly present in all the cases of MCC examined, with relatively weak immunoreactivity of ERα, AR, PRA, and PRB. The status of ERβ immunoreactivity was also significantly correlated with Ki-67 labeling index and Bcl-2 score. These results demonstrated that ERβ could be associated with regulation of both cell proliferation and apoptosis in MCCs.

Density, Distribution, and Composition of Immune Infiltrates Correlate with Survival in Merkel Cell Carcinoma

PURPOSE

Merkel cell carcinoma (MCC) is an aggressive cancer with frequent metastasis and death with few effective therapies. Because programmed death ligand-1 (PD-L1) is frequently expressed in MCC, immune checkpoint blockade has been leveraged as treatment for metastatic disease. There is therefore a critical need to understand the relationships between MCPyV status, immune profiles, and patient outcomes.

EXPERIMENTAL DESIGN

IHC for CD3, CD8, PD-1, PD-L1, and MCPyV T-antigen (to determine MCPyV status) was performed on 62 primary MCCs with annotated clinical outcomes. Automated image analysis quantified immune cell density (positive cells/mm²) at discrete geographic locations (tumor periphery, center, and hotspot). T-cell receptor sequencing (TCRseq) was performed in a subset of MCCs.

RESULTS

No histopathologic variable associated with overall survival (OS) or disease-specific survival (DSS), whereas higher CD3⁺ (P = 0.004) and CD8⁺ (P = 0.037) T-cell density at the tumor periphery associated with improved OS. Higher CD8⁺ T-cell density at the tumor periphery associated with improved DSS (P = 0.049). Stratifying MCCs according to MCPyV status, higher CD3⁺ (P = 0.026) and CD8⁺ (P = 0.015) T-cell density at the tumor periphery associated with improved OS for MCPyV⁺ but not MCPyV^- MCC. TCRseq revealed clonal overlap among MCPyV⁺ samples, suggesting an antigen-specific response against a unifying antigen.

CONCLUSIONS

These findings establish the tumor-associated immune infiltrate at the tumor periphery as a robust prognostic indicator in MCC and provide a mechanistic rationale to further examine whether the immune infiltrate at the tumor periphery is relevant as a biomarker for response in ongoing and future checkpoint inhibitor trials in MCC. Clin Cancer Res; 22(22); 5553-63. ©2016 AACR.

Merkel Cell Carcinoma: Current Issues Regarding Diagnosis, Management, and Emerging Treatment Strategies

Merkel cell carcinoma (MCC) is a rare but aggressive cutaneous tumor with a predilection for the head and neck of elderly Caucasian patients. Although much less common than melanoma, MCC has higher rates of sentinel lymph node involvement, local and regional recurrences, and mortality. The majority of MCC cases have been linked to the relatively newly discovered Merkel cell polyomavirus, which is a ubiquitous constituent of the skin flora. Recent discoveries regarding viral integration and carcinogenesis and the immunologic features of MCC have expanded the understanding of MCC. These discoveries have led to the development and application of emerging therapies such as somatostatin analogs, immune checkpoint inhibition, adoptive cell therapy, and other exciting possibilities for targeted therapy.

Both tumor depth and diameter are predictive of sentinel lymph node status and survival in Merkel cell carcinoma

BACKGROUND

The purposes of this study were 1) to determine the impact of primary tumor-related factors on the prediction of the sentinel lymph node (SLN) status and 2) to identify clinical and pathologic factors associated with survival in Merkel cell carcinoma (MCC).

METHODS

An institutional review board-approved, retrospective review of patients with MCC treated between 1988 and 2011 at a single center was performed. Patients were categorized into 5 groups: 1) negative SLN, 2) positive SLN, 3) clinically node-negative but SLN biopsy not performed, 4) regional nodal disease without a known primary tumor, and 5) primary MCC with synchronous clinically evident regional nodal disease. Factors predictive of the SLN status were analyzed with logistic regressions, and overall survival (OS) and disease-specific survival (DSS) were analyzed with Cox models and competing risk models assuming proportional hazards, respectively.

RESULTS

Three hundred seventy-five patients were analyzed, and 70% were male; the median age was 75 years. The median tumor diameter was 1.5 cm (range, 0.2-12.5 cm), and the median tumor depth was 4.8 mm (range, 0.3-45.0 mm). One hundred ninety-one patients underwent SLN biopsy, and 59 (31%) were SLN-positive. Increasing primary tumor diameter and increasing tumor depth were associated with SLN positivity (P = .007 and P = .017, respectively). Age and sex were not associated with the SLN status. Immunosuppression, increasing tumor diameter, and increasing tumor depth were associated with worse OS (P = .007, P = .003, and P = .025, respectively). DSS differed significantly by group and was best for patients with a negative SLN and worst for those with primary MCC and synchronous clinically evident nodal disease (P = .018).

CONCLUSION

For patients with MCC, increasing primary tumor diameter and increasing tumor depth are independently predictive of a positive SLN, worse OS, and worse DSS. Tumor depth should be routinely reported when primary MCC specimens are being evaluated histopathologically.

PD-L1 Expression and Tumor-Infiltrating Lymphocytes Define Different Subsets of MAPK Inhibitor-Treated Melanoma Patients

PURPOSE

To evaluate the expression of tumor PD-L1 and changes in tumor-infiltrating lymphocyte (TIL) populations in patients with metastatic melanoma treated with targeted MAPK inhibitors.

EXPERIMENTAL DESIGN

Ninety-three tumors were analyzed from 40 patients treated with a BRAF inhibitor alone (BRAFi; n = 28) or combination of BRAF and MEK inhibitors (Combi; n = 12). Tumors were excised before treatment (PRE), early during treatment (EDT), and at progression (PROG). Immunohistochemical staining was performed for CD4, CD8, CD68, FOXP3, LAG3, PD-1, and PD-L1 and correlated with clinical outcome.

RESULTS

Patients' tumors that were PD-L1 positive at baseline showed a significant decrease in PD-L1 expression at PROG (P = 0.028), whereas patients' tumors that were PD-L1 negative at baseline showed a significant increase in PD-L1 expression at PROG (P = 0.008) irrespective of treatment with BRAFi or Combi. Overall PD-L1 expression highly correlated with TIL immune markers. BRAFi-treated patients showed significant increases in CD4(+), CD8(+), and PD-1(+) lymphocytes from PRE to EDT (P = 0.001, P = 0.001, P = 0.017, respectively), and Combi-treated patients showed similar increases in CD4(+) and CD8(+) lymphocytes from PRE to EDT (P = 0.017, P = 0.021).

CONCLUSIONS

The addition of MEKi to BRAFi did not result in significant reduction in immune infiltration in EDT biopsies. This provides support for conducting trials that combine MAPKi with immune checkpoint inhibitors in the hope of improving complete and durable response rates. PD-L1 expression at PROG on MAPK inhibitors varied according to baseline expression suggesting that combining MAPKi with immunotherapies concurrently may be more effective in patients with PD-L1 expression and TILs in baseline melanoma samples.

Neuroendocrine tumors: beyond the abdomen

Several classification systems for neuroendocrine tumors (NETs) exist, which use variable terminology and criteria for grading and staging. This variability in terminology can cause confusion and difficulty in recognizing which tumors are, in fact, members of this heterogeneous group of malignancies. The largest group of NETs, the gastroenteropancreatic NETs, has been well described and characterized; however, there are less-recognized extra-abdominal NETs that can arise from nearly any organ in the body. In this article, the clinical features and imaging appearances of the extra-abdominal NETs will be reviewed, compared, and contrasted. This diverse group consists of paragangliomas, Merkel cell carcinomas, esthesioneuroblastomas, NETs of the lung, and medullary thyroid carcinomas. Recognition of these tumors as part of the larger group of NETs is important for understanding how best to approach imaging for their diagnosis, staging, and potential treatment. Familiarity with the computed tomographic and magnetic resonance imaging appearances and the role of radionuclide imaging of these heterogeneous groups aids in the correct diagnosis and in treatment planning.

Mutational analysis of merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine malignancy that is associated with a poor prognosis. The pathogenesis of MCC is not well understood, and despite a recent plethora of mutational analyses, we have yet to find a set of signature mutations implicated in the majority of cases. Mutations, including TP53, Retinoblastoma and PIK3CA, have been documented in subsets of patients. Other mechanisms are also likely at play, including infection with the Merkel cell polyomavirus in a subset of patients, dysregulated immune surveillance, epigenetic alterations, aberrant protein expression, posttranslational modifications and microRNAs. In this review, we summarize what is known about MCC genetic mutations and chromosomal abnormalities, and their clinical significance. We also examine aberrant protein function and microRNA expression, and discuss the therapeutic and prognostic implications of these findings. Multiple clinical trials designed to selectively target overexpressed oncogenes in MCC are currently underway, though most are still in early phases. As we accumulate more molecular data on MCC, we will be better able to understand its pathogenic mechanisms, develop libraries of targeted therapies, and define molecular prognostic signatures to enhance our clinicopathologic knowledge.

Molecular pathology of skin neoplasms of the head and neck

CONTEXT

Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region.

OBJECTIVE

To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations.

DATA SOURCES

Literature review.

CONCLUSIONS

Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.

Working formulation of neuroendocrine tumors of the skin and breast

In the skin and breast, endocrine tumors are composed of a heterogeneous mixture of endocrine and exocrine cells. The definition of "pure" endocrine carcinomas is a matter for debate, and as a consequence, there is lack of uniform diagnostic criteria. There are no significant clinical differences in either overall or disease-free survival between matched neoplasms with endocrine and without endocrine differentiation nor between the degree of endocrine differentiation and tumor size, stage, or prevalence of vascular invasion for both sites (skin and breast). Here, endocrine tumors of the skin and breast are grouped respectively into three categories that include most of the neuroendocrine tumors of the skin and breast as seen in routine practice. It was felt that the number of different types of neuroendocrine tumors is so conspicuous that it is impossible to organize them in an orderly classification. It has been proposed therefore, for practical diagnostic routine purposes, to arrange these neoplasms into a working formulation. The latter includes heterogeneous lesions respectively of the skin and breast within the same group that have clinical features in common.

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.

Giant Merkel cell carcinoma of the lower limb: case report and review of the literature

BACKGROUND

Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine malignancy that usually grows rapidly at the head and neck. Giant forms at the lower limbs are rarely reported and usually affect patients in the eighth decade or older.

METHODS

We report the case of a 60-year-old man who presented with a giant MCC on his right thigh. We managed this case by applying the 2012 updated guidelines and reviewed all cases of giant MCC of the lower limbs reported in the literature.

RESULTS

At the 4-month follow-up, the patient showed complete remission.

CONCLUSION

Giant forms of MCC are still treated as typical cases of MCC, when these patients show a very poor prognosis. In young and adult people, such as our case, wide surgical excisions, sentinel lymph node biopsy in clinically negative node cases, radiotherapy of the regional drain area, and a strict follow-up should be routinely performed to improve patients' survival.

Support for p63 expression as an adverse prognostic marker in Merkel cell carcinoma: report on a Canadian cohort

Recent evidence has invoked immunohistochemical expression of p63 in Merkel cell carcinoma as an adverse prognostic factor. Conflicting data led us to evaluate this. An Eastern Canadian cohort diagnosed between 1990 and 2012 was studied. Demographic and clinical data were obtained from pathology records and Provincial Cancer Registries. Pathological features were evaluated by the investigators. Merkel cell polyomavirus status was known in a subset of cases. Clinicopathological features were correlated with overall survival. The cohort consisted of 83 patients (mean age, 75.8 ± 11.7 years) with a male/female ratio of 1.24:1. In a mean follow-up period of 175 weeks (±177), 51 patients died (61.4%). Of several parameters examined, 6 showed significant adverse associations with survival on univariate analysis: age (hazard ratio [HR], 1.05 [1.02-1.08]), clinical stage (III/IV versus I/II; HR, 2.24 [1.18-4.27]), tumor size (HR, 1.16 [1.05-1.28]), combined versus pure morphology (HR, 1.82 [1.04-3.18]), minimal tumor-infiltrating lymphocytes (HR, 2.23 [1.04-4.78]), and expression of p63 (positive in 49.4%; HR, 1.93 [1.09-3.43]). In the stage I/II subgroup, p63 expression was associated with a trend toward poor survival. On multivariate analysis, p63 expression was not significantly associated with reduced survival. Our data support existing evidence that p63 expression in Merkel cell carcinoma carries adverse implications for survival. That it was not an independent prognostic factor may be due to study size and/or its potential as a confounding variable with clinical stage. Of clinical importance is its association with a trend toward a poor outcome in early stage disease.

p63 expression in Merkel cell carcinoma predicts poorer survival yet may have limited clinical utility

OBJECTIVES

To determine the clinical utility of p63 expression, which has been identified in several cohorts as a predictor of poorer prognosis in Merkel cell carcinoma (MCC).

METHODS

Immunohistochemistry was used to determine p63 expression on MCC tumors from 128 patients.

RESULTS

Of the patients, 33% had detectable p63 expression. p63 Positivity was associated with an increased risk of death from MCC (hazard ratio, 2.05; P = .02) in a multivariate Cox regression model considering stage at presentation, age at diagnosis, and sex. Although p63 expression correlated with diminished survival in this largest cohort reported thus far, the effect was weaker than that observed in prior studies. Indeed, within a given stage, p63 status did not predict survival in a clinically or statistically significant manner.

CONCLUSIONS

It remains unclear whether this test should be integrated into routine MCC patient management.

Human Merkel cell polyomavirus: virological background and clinical implications

The Merkel cell polyomavirus (MCPyV), identified in humans in 2008, is associated with a relatively rare but aggressive neuroendocrine skin cancer, the Merkel cell carcinoma (MCC). MCC incidence is increasing due to the advancing age of the population, the increase in damaging sun exposure and in the number of immunocompromised individuals. MCPyV must be considered as the etiological agent of MCC and thus is the first example of a human oncogenic polyomavirus. MCPyV infection is common, and seroprevalence studies indicate that widespread exposure begins early in life. The majority of adults have anti-MCPyV antibodies and there is a growing body of evidence that healthy human skin harbors resident or transient MCPyV suggesting that MCPyV infection persists throughout life. However, the mode of transmission, the host cells, and the latency characteristics of this virus remain to be elucidated. In addition, it is still not clear whether MCPyV is associated with diseases or lesions other than Merkel cell carcinoma. The etiologic role of MCPyV in MCC opens up opportunities to improve the understanding of this cancer and to potentially improve its treatment.

[What's new in oncology?]

In cutaneous oncology, the year 2012 was marked by the consolidation of earlier results as well as the emergence of new therapeutic perspectives. The consolidated results most notably concern the use of MAP-kinase inhibitors (anti-MEK, anti-BRAF) in the treatment of patients with metastatic melanoma. Vismodegib (an SMO inhibitor), used in the treatment of multiple basocellular carcinomas that are inoperable or that have developed in patients suffering from Gorlin syndrome, has been the subject of publication of large-scale studies. Of the new therapeutic advances, let us mention the use of inhibitors or monoclonal antibodies directed against the PD1 receptor and its ligand PD-L1, the combination of MEK and BRAF inhibitors in the treatment of metastatic melanoma, and treatment in adjuvant situations with these same inhibitors. Beyond these significant advances that must be credited to cutaneous oncology, new questions are emerging relative to the side effects observed with these targeted therapies. The onset of multiple epidermoid carcinomas or primary melanomas treated with BRAF inhibitors is a striking illustration of the paradoxes arising from the clinical transfer of scientific progress. The intellectual perspectives are therefore numerous. It is hoped that this work will succeed in making these innovative drugs available to the patients who will have contributed to their development through their participation in clinical trials.

A cornucopia of human polyomaviruses

During the past 6 years, focused virus hunting has led to the discovery of nine new human polyomaviruses, including Merkel cell polyomavirus, which has been linked to Merkel cell carcinoma, a lethal skin cell cancer. The discovery of so many new and highly divergent human polyomaviruses raises key questions regarding their evolution, tropism, latency, reactivation, immune evasion and contribution to disease. This Review describes the similarities and differences among the new human polyomaviruses and discusses how these viruses might interact with their human host.