Advances in Merkel cell carcinoma pathogenesis and management: a recently discovered virus, a new international consensus staging system and new diagnostic codes

Emerging Evidence for Infectious Causes of Cancer in the United States

Worldwide, infectious agents currently contribute to an estimated 15% of new cancer cases. Most of these (92%, or 2 million new cancer cases) are attributable to 4 infectious agents: Helicobacter pylori, human papillomavirus, and hepatitis B and C viruses. A better understanding of how infectious agents relate to the US cancer burden may assist new diagnostic and treatment efforts. We review US-specific crude mortality rates from infection-associated cancers and describe temporal and spatial trends since 1999. We review the US-specific evidence for infection-cancer associations by reporting available estimates for attributable fractions for the infection-cancer associations. Death due to cancers with established infectious associations varies geographically, but estimates for the US attributable fraction are limited to a few observational studies. To describe the burden of infection-associated cancer in the United States, additional observational studies are necessary to estimate the prevalence of infection nationally and within subpopulations. As infectious associations emerge to explain cancer etiologies, new opportunities and challenges to reducing the burden arise. Improved estimates for the United States would help target interventions to higher-risk subpopulations.

PD-L1 inhibition with avelumab for metastatic Merkel cell carcinoma

INTRODUCTION

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer that lacks durable responses to traditional chemotherapy. Areas covered: After MCC was shown to be an immunogenic tumor, small trials revealed high objective response rates to PD-1/PD-L1 checkpoint inhibitors. The JAVELIN Merkel 200 (NCT02155647) trial tested the use of avelumab, a human IgG1 monoclonal antibody against PD-L1, in metastatic MCC. Avelumab recently became the first approved drug for metastatic MCC. Expert commentary: By conducting broad phase I studies assessing the safety of avelumab and a small phase II study demonstrating efficacy in this rare orphan tumor type, avelumab gained accelerated approval for the treatment of metastatic MCC. Additional studies are needed to determine how the antibody-dependent cellular cytotoxicity (ADCC) competent Fc region of avelumab contributes to disease control. Remaining questions: Longer follow-up will determine the durability of checkpoint blockade in controlling metastatic MCC. Additional studies will assess the utility and safety of adjuvant checkpoint blockade in patients with excised MCC. How to increase response rates by combining PD-1/PD-L1 blockade with other treatment approaches needs to be explored. In addition, treatment options for MCC patients who fail or do not respond to avelumab need to be identified.

High-Frequency Ultrasound Examination in the Diagnosis of Skin Cancer

Ultrasound above 14 MHz images epidermis, dermis, and subcutaneous tissues in real time. Tumor depth is ascertained with B-mode. Three-dimensional imaging depicts nonpalpable, in-transit, and satellite lesions. Doppler blood flow technologies measure tumor neovascularity and map vascular structures. Three-dimensional Doppler histogram reconstruction measures tumor aggression and metastatic potential proportional to the percentage of malignant vessels. Subcutaneous investigation reveals nonpalpable metastatic disease and nodal basin lymphadenopathy. Adjacent nerves may be studied. Preservation of the fat-fascia border refines surgical staging of deeper malignancies. Image-guided biopsy is facilitated. Treatment under image guidance is optimized with radiation and various photo and thermal technologies.

Evaluating blood levels of neuron specific enolase, chromogranin A, and circulating tumor cells as Merkel cell carcinoma biomarkers

Background

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer. Although used to monitor MCC patients, the clinical utility of neuron-specific enolase (NSE) and chromogranin A (ChrA) blood levels is untested. EpCAM-positive circulating tumor cells (CTC) reflect disease status in several epithelial tumors. Here we investigate the use of NSE and ChrA blood levels and CTC counts as biomarkers for MCC disease behavior.

Methods

NSE and ChrA blood levels from 60 patients with MCC were retrospectively analyzed; 30 patients were additionally screened for CTC. Biomarker values were correlated to clinical parameters.

Results

Despite routine use by some physicians, NSE and ChrA blood levels did not correlate with progression free survival, disease specific survival, or MCC recurrence. We found CTC in 97% of tested MCC patients. CTC counts were elevated in patients with active disease, suggesting their potential use in monitoring MCC.

Conclusion

NSE and ChrA levels were not effective in predicting outcomes or detecting recurrences of MCC. In contrast, CTC counts have potential utility as a biomarker for MCC disease behavior.

Merkel cell carcinoma: a review and update on aetiopathogenesis, diagnosis and treatment approaches

Merkel cell carcinoma (MCC) or primary cutaneous neuroendocrine carcinoma is a relatively uncommon form of skin cancer. It is an aggressive neoplasm with high tendency for local recurrence and lymph node and distant metastasis, whose incidence has been rising in the last 2 decades.A novel polyomavirus (MCPyV) has been found in a significant proportion of MCCs, and this finding significantly contributed to the understanding of its pathogenesis.It is fairly consensual at the current state of know-ledge that appropriate staging, including sentinel lymph node biopsy, is very important in order to plan adequate treatment. Treatment includes aggressive surgery of the primary tumour and lymph node basin, commonly combined with adjuvant radiotherapy. Chemotherapy is usually reserved for distant metastasis.In the present article, the authors review the current knowledge about MCC with special emphasis on the new pathogenetic findings and current recommendations regarding management.

Clinical and dermoscopic characteristics of Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive cutaneous malignancy with a high mortality rate. Diagnosis is often delayed.

OBJECTIVES

To characterize the dermoscopic features of MCC.

METHODS

Clinical and dermoscopic images of 12 biopsy-proven MCCs were analysed in a retrospective manner, with existing dermoscopic criteria being scored independently by three dermatologists.

RESULTS

The four most frequent clinical features were cherry red colour, shiny surface, sharp circumscription and nodular morphology. Significant dermoscopic features included linear irregular and polymorphous vessels, poorly focused vessels, milky pink areas, white areas, structureless areas and architectural disorder. Pigmented structures were absent from all lesions.

CONCLUSIONS

The dermoscopic features described herein help the clinician to distinguish MCC from other benign and malignant red nodules. Increasing recognition of the presenting features will facilitate earlier diagnosis of MCC and reduced mortality.

Neuroendocrine tumors of the gynecologic tract: select topics

Tumors of the diffuse neuroendocrine cell system (DNES) may arise in any component of the gynecologic tract, including the vulva, vagina, cervix, endometrium, and ovary. Overall such tumors in the gynecologic tract are rare, constituting only 2% of gynecologic cancers, comprising a spectrum of tumors of variable biologic potential. Due to the rarity of such tumors, pathologists experience may be limited and these may present diagnostic challenges. Currently the nomenclature employed is still that of the pulmonary classification systems, carcinoid, atypical carcinoid, small and large cell neuroendocrine carcinoma that broadly correlates to low/grade 1, intermediate/grade 2, and high grade/grade 3 of the WHO gastroenteropancreatic neuroendocrine tumors classification. Furthermore in keeping with the lung, proliferative rate is assessed based on mitotic index rather than Ki-67 staining. In this review we cover select neuroendocrine tumors of the gynecologic tract.

Orbital metastasis secondary to merkel cell carcinoma: case report and literature review

INTRODUCTION

Merkel cell carcinoma is an aggressive malignancy often associated with metastatic spread, but has never been reported to metastasize to the orbit.

CASE

An 80 year old male with metastatic Merkel cell carcinoma presented with ptosis and extraocular movement abnormalities, and was found to have a lesion of the orbit consistent with metastatic spread. The lesion responded favorably to radiation therapy.

COMMENT

Although the orbit is a frequent site of metastatic disease, this is the first reported case of presumed Merkel cell carcinoma metastasizing to the orbit.

Merkel cell carcinoma: what do we know about it and what should we do?

Merkel cell carcinoma (MCC) is a rare primary cutaneous carcinoma of the skin that is highly aggressive, and has a high risk of locoregional and distant spread, a mortality rate considerably higher than that of cutaneous melanoma and poor survival. Its incidence has increased during the past twenty years. The studies published since 2008 have introduced changes in the understanding of its epidemiology and pathogenesis, and consequently the therapeutic approach. Despite this, there is still controversy surrounding its optimal management, which requires clarification. This is the purpose of this review.

Dermatology clinics: what's new in dermatopathology: news in nonmelanocytic neoplasia

This article reviews the recent dermatopathology literature involving nonmelanocytic neoplasia, with a focus on important work done over the last 5 years. The discussion includes advances in the understanding of Merkel cell carcinoma pathogenesis and prognosis; changes in the seventh edition of the American Joint Committee of Cancer staging manual in reference to staging of squamous cell carcinoma and Merkel cell carcinoma; newly described or rare histopathologic patterns and entities including squamoid eccrine ductal carcinoma, rippled-pattern adnexal neoplasms, onychomatricoma, spindle cell predominant trichodiscoma/neurofollicular hamartoma, and myoepithelioma; and microsatellite instability in sebaceous neoplasms of Muir-Torre syndrome and other tumors.

P-cadherin expression in Merkel cell carcinomas is associated with prolonged recurrence-free survival

BACKGROUND

 Merkel cell carcinoma (MCC) is a highly aggressive skin cancer, associated with advanced age, immunosuppression and Merkel cell polyomavirus (MCV) infections. As development and progression of cancer can be promoted by changes in cell adhesion proteins, we have previously analysed homo- and heterotypic cell-cell contacts of normal Merkel cells and MCCs and obtained indications for cadherin switching.

OBJECTIVES

To examine the prevalence and prognostic relevance of E-, N- and P-cadherin in MCCs.

METHODS

Paraffin-embedded MCC samples (n = 148) from 106 different patients were analysed by double-label immunostaining and immunofluorescence microscopy. MCV status was determined by real-time polymerase chain reaction. The cadherin repertoire and MCV status were correlated to clinical data, including tumour stage and recurrence-free survival.

RESULTS

Ninety-one per cent of all MCC were positive for N-cadherin whereas only 61·6% and 70·3% expressed E- and P-cadherin, respectively. P-cadherin was significantly more frequent in primary tumours than in lymph node metastases (81·9% vs. 40·9%, P = 0·0002). Patients with P-cadherin-positive primary tumours were in earlier tumour stages at initial diagnosis (P = 0·0046). Both in log-rank tests (P = 0·0474) and in multiple Cox regression analysis including age, sex, immunosuppression, stage at initial diagnosis and MCV status (hazard ratio 0·193, P = 0·0373), patients with P-cadherin-positive primary MCCs had significantly prolonged recurrence-free survival (mean 25·2 vs. 10·6 months; median 9·0 vs. 4·0 months). MCV DNA was detected in 78·2% of all MCC, more frequently in P-cadherin-positive MCC (P = 0·0008).

CONCLUSION

P-cadherin expression in MCCs predicts prolonged recurrence-free survival and may therefore indicate favourable prognosis.