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

18 F-FDG and 18 F-AIF-NOTA-Octreotide PET/CT Confirmed a Rare Case of Cutaneous Merkel Cell Carcinoma With a Solitary Local Nodal Metastasis

ABSTRACT

Cutaneous Merkel cell carcinoma with local nodal metastasis is a rare entity. A 56-year-old man presented with a nontender left inguinal mass, and ultrasound-guided biopsy of this nodal mass confirmed nodal metastasis with strong neuroendocrine differentiation from cutaneous Merkel cell carcinoma. Staging 18 F-FDG PET/CT showed a solitary 3.9 × 6.8-cm hypermetabolic left groin mass with no other suspicious lesions elsewhere. To confirm the patient's eligibility for radical curative treatment, taking into consideration of its neuroendocrine differentiation, a subsequent 18 F-AIF-NOTA-octreotide PET/CT was performed, which demonstrated only solitary somatostatin receptor-positive left inguinal mass. The patient underwent radical treatment.

CM, Orsolini G, Prestianni P, Bonomo G, Funicelli L, Bertani E, Queirolo P, Ravizza D, Rubino M, Tosti G, Pennacchioli E. Nodal Merkel Cell Carcinoma with Unknown Primary Site and No Distant Metastasis: A Single-Center Series

Merkel cell carcinoma (MCC) is a very rare and aggressive neuroendocrine carcinoma originating from Merkel cells, typically with a skin nodule; however, it exceptionally presents with only a basin lymph node localization, with neither a cutaneous primary site nor distant metastases. From 1996 to 2020, among patients with histologically confirmed MCC managed at a neuroendocrine neoplasm-referral center, we selected those with an exclusive nodal basin, no distant metastasis, and an unknown primary site defined by cross-sectional and physical examination. A total of 55 out of 310 patients fulfilled the selection criteria. The median age was 64 years and the majority were males. Inguinal lymph-nodes were the most common anatomic site. With a median follow-up of 4.3 years, the 5-year relapse-free survival (RFS) rate was 56.6 (95% CI 42.0-68.8%) and the 5-year cancer specific survival (CSS) rate was 68.5 (95% CI 52.8-79.9%) for the whole population. The 36 patients (65.5%) undergoing lymphadenectomy (LND) + radiotherapy (RT) ± chemotherapy had a 5-year RFS rate of 87.2% (95% CI 65.5-95.7%) and a 5-year CSS rate of 90.5% (95% CI 67.0-97.5), which were better than those receiving LND alone. In a multivariable analysis, the survival benefit for LND + RT remained significant. Results from one of the largest single-center series of nMCC-UP suggest that a curative approach including RT can be effective, similar to what is observed for stage IIIB MCC. Multicentric studies with homogenous populations should be carried out in this controversial clinical entity, to minimize the risk of biases and provide robust data.

Merkel cell carcinoma of unknown primary: Clinical presentation and outcomes

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy that usually occurs in the head/neck or extremities. However, there are reports of MCC developing in the lymph nodes or parotid gland without evidence of a primary cutaneous lesion.

METHODS

We reviewed 415 patients with biopsy-proven MCC. Patients with MCC of unknown primary (n = 37, 9%, MCCUP) made up the study cohort. The primary endpoints of the study were rate of recurrence, disease-free survival, and overall survival.

RESULTS

Patients with MCCUP presented with tumors in lymph nodes (n = 34) or parotid gland (n = 3). Nodal disease was most commonly detected in the inguinal/external iliac (n = 15) or axillary (n = 14) regions. The mean age at diagnosis was 70 years and 24% were female. Patients presented with distant metastases in 24.3% of cases. Patients with stage IIIA disease treated with regional lymph node dissection (RLND) had a lower risk of disease recurrence (hazard ratio 0.26, p = 0.046). Recurrence-free survival was 59.3% at 5 years. Disease-specific survival was 63.3% at 5 years.

CONCLUSION

Patients with MCCUP have a high risk of recurrence and mortality. The optimal treatment for MCCUP has yet to be elucidated, although therapeutic RLND appears beneficial for these patients.

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.

Multimodal Strategy in Localized Merkel Cell Carcinoma: Where Are We and Where Are We Heading?

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumor of the skin whose incidence is rising. Multimodal treatment is crucial in the non-metastatic, potentially curable setting. However, the optimal management of patients with non-metastatic MCC is still unclear. In addition, novel insights into tumor biology and newly developed treatments (e.g., immune checkpoint inhibitors) that dramatically improved outcomes in the advanced setting are being investigated in earlier stages with promising results. Nevertheless, the combination of new strategies with consolidated ones needs to be clarified. We reviewed available evidence supporting the current treatment recommendations of localized MCC with a focus on potentially ground-breaking future strategies. Advantages and disadvantages of the different treatment modalities, including surgery, radiotherapy, chemotherapy, and immunotherapy in the non-metastatic setting, are analyzed, as well as those of different treatment modalities (adjuvant as opposed to neoadjuvant). Lastly, we provide an outlook of remarkable ongoing studies and of promising agents and strategies in the treatment of patients with non-metastatic MCC.

Not Your Typical Tonsil: Metastatic Merkel Cell Carcinoma or Primary Disease?

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumor that almost always presents as a cutaneous lesion in the sun-exposed areas on the bodies of elderly white males. Metastasis to lymph nodes in the presence or absence of a known primary site and occurrence of these tumors in non-sun-exposed sites have also been described; however, an incidence of recurrent disease arising in the palatine tonsil in the absence of any detectable primary lesion has never been reported in the literature. In this report, we discuss a case of a 72-year-old female who was found to have a single axillary lymph node, which was resected and proved to be positive forMCC of unknown primary (MCCUP). Since there was no evidence of additional disease, the patient elected not to pursue adjuvant therapies. Six and a half months later, she presented with a complaint of dysphagia and a right-sided exophytic tonsillar mass. Tonsillectomy revealed MCC with no detectable primary cutaneous lesion. She received adjuvant therapy with avelumab and demonstrated a complete response after one year of bi-weekly treatments. Seven months following cessation of adjuvant treatments, surveillance positron emission tomography (PET) revealed enlarged retroperitoneal, pretracheal, periaortic, and left axillary lymph nodes concerning for recurrence. She elected to forgo additional biopsies and restarted avelumab the following month. She continues to be followed up on a monthly basis.

Merkel cell carcinoma: A systematic review of the demographic and clinical characteristics of 847 cases in Japan

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine carcinoma of the skin associated with Merkel cell polyomavirus and immunosuppression. Although MCC incidence is rising worldwide, MCC has not been sufficiently investigated in Japan. This study aimed to determine MCC demographics in Japan, including incidence, age, sex, location, spontaneous regression, and pure/combined MCC. Using PubMed and Igaku Chuo Zasshi, 847 MCC cases between 1985 and 2015 were extracted, and the main epidemiological characteristics were described. The mean age of all patients was 77.5 years. Regarding the characterized lesions, 63.0% were located on the head and neck, 5.2% on the trunk, 12.6% on the upper limb, 15.1% on the lower limb, 3.5% on the buttocks, and 0.6% on the genitals. Histopathological information regarding the presence of other malignancies could be retrieved in 611 cases, and a coexisting malignancy, mainly squamous cell carcinoma and Bowen's disease, was present in 14.2%. Subcutaneous MCC was observed in 31 patients with a male : female ratio of 1.07 (16 men/15 women). Nodal lesions with unknown primary tumor location were described in 19 patients with a male : female ratio of 0.9 (nine men/10 women) and a mean age of 77.7 years. Of 640 evaluable cases, spontaneous regression developed in 9.1%. Among those 58 patients, the male : female ratio was 1:2.1 in 56 evaluable cases (18 men/38 women). Merkel cell polyomavirus was assessed in 180 patients, and the virus was detected in 31.1% and not detected in 68.9% of the patients. MCC is a rare disease in Japan, with incidence rates and male : female ratios differing from those in the USA and European countries. Besides, this study reveals the high frequency of subcutaneous MCC and MCC with divergent differentiation patterns and spontaneous regression in Japan compared to other countries.

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.

Treatment of Advanced Merkel Cell Carcinoma: Current Therapeutic Options and Novel Immunotherapy Approaches

Advanced Merkel cell carcinoma (MCC) is a very aggressive, rare neuroendocrine tumor of the skin with a high frequency of locoregional recurrence and metastasis, and a high mortality rate. Surgical resection, sentinel lymph node biopsy, and radiotherapy represent the gold standard of treatment in patients with localized disease, while chemotherapy has a significant role in the treatment of advanced disease. However, no definitive evidence on the survival impact of radiotherapy in the advanced stages has been provided to date, and response to chemotherapy remains brief in the majority of cases, indicating an urgent need for alternative approaches. Biological and genome sequencing studies have implicated multiple molecular pathways in MCC, thus leading to the development of new agents that target angiogenic factors, anti-apoptosis molecules, poly-ADP ribose polymerase, intracellular signal proteins such as the PI3K/AKT/mTOR pathway, and peptide receptors such as somatostatin receptors. More recently, immunotherapy agents such as avelumab, pembrolizumab, and nivolumab, which act by blocking the programmed cell-death (PD)-1/PD-L1 immune checkpoint, have shown promising results, especially in the advanced setting, and should now be considered standard of care for metastatic MCC. Current research is focusing on developing new immunotherapeutic strategies, identifying predictive biomarker to aid in the selection of patients responsive to immunotherapy, and defining combination approaches to increase efficacy in refractory 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.

18F-FDG and 68Ga-somatostatin analogs PET/CT in patients with Merkel cell carcinoma: a comparison study

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin tumor. Currently, 18F-fluoro-deoxy-glucose (18F-FDG) PET/CT is the functional imaging modality of choice. Few data are available on the use of 68Ga-somatostatin analogs. The aim of our study was to evaluate and compare the diagnostic performance of 18F-FDG and 68Ga-somatostatin analog PET/CT in MCC patients.

RESULTS

Fifteen patients (12 males, 3 females; median age 73 years; range 41-81 years) with histologically proven MCC (4 with unknown primary lesion) who underwent both 18F-FDG and 68Ga-somatostatin analog PET/CT for staging, re-staging, or treatment response assessment were retrospectively evaluated. Results of both studies were qualitatively analyzed and compared on a patient- and lesion-based analysis, using histology or clinical/radiological follow-up as reference standard for final diagnosis. According to final diagnosis, 8/15 patients had at least one MCC lesion and 7/15 had no evidence of disease. On a patient-based analysis, 18F-FDG and 68Ga-somatostatin analogs correctly classified as positive 8/8 (100% sensitivity) patients and as negative 6/7 (85.7% specificity) and 5/7 (71.4% specificity) patients, respectively, with no significant difference. On a lesion-based analysis, 18F-FDG detected 67/75 lesions (89%) and 68Ga-somatostatin analogs 69/75 (92%), with no significant difference. In four patients with unknown primary MCC, both tracers failed to identify the primary MCC site.

CONCLUSIONS

Our preliminary data suggest that 18F-FDG and 68Ga-somatostatin analog PET/CT provide good and equivalent diagnostic performance, adding interesting insights into the complex MCC biology. However, these results do not suggest that 18F-FDG PET/CT should be replaced by 68Ga-somatostatin receptor imaging, which should be performed in addition, according to clinical indication, to the perspective of "personalized medicine."

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.

Avelumab and other recent advances in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare but aggressive form of skin cancer that occurs in the elderly, is associated with UV radiation and immunosuppression. Initial treatment consists of wide excision with adjuvant radiation. Although the tumor is sensitive to chemotherapy, long-term survival is unusual and there had been no US FDA-approved drugs prior to 2017. The recognition that MCC is associated with the Merkel cell polyomavirus occurs more commonly in immune-compromised patients and tumors express PD-L1 suggested testing immunotherapy. A study of an anti-PD-L1 antibody, avelumab, in chemotherapy-refractory MCC demonstrated a response rate of 31.8% resulting in FDA approval in March 2017 and EMA in September 2017. This review will discuss the disease, role of avelumab and other emerging treatment strategies for MCC.

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.