The predictive value of imaging studies in evaluating regional lymph node involvement in Merkel cell carcinoma

Lymph Node Metastases from Non-Melanoma Skin Cancer of the Head and Neck

Non-melanoma skin cancer (NMSC) represents the most common malignancy in the world, comprising exceedingly common lesions such as basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) and rare lesions such as Merkel cell carcinoma. Risk factors are widely recognized and include ultraviolet (UV) light exposure, radiation exposure, immunosuppression, and many others. As a whole, survival and functional outcomes are favorable, but each histopathological subtype of NMSC behaves differently. Treatment regimens for the primary site usually include wide surgical excision and neck dissection in cases of clinically involved metastatic lymph nodes. The elective management of draining nodal basins, however, is a contested topic. Nearly all subtypes, excluding BCC, have a significant risk of lymphatic metastases, and have been studied with regard to sentinel lymph node biopsy (SLNB) and elective neck dissection. To date, no studies have definitively established a true single standard of care, as exists for melanoma, for any of the NMSCs. As a result, the authors have sought to summarize the current literature and identify indications and management options for the management of the cervical lymphatics for each major subtype of NMSC. Further research remains critically necessary in order to develop complete treatment algorithms.

Merkel cell carcinoma: epidemiology, clinical features, diagnosis and treatment of a rare disease

Merkel cell carcinoma is a rare skin cancer with neuroendocrine differentiation. The risk factors include sun exposure, advanced age, immunosuppression (such as transplant recipients, patients with lymphoproliferative neoplasms, or patients with HIV), and Merkel cell polyomavirus infection. Clinically, Merkel cell carcinoma appears as a cutaneous or subcutaneous plaque or nodule, but this tumor diagnosis is rarely made clinically. Therefore, histopathology and immunohistochemistry are usually necessary. Primary tumors without evidence of metastases are treated with complete surgical excision and appropriate surgical margins. The presence of occult metastasis in a lymph node is frequent and a sentinel lymph node biopsy should be performed. Postoperative adjuvant radiotherapy increases local tumor control. Recently, agents that block the PD-1/PD-L1 pathway have shown objective and durable tumor regression in patients with advanced solid malignancies. The first anti-PD-L1 antibody used in patients with Merkel cell carcinoma was avelumab, but pembrolizumab and nivolumab have also shown efficacy. This article describes the current state of knowledge of the epidemiology, diagnosis, and staging of Merkel cell carcinoma, as well as new strategies for its systemic treatment.

Diagnostic Test Accuracy of 18 F-FDG PET or PET/CT in Merkel Cell Carcinoma

OBJECTIVE

The purpose of the current study was to evaluate the diagnostic accuracies of 18 F-FDG PET or PET/CT for diagnosis of Merkel cell carcinoma (MCC) through a systematic review and meta-analysis.

METHODS

The PubMed, Cochrane database, and EMBASE database, from January 1990 to January 31, 2022, were searched for studies evaluating diagnostic performance of 18 F-FDG PET or PET/CT for MCC. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves.

RESULTS

Across 9 studies (259 patients), the pooled sensitivity of 18 F-FDG PET or PET/CT was 0.91 (95% confidence interval [CI], 0.85-0.95) and a pooled specificity of 0.93 (95% CI, 0.86-0.97). Likelihood ratio syntheses gave an overall LR+ of 14.0 (95% CI, 6.6-29.6) and LR- of 0.09 (95% CI, 0.05-0.17). The pooled diagnostic odds ratio was 153 (95% CI, 57-416).

CONCLUSION

18 F-FDG PET/CT showed an excellent performance for diagnosis of MCC. The likelihood ratio scattergram indicated that 18 F-FDG PET or PET/CT is useful for exclusion and confirmation of MCC. Further large multicenter studies would be necessary to substantiate the diagnostic accuracy of 18 F-FDG PET or PET/CT for MCC patients.

Positron Emission Tomography in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare neuroendocrine skin malignancy usually arising as a nonspecific nodule on sun-exposed areas of the head and neck. Given the poor prognosis of this aggressive tumor, assessment of disease burden in pre- and post-treatment care may ensure an optimal management with significant implications for patient surveillance and prognosis. Although imaging has established its role in locally advanced or distant metastatic MCC, a standard imaging algorithm is yet to be determined and respective recommendations are mainly based on melanoma. Positron emission tomography/computed tomography (PET/CT) is increasingly evolving as a valuable imaging tool in metastatic or unresectable MCC, mostly utilizing the glucose analogue 18F-fluorodeoxyglucose (18F-FDG) as a radiotracer. Despite being inferior in detecting the disease in its early stages compared to the "gold standard" of sentinel lymph node biopsy, recent evidence suggests an important role for 18F-FDG PET/CT in the routine workup of localized MCC. Moreover, 68Ga-labeled somatostatin analogues have been employed as PET tracers in the field of MCC with promising, yet comparable to 18F-FDG, results. This article provides a structured literature review of the most important studies investigating the role of PET or PET/CT in the clinical practice of MCC.

Merkel Cell Carcinoma: A 28-Year Experience

OBJECTIVE

To evaluate the management and recurrence outcomes of head and neck Merkel cell carcinoma (HN-MCC) at a single institution.

STUDY DESIGN

A retrospective review of outcomes in patients with HN-MCC.

SETTING

A tertiary center from May 1990 to December 2018.

SUBJECTS AND METHODS

Electronic medical records of patients with HN-MCC were reviewed.

RESULTS

Sixty cases were included, with 67% (40 of 60) males and a mean age of 73.3 years. Imaging had a moderate sensitivity and specificity for detection of occult disease when compared with histopathologic analysis. Forty-two percent (25 of 60) of patients underwent neck dissection, and 12% (7 of 60) had a sentinel lymph node biopsy (SLNB). There was a high rate of negative SLNB findings. The majority of patients were treated with surgery alone (29 of 60), followed by a cohort (21 of 60) treated with surgery plus adjuvant treatment, and 10 of 60 patients were treated with radiation therapy with or without chemotherapy. Recurrence-free survival was 50%, 45%, and 42% at 1, 2, and 5 years.

CONCLUSIONS

We report higher recurrence rates and higher negative SLNB result rates than other studies. Our results affirm that imaging may not be a substitute for SLNB and that it had an intermediate ability to identify the occult disease. Traditional predictors, including SLNB and cervical node pathology, may not identify patients at risk for recurrence in HN-MCC. We report similar recurrence rates in patients who had treatment of the cervical nodes by radiation therapy or neck dissection as compared with those who did not receive neck treatment.

Merkel Cell Carcinoma Therapeutic Update

OPINION STATEMENT

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin. Early-stage disease can be cured with surgical resection and radiotherapy (RT). Sentinel lymph node biopsy (SLNB) is an important staging tool, as a microscopic MCC is frequently identified. Adjuvant RT to the primary excision site and regional lymph node bed may improve locoregional control. However, newer studies confirm that patients with biopsy-negative sentinel lymph nodes may not benefit from regional RT. Advanced MCC currently lacks a highly effective treatment as responses to chemotherapy are not durable. Recent work suggests that immunotherapy targeting the programmed cell death receptor 1/programmed cell death ligand 1 (PD-1/PD-L1) checkpoint holds great promise in treating advanced MCC and may provide durable responses in a portion of patients. At the same time, high-throughput sequencing studies have demonstrated significant differences in the mutational profiles of tumors with and without the Merkel cell polyomavirus (MCV). An important secondary endpoint in the ongoing immunotherapy trials for MCC will be determining if there is a response difference between the virus-positive MCC tumors that typically lack a large mutational burden and the virus-negative tumors that have a large number of somatic mutations and predicted tumor neoantigens. Interestingly, sequencing studies have failed to identify a highly recurrent activated driver pathway in the majority of MCC tumors. This may explain why targeted therapies can demonstrate exceptional responses in case reports but fail when treating all comers with MCC. Ultimately, a precision medicine approach may be more appropriate for treating MCC, where identified driver mutations are used to direct targeted therapies. At a minimum, stratifying patients in future clinical trials based on tumor viral status should be considered as virus-negative tumors are more likely to harbor activating driver mutations.

Merkel Cell Carcinoma of the Head and Neck: Recommendations for Diagnostics and Treatment

Background

Merkel cell carcinoma (MCC) is a rare, aggressive tumor that often occurs in the head and neck region. Because of these features, the classifications and diagnostic and treatment regimens are frequently modified. Especially in the anatomically complex head and neck region, it is crucial to be aware of the current recommendations for diagnostics and treatment of MCC to ensure appropriate treatment. This overview aims to summarize the currently available literature.

Methods

The authors reviewed the relevant literature and international guidelines for MCC from 2012 to 2017 with respect to epidemiology and prognosis, diagnostic procedures and imaging, surgery, radiation, systemic treatment, and aftercare. These results were compared with existing guidelines, some of them current, and recommendations were derived.

Results

Marked developments in imaging have resulted in an increased use of functional imaging. The surgical concepts have changed regarding safety margins and the use of sentinel node biopsies. In systemic treatment, a move from conventional agents toward immuno-oncology can be observed.

Conclusions

For staging, it is important to be as exact as possible using functional imaging (e.g., positron emission tomography/computed tomography scan), especially in the head and neck area with its complex lymph drainage. This often plays an especially important role in early stages of the tumor, when the resection margin can be reduced to preserve the organ. Aftercare also should include functional imaging. In an advanced, metastatic stage, immuno-oncology (PD-1, PD-L1, CTLA-4) is superior to the previous methods of systemic treatment.

[Care of Merkel cell carcinoma and role of the radiotherapy]

Merkel cell carcinoma is a rare neuro-endocrine tumor of skin with a poor prognosis. Data available in literature are scarce. Current treatment for locoregional disease is based on combined treatment by surgery and radiotherapy. However these treatments are controversial. The aim of the present review is to sum up the different available studies and to compare national and international guidelines.

Merkel Cell Carcinoma: An Update of Key Imaging Techniques, Prognostic Factors, Treatment, and Follow-up

Merkel cell carcinoma, though rare, is one of the most aggressive tumors a dermatologist faces. More than a third of patients with this diagnosis die from the disease. Numerous researchers have attempted to identify clinical and pathologic predictors to guide prognosis, but their studies have produced inconsistent results. Because the incidence of Merkel cell carcinoma is low and it appears in patients of advanced age, prospective studies have not been done and no clear treatment algorithm has been developed. This review aims to provide an exhaustive, up-to-date account of Merkel cell carcinoma for the dermatologist. We describe prognostic factors and the imaging techniques that are most appropriate for evaluating disease spread. We also discuss current debates on treating Merkel cell carcinoma.

[Cutaneous Merkel cell carcinoma: role of 18FDG PET-CT]

Merkel cell carcinoma (MCC) is a rare neuroendocrine carcinoma of the skin with unpredictable evolution and high metastatic potential. This neoplasm usually occurs in the elderly on their sun-exposed areas. CCM constant greed for 18 fluorodeoxyglucose (FDG) defines the role of positron emission tomography (PET) in this pathology. However, no consensus has yet been reached. This study reports the case of a 25 year old woman treated for metastatic MCC, in order to draw attention to this particular tumor and to illustrate the role of 18 FDG PET in the management of this rare entity.

The utility of positron emission tomography with and without computed tomography in patients with nonmelanoma skin cancer

Combined positron emission tomography (PET) and computed tomography (CT) scans are widely used in the staging and monitoring of most malignancies. The differential for PET-positive cutaneous lesions includes primary skin cancers, infections, cutaneous metastases from distant malignancies, and benign neoplasms. In dermatology, PET/CT scans have been most widely studied in patients with melanoma and Merkel cell carcinoma. The role of PET/CT scans in the management of other cutaneous malignancies is less clear, but it has shown great promise in the management of patients with squamous cell carcinoma and cutaneous lymphoma. This review seeks to address the usefulness of PET/CT scans in nonmelanoma skin cancer and to provide guidance regarding the management of patients with incidental PET-positive nodules. Currently, there is limited experience with PET/CT scans for staging and monitoring of non-head and neck metastatic basal cell and squamous cell carcinomas, and results show limited sensitivity and specificity. We also address the evidence for management of an incidental PET-positive cutaneous nodule and recommend obtaining a biopsy specimen in patients with a known noncutaneous malignancy, a history of primary skin cancer, or a high risk of either cutaneous or noncutaneous malignancy.

Merkel cell carcinoma: Do you know your guidelines?

BACKGROUND

Merkel cell carcinoma (MCC) is a cutaneous neuroendocrine malignancy that exhibits clinically aggressive features and is associated with a poor prognosis. The incidence of MCC seems to be increasing for reasons unknown, and is estimated to be 0.32/100,000 in the United States.

METHODS

This article will review the current literature and National Comprehensive Cancer Network practice guidelines in the treatment of MCC.

RESULTS

Resection of MCC with negative margins remains the mainstay of therapy. Positive nodal disease should be treated with neck dissection and adjuvant radiotherapy. High-risk patients should undergo adjuvant radiotherapy, which improves oncologic outcomes. The role of chemotherapy is less clear and is currently reserved for advanced-stage MCC and palliative therapy.

CONCLUSION

The pathogenesis of MCC has recently been impacted with the discovery of the Merkel cell polyomavirus (MCPyV). Research to establish targeted and immunologic therapeutic options are ongoing.

Merkel cell carcinoma: An algorithm for multidisciplinary management and decision-making

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin. Therapeutic approach is often unclear, and considerable controversy exists regarding MCC pathogenesis and optimal management. Due to its rising incidence and poor prognosis, it is imperative to establish the optimal therapy for both the tumor and the lymph node basin, and for treatment to include sentinel node biopsy. Sentinel node biopsy is currently the most consistent predictor of survival for MCC patients, although there are conflicting views and a lack of awareness regarding node management. Tumor and node management involve different specialists, and their respective decisions and interventions are interrelated. No effective systemic treatment has been made available to date, and therefore patients continue to experience distant failure, often without local failure. This review aims to improve multidisciplinary decision-making by presenting scientific evidence of the contributions of each team member implicated in MCC management. Following this review of previously published research, the authors conclude that multidisciplinary team management is beneficial for care, and propose a multidisciplinary decision algorithm for managing this tumor.

Merkel cell carcinoma of the head and neck: pathogenesis, current and emerging treatment options

Merkel cell carcinoma (MCC) is a relatively uncommon, neuroendocrine, cutaneous malignancy that often exhibits clinically aggressive features and is associated with a poor prognosis. It typically presents as a painless, rapidly enlarging, dome-shaped red or purplish nodule in a sun-exposed area of the head and neck or upper extremities. Our understanding of MCC has increased dramatically over the last several years and the pathogenesis continues to be an area of active research. The etiology is likely multifactorial with immunosuppression, UV-induced skin damage, and viral factors contributing to the development of MCC. The recent discovery of Merkel cell polyomavirus has allowed for at least one aspect of disease development to be much better understood. In most cases, treatment consists of wide local excision with adjuvant radiation therapy. The role of chemotherapeutics is still being defined. The recent advancement of knowledge regarding the pathogenesis of MCC has led to an explosion research into novel therapeutic agents and strategies. This review seeks to summarize the current body of literature regarding the pathogenesis of MCC and potential targets for future therapies.

Incidence of Merkel cell carcinoma in Olmsted County, Minnesota: a population-based study

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive, often cutaneous malignancy. The incidence has been estimated from national registries in the USA and elsewhere, and data indicate variations depending on the region studied. The objective of this study was to determine the incidence of MCC in Olmsted County (MN, USA).

METHODS

Using the Rochester Epidemiology Project, which contains health records for all the residents of Olmsted County, we retrospectively reviewed the records for all cases of MCC from 1976 to 2011.

RESULTS

The overall annual age- and sex-adjusted incidence of MCC in Olmsted County during 1976-2011 was 0.35 per 100,000 person-years (95% CI, 0.14-0.57). The incidence tended to be higher among men than women with 0.69 per 100,000 (95% CI, 0.24-1.14) and 0.10 per 100,000 (95% CI, 0-0.24), respectively.

CONCLUSIONS

These data are within the range of previous MCC incidence reports, and the incidence of MCC in Olmsted County is consistent with rates reported in the remainder of the USA.

Focus on Merkel cell carcinoma: diagnosis and staging

Merkel cell carcinoma is a rare lymphophilic skin tumor of neuroendocrine origin with the potential for rapid progression. Small, localized lesions are diagnosed and treated clinically, but advanced tumors often undergo imaging evaluation. Due to its rarity, radiologists are unaware of evocative imaging features and usually do not consider Merkel cell carcinoma in the differential diagnosis of soft tissue tumors. Appropriate staging is important to determine appropriate treatment and has an impact on patient prognosis. Multimodality imaging is usually needed, and there is no consensus on the optimal imaging strategy. The purpose of this article is to review various aspects of Merkel cell carcinoma imaging and look in detail at how optimal multimodality staging should be carried out.

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.

Merkel cell carcinoma in East Yorkshire: A case series and literature review of current management

INTRODUCTION

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumour of the skin. The incidence is rising and it is associated with sun exposure and immunosuppression. Our aim was to perform a 10-year retrospective review of MCC treated in East Yorkshire and to examine disease progression, surgical and adjuvant management, and outcomes.

METHODS

A 10-year retrospective review was undertaken of patients identified through the histopathology database. Case notes and digital patient records were examined for patient demographics, disease characteristics, management and outcome. Disease stage was calculated using the 2010 AJCC TNM classification.

RESULTS

Thirty-seven patients with complete records were included. Twenty-one patients were male and 16 female, with mean age 76.7 years at presentation. Pre-malignant or malignant skin changes were documented in 15 patients, and immunosuppression in 15 patients. Mean duration of lesion was 17.5 weeks. Following diagnosis 22/37 patients underwent further surgery with 11 patients undergoing sentinel lymph node (LN) biopsy. LN disease was palpable at presentation in 8 patients. Three year survival is 40%.

CONCLUSIONS

There is no standardised management of MCC and randomised trials are challenging due to relatively small numbers. There has been little progress made in terms of improving survival. Development of a national database for patients with this condition would allow prospective data collection and more accurate assessment of current treatment protocols and their efficacy.

LEVEL OF EVIDENCE

IV.

Molecular imaging and therapy of merkel cell carcinoma

Several molecular imaging modalities have been evaluated in the management of Merkel cell carcinoma (MCC), a rare and aggressive tumor with a high tendency to metastasize. Continuous progress in the field of molecular imaging might improve management in these patients. The authors review the current modalities and their impact on MCC in this brief review article.

Somatostatin receptor expression in Merkel cell carcinoma as target for molecular imaging

Background

Merkel cell carcinoma (MCC) is a rare cutaneous neoplasm with increasing incidence, aggressive behavior and poor prognosis. Somatostatin receptors (SSTR) are expressed in MCC and represent a potential target for both imaging and treatment.

Methods

To non-invasively assess SSTR expression in MCC using PET and the radiotracers [⁶⁸Ga]DOTA-D-Phe¹-Tyr³-octreotide (DOTATOC) or -octreotate (DOTATATE) as surrogate for tumor burden. In 24 patients with histologically proven MCC SSTR-PET was performed and compared to results of computed tomography (CT).

Results

SSTR-PET detected primary and metastatic MCC lesions. On a patient-based analysis, sensitivity of SSTR-PET was 73% for nodal metastases, 100% for bone, and 67% for soft-tissue metastases, respectively. Notably, brain metastases were initially detected by SSTR-PET in 2 patients, whereas liver and lung metastases were diagnosed exclusively by CT. SSTR-PET showed concordance to CT results in 20 out of 24 patients. Four patients (17%) were up-staged due to SSTR-PET and patient management was changed in 3 patients (13%).

Conclusion

SSTR-PET showed high sensitivity for imaging bone, soft tissue and brain metastases, and particularly in combination with CT had a significant impact on clinical stage and patient management.

Diagnostic performance of fluorine-18-fluorodeoxyglucose positron emission tomography in patients with Merkel cell carcinoma: a systematic review and meta-analysis

BACKGROUND

Some studies reported the usefulness of fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) in patients with Merkel cell carcinoma (MCC).

OBJECTIVE

The aim of this study was to systematically review and meta-analyze published data about the diagnostic performance of 18F-FDG PET and PET/CT in patients with MCC.

METHODS

A comprehensive literature search of studies published through June 2013 regarding 18F-FDG PET and PET/CT in patients with MCC was performed. All retrieved studies were reviewed and qualitatively analyzed. Pooled sensitivity, specificity, positive and negative likelihood ratio (LR+ and LR−) and diagnostic odds ratio (DOR) of 18F-FDG PET or PET/CT in patients with MCC on a per examination-based analysis were calculated. The area under the summary receiver operating characteristic (ROC) curve was calculated to measure the accuracy of 18F-FDG PET or PET/CT in these patients.

RESULTS

Ten studies comprising 329 patients (549 scans) with MCC were included in the qualitative analysis (systematic review) and discussed. The quantitative analysis (meta-analysis) of six selected studies (including 92 patients with MCC) provided the following results on a per examination-based analysis: sensitivity was 90 % (95 % CI 80–96), specificity 98 % (95 % CI 90–100), LR+ 12 (95 % CI 4.3–33.0), LR− 0.15 (95 % CI 0.08–0.28), and DOR 86.8 (95 % CI 23–327). The area under the summary ROC curve was 0.96. No significant statistical heterogeneity between the studies was found.

CONCLUSIONS

In patients with MCC, 18F-FDG PET or PET/CT demonstrated high sensitivity and specificity, being accurate methods in this setting. Nevertheless, the literature focusing on the use of PET and PET/CT in MCC still remains limited. Prospective studies are needed to substantiate the high diagnostic accuracy of these methods in MCC.

Emerging and mechanism-based therapies for recurrent or metastatic Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine skin cancer with a disease-specific mortality of approximately 40 %. The association of MCC with a recently discovered polyomavirus, combined with the increased incidence and mortality of MCC among immunocompromised patients, highlight the importance of the immune system in controlling this cancer. Initial management of MCC is summarized within the NCCN guidelines and in recently published reviews. The high rate of recurrent and metastatic disease progression in MCC, however, presents a major challenge in a cancer that lacks mechanism-based, disease-specific therapies. Traditional treatment approaches have focused on cytotoxic chemotherapy that, despite frequent initial efficacy, rarely provides durable responses and has high morbidity among the elderly. In addition, the immunosuppressive nature of chemotherapy is of concern when treating a virus-associated cancer for which survival is unusually tightly linked to immune function. With a median survival of 9.6 months after development of an initial metastasis (n = 179, described herein), and no FDA-approved agents for this cancer, there is an urgent need for more effective treatments. We review diverse management options for patients with advanced MCC, with a focus on emerging and mechanism-based therapies, some of which specifically target persistently expressed viral antigens. These treatments include single-dose radiation and novel immunotherapies, some of which are in clinical trials. Due to their encouraging efficacy, low toxicity, and lack of immune suppression, these therapies may offer viable alternatives to traditional cytotoxic chemotherapy.

18F-fluorodihydroxyphenylalanine vs other radiopharmaceuticals for imaging neuroendocrine tumours according to their type

6-Fluoro-(¹⁸F)-L-3,4-dihydroxyphenylalanine (FDOPA) is an amino acid analogue for positron emission tomography (PET) imaging which has been registered since 2006 in several European Union (EU) countries and by several pharmaceutical firms. Neuroendocrine tumour (NET) imaging is part of its registered indications. NET functional imaging is a very competitive niche, competitors of FDOPA being two well-established radiopharmaceuticals for scintigraphy, ¹²³I-metaiodobenzylguanidine (MIBG) and ¹¹¹In-pentetreotide, and even more radiopharmaceuticals for PET, including fluorodeoxyglucose (FDG) and somatostatin analogues. Nevertheless, there is no universal single photon emission computed tomography (SPECT) or PET tracer for NET imaging, at least for the moment. FDOPA, as the other PET tracers, is superior in diagnostic performance in a limited number of precise NET types which are currently medullary thyroid cancer, catecholamine-producing tumours with a low aggressiveness and well-differentiated carcinoid tumours of the midgut, and in cases of congenital hyperinsulinism. This article reports on diagnostic performance and impact on management of FDOPA according to the NET type, emphasising the results of comparative studies with other radiopharmaceuticals. By pooling the results of the published studies with a defined standard of truth, patient-based sensitivity to detect recurrent medullary thyroid cancer was 70 % [95 % confidence interval (CI) 62.1–77.6] for FDOPA vs 44 % (95 % CI 35–53.4) for FDG; patient-based sensitivity to detect phaeochromocytoma/paraganglioma was 94 % (95 % CI 91.4–97.1) for FDOPA vs 69 % (95 % CI 60.2–77.1) for ¹²³I-MIBG; and patient-based sensitivity to detect midgut NET was 89 % (95 % CI 80.3–95.3) for FDOPA vs 80 % (95 % CI 69.2–88.4) for somatostatin receptor scintigraphy with a larger gap in lesion-based sensitivity (97 vs 49 %). Previously unpublished FDOPA results from our team are reported in some rare NET, such as small cell prostate cancer, or in emerging indications, such as metastatic NET of unknown primary (CUP-NET) or adrenocorticotropic hormone (ACTH) ectopic production. An evidence-based strategy in NET functional imaging is as yet affected by a low number of comparative studies. Then the suggested diagnostic trees, being a consequence of the analysis of present data, could be modified, for some indications, by a wider experience mainly involving face-to-face studies comparing FDOPA and ⁶⁸Ga-labelled peptides.

Imaging in patients with merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumor of the skin with a mortality rate of approximately 25% (Peloschek et al., 2010). Accurate assessment of nodal involvement in patients with MCC predicts significantly overall outcome (Smith et al., 2012 and Ortin-Perez et al., 2007). Due to the rarity of this highly aggressive disease, only a few imaging reports on MCC were published, and subsequently still to date no accepted imaging algorithm for MCC is available. For primary staging of MCC, general recommendations have included ultrasonography, chest X-ray CT, and MRI, but recent articles show that the use of sentinel node and FDG-PET/PET-CT is gaining more and more importance.

Prognostic factors in Merkel cell carcinoma: analysis of 240 cases

BACKGROUND

Knowledge regarding behavior of and prognostic factors for Merkel cell carcinoma (MCC) is limited.

OBJECTIVE

We sought to further understand the characteristics, behavior, prognostic factors, and optimal treatment of MCC.

METHODS

A multicenter, retrospective, consecutive study of patients with known primary MCC was completed. Overall survival and survival free of locoregional recurrence were calculated and statistical analysis of characteristics and outcomes was performed.

RESULTS

Among the 240 patients, the mean age at diagnosis was 70.1 years, 168 (70.0%) were male, and the majority was Caucasian. The most common location was head and neck (111, 46.3%). Immunosuppressed patients had significantly worse survival, with an overall 3-year survival of 43.4% compared with 68.1% in immunocompetent patients. In our study, patients with stage II disease had improved overall survival versus those with stage I disease, in a statistically significant manner. Patients with stage III disease had significantly worse survival compared with stage I and with stage II. Primary tumor size did not predict nodal involvement.

CONCLUSION

The data presented represent one of the largest series of primary MCC in the literature and confirm that MCC of all sizes has metastatic potential, supporting sentinel lymph node biopsy for all primary MCC. Because of the unpredictable natural history of MCC, we recommend individualization of care based on the details of each patient's tumor and clinical presentation.