Management of Merkel tumours: an evidence-based review

Cancer of the Vulva: A Review

BACKGROUND

Vulvar cancers, although rare, are becoming an increasingly serious threat to women's health. Cancer of the vulva accounted for 0.3% of all new cancers in the United States in 2019, with 6,070 newly diagnosed cases. This review details the epidemiology, pathogenesis, diagnosis, staging, and treatment of vulvar malignancies.

OBJECTIVE

To review cancer entities of the vulva, including vulvar intraepithelial neoplasms, squamous cell carcinoma (SCC), malignant melanoma, basal cell carcinoma, neuroendocrine tumors, and adenocarcinomas.

MATERIALS AND METHODS

Literature review using PubMed search for articles related to cancer of the vulva.

RESULTS

Vulvar intraepithelial neoplasms represent premalignant precursors to SCC of the vulva. There are several different histopathologic subtypes of SCC, and treatment is dependent on characteristics of primary tumor and lymph node involvement. Melanoma is the second most common cancer to affect the vulva, and staging is based on tumor, node, and metastatic spread.

CONCLUSION

Vulvar malignancies are rare, and diagnosis is dependent on biopsy and pathologic evaluation. Treatment for vulvar malignancies depends on histopathologic diagnosis but ranges from wide local excision with or without lymph node biopsy or dissection to radiation therapy with chemo- or immunotherapy. Overall survival varies by diagnosis.

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.

Clinical features and treatment of vulvar Merkel cell carcinoma: a systematic review

Background

Merkel cell carcinoma is a rare and aggressive neoplasm originating from mechanoreceptor Merkel cells of the stratum basale of the epidermis. Cases affecting the vulva are exceedingly rare, with the currently available literature primarily in case report form.

Body

Systematic review of the PubMed database returned 17 cases of Merkel cell carcinoma affecting the vulva. Patients presented at a mean age of 59.6 years with a firm, mobile vulvar mass. Symptoms of pain, erythema, pruritus, edema, and ulceration have been reported. Tumor histology is consistent with that of neuroendocrine tumors and typical Merkel cell carcinomas. Neuroendocrine and cytokeratin immunostains are frequently utilized in histopathological workup. Surgical management was the unanimous first-line therapy with adjuvant radiation in most cases. Recurrence occurred in 70.6% of patients at a mean follow-up of 6.3 months. Mortality was at 47.0% at a mean of 7.8 months after initial operation.

Conclusion

Merkel cell carcinoma affecting the vulva is an extremely rare and highly aggressive neoplasm. The present review of published cases serves to comprehensively describe the clinical course and treatment approaches for vulvar Merkel cell carcinoma.

Radiation Therapy is Associated with Improved Outcomes in Merkel Cell Carcinoma

BACKGROUND

Following wide excision of Merkel cell carcinoma (MCC), postoperative radiation therapy (RT) is typically recommended. Controversy remains as to whether RT can be avoided in selected cases, such as those with negative margins. Additionally, there is evidence that RT can influence survival.

METHODS

We included 171 patients treated for non-metastatic MCC from 1994 through 2012 at a single institution. Patients without pathologic nodal evaluation (clinical N0 disease) were excluded to reflect modern treatment practice. The endpoints included local control (LC), locoregional control (LRC), disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS).

RESULTS

Median follow-up was 33 months. Treatment with RT was associated with improved 3-year LC (91.2 vs. 76.9 %, respectively; p = 0.01), LRC (79.5 vs. 59.1 %; p = 0.004), DFS (57.0 vs. 30.2 %; p < 0.001), and OS (73 vs. 66 %; p = 0.02), and was associated with improved 3-year DSS among node-positive patients (76.2 vs. 48.1 %; p = 0.035), but not node-negative patients (90.1 vs. 80.8 %; p = 0.79). On multivariate analysis, RT was associated with improved LC [hazard ratio (HR) 0.18, 95 % confidence interval (CI) 0.07-0.46; p < 0.001], LRC (HR 0.28, 95 % CI 0.14-0.56; p < 0.001), DFS (HR 0.42, 95 % CI 0.26-0.70; p = 0.001), OS (HR 0.53, 95 % CI 0.31-0.93; p = 0.03), and DSS (HR 0.42, 95 % CI 0.26-0.70; p = 0.001). Patients with negative margins had significant improvements in 3-year LC (90.1 vs. 75.4 %; p < 0.001) with RT. Deaths not attributable to MCC were relatively evenly distributed between the RT and no RT groups (28.5 and 29.3 % of patients, respectively).

CONCLUSIONS

RT for MCC was associated with improved LRC and survival. RT appeared to be beneficial regardless of margin status.

Merkel cell carcinoma of the head and neck: challenges in implementing best practice

OBJECTIVE

Merkel cell carcinoma (MCC) is a rare, aggressive skin tumor. Controversies regarding optimal management persist due to inadequate data and knowledge regarding tumor biology. Head and neck MCC increases both oncological and reconstructive challenges, compounded by predominantly elderly patients. We review our practice and outcomes, review evidence, and discuss the difficulties in delivering best practice management.

METHODS

All patients with primary head and neck MCC, managed by a single multidisciplinary team between January 2001 and December 2010, were identified through retrospective analysis of a pathology coding database. A literature review was performed.

RESULTS

Twenty patients, with a mean age of 83.5 years (40-99 years) and presenting with mean symptom duration of 5 months, had primary tumors involving the nose (n = 2), periorbital region (n = 5), cheek (n = 6), and the temple and scalp (n = 7). Mean tumor size was 2.1 cm (range, 0.5-7.5 cm). Reconstructive techniques were direct closure (n = 8), skin grafting (n = 7), local flaps (n = 4), and free anterolateral thigh flap (n = 1). Two (10%) patients presented with nodal disease. Eight (40%) patients re-presented with nodal recurrence at a mean of 7 months with 6 undergoing salvage neck dissections. Adjuvant radiotherapy was completed in 5 cases, and chemotherapy used for palliation in 1 case. Most of the patients declined radiotherapy due to adverse effects or frailty.

CONCLUSIONS

Our series demonstrates the profound challenges in managing head and neck MCC, including tailoring definitive primary treatment and current consensus management to elderly patients. Regional nodal assessment and management remains crucial to achieving this goal.

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.

Regression of metastatic Merkel cell carcinoma following transfer of polyomavirus-specific T cells and therapies capable of re-inducing HLA class-I

Merkel cell carcinoma (MCC) is an aggressive skin cancer that typically requires the persistent expression of Merkel cell polyomavirus (MCPyV) oncoproteins that can serve as ideal immunotherapeutic targets. Several immune evasion mechanisms are active in MCC including down-regulation of HLA class-I expression on tumor cells and dysfunctional endogenous MCPyV-specific CD8 T cell responses. To overcome these obstacles, we combined local and systemic immune therapies in a 67-year-old man, who developed metastatic MCPyV-expressing MCC. Intralesional IFNβ-1b or targeted single-dose radiation was administered as a pre-conditioning strategy to reverse the down-regulation of HLA-I expression noted in his tumors and to facilitate the subsequent recognition of tumor cells by T cells. This was followed by the adoptive transfer of ex vivo expanded polyclonal, polyomavirus-specific T cells as a source of reactive antitumor immunity. The combined regimen was well-tolerated and led to persistent up-regulation of HLA-I expression in the tumor and a durable complete response in two of three metastatic lesions. Relative to historical controls, the patient experienced a prolonged period without development of additional distant metastases (535 days compared to historic median of 200 days, 95% confidence interval = 154-260 days). The transferred CD8(+) T cells preferentially accumulated in the tumor tissue, remained detectable and functional for >200 days, persisted with an effector phenotype, and exhibited evidence of recent in vivo activation and proliferation. The combination of local and systemic immune stimulatory therapies was well-tolerated and may be a promising approach to overcome immune evasion in virus-driven cancers.

Melanotic and non-melanotic malignancies of the face and external ear - A review of current treatment concepts and future options

Skin has the highest incidence and variety of tumors of all organs. Its structure is of great complexity, and every component has the potential to originate a skin neoplasm (SN). Because of its exposed nature, skin is vulnerable to carcinogenic stimuli such as UV radiation. Various entities can cause SN. Nonmelanotic skin cancers (NMSC) are the most common of all cancers, with over one million cases diagnosed annually in the US. Basal cell carcinoma (BCC) accounts for approximately 80% of all NMSC, most of the remaining 20% being squamous cell carcinoma (SCC). The skin of the head and neck is the most common site for tumors, accounting for more than 80% of all NMSC. BCC, SCC, and malignant melanomas (MM) represent 85-90% of all SN. Merkel cell tumors (MCC), lymphoepithelioma-like carcinomas of the skin (LELCS), dermato-fibro-sarcomas, leiomyosarkomas, and Kaposi-sarcomas are less frequent in the facial skin region and the external ear. Based on data from the German Federal Cancer Registry (2003/2004), 140,000 people in Germany were affected by SN (100,000 BCC, 22,000 SCC, 22,000 MM). This number increases considerably if malignant precursors, such as actinic keratosis, are included. Each year, the frequency of SN diagnosis rises by 3-7%. Among all known malignant tumors, MM exhibits the highest rate of increase in incidence. In the past, SN was primarily diagnosed in people aged 50 years or older. However, recently, the risk for developing SN has shifted, and younger people are also affected. Early diagnosis is significantly correlated with prognosis. Resection of SN creates defects that must be closed with local or microvascular flaps to avoid functional disturbing scar formation and deflection of the nose, eyelids, or lips. All therapeutic strategies for SN, the current standard for adjuvant and systemic treatment, and the management of the increasing number of patients under permanent blood thinner medication are described with regard to the treatment of SN.

Merkel cell carcinoma: chemotherapy and emerging new therapeutic options

Merkel cell carcinoma (MCC) is a rare neuroendocrine skin tumor that typically occurs in elderly, immunosuppressed patients. Infection with Merkel cell virus (MCV) and immunosuppression play an important role in the development of MCC. Different staging systems make it difficult to compare the existing clinical data. Furthermore, there predominantly exist single case reports and case series, but no randomized controlled trials. However, it is necessary to develop further therapy options because MCC tends to grow rapidly and metastasizes early. In the metastatic disease, therapeutic attempts were made with various chemotherapeutic combination regimens. Because of the high toxicity of these combinations, especially those established in SCLC, and regarding the unsatisfying results, the challenge is to balance the pros and cons of chemotherapy individually and carefully. Up to now, emerging new therapy options as molecular-targeted agents, for example, pazopanib, imatinib, or somatostatin analogues as well as immunologicals, for example, imiquimod and interferons, also showed less success concerning the disease-free response rates. According to the literature, neither chemotherapy nor molecular-targeted agents or immunotherapeutic strategies have shown promising effects in the therapy of the metastatic disease of MCC so far. There is a great demand for randomized controlled studies and a need for an MCC registry and multicenter clinical trials due to the tumors curiosity.

Multidisciplinary management in Merkel cell carcinoma

Herein, the authors describe the experience with the treatment of Merkel cell carcinoma (MCC) and review the literature regarding MCC treatment regimens. Nine patients underwent treatment due to stage I, II, or III MCC. The median follow up was 39 months. In five cases, tumors were excised with skin margins of >2 cm, and skin margins were <2 cm in four patients. Local adjuvant radiotherapy (RT) was given to four patients, while three patients underwent local lymphadenectomy (LAD). Local recurrence occurred in four patients who did not undergo RT (among them three patients had excision margins <2 cm) after a mean time of 9 months. Despite retreatment, two of those patients developed metastases. Recurrence-free survival after primary therapy was achieved: (a) in three patients with stage I and II MCC treated surgically with excision margins <2 cm combined with RT or wide excision >2 cm alone and (b) in two patients with stage III MCC treated with wide excision and LAD combined with local and regional RT. A review of the literature supports the following recommendations: (a) excision with adequate margins combined with RT; (b) LAD with regional RT in cases of lymph node involvement; and (c) sentinel lymph node biopsy in patients without clinically suspicious lymph nodes.

Incipient merkel cell carcinoma: a report of 2 cases

Merkel cell carcinoma is a malignant skin tumor with a poor prognosis that primarily affects photoexposed areas of elderly patients. Tumor size is a very strong prognostic factor, with much better outcomes associated with small lesions, measuring less than 1cm. However, such lesions are rarely seen in the clinic in view of the rapid growth of this tumor. We report 2 cases of incipient Merkel cell carcinoma. Both cases of incipient Merkel cell carcinoma measured approximately 5mm in diameter. One tumor was confined to the epidermis and papillary dermis on the nose of a 79-year-old man and the other was located in the deep dermis, almost in the hypodermis, on the buttock of an 82-year-old woman. In both cases, the lesions had appeared weeks earlier. The first tumor seemed to originate in the dermoepidermal junction whereas the second originated almost in the hypodermis. Although the lesions were at a similar disease stage and had a similar size, their different locations within the dermis highlight once again the controversy about which cells give rise to Merkel cell carcinoma. The precursor cells could feasibly be Merkel cells in the first case but not in the second.

Merkel cell carcinoma: recent insights and new treatment options

PURPOSE OF REVIEW

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin demonstrating a high propensity of recurrence and metastasis. Its 5-year disease-specific survival rate is only about 60%. Although MCC is still regarded as a very rare tumor entity, its incidence is rapidly increasing. In this regard, the American Cancer Society estimated almost 1500 new cases in the United States in 2008.

RECENT FINDINGS

The newly identified Merkel cell polyomavirus (MCV) has been found associated to most MCC cases. Nevertheless, the distinct molecular pathogenesis of MCC and its link to MCV is not yet fully understood. Moreover, the impact of MCV positivity on the course of disease and prognosis of MCC patients is controversially discussed.

SUMMARY

This review summarizes recent findings on MCC pathogenesis with a special emphasis on the impact of MCV, presents an overview of clinical aspects, and discusses treatment options.

Merkel cell carcinoma--pathogenesis, clinical aspects and treatment

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin demonstrating a high rate of recurrence and metastasis. Indeed, 5-year rates for MCC specific survival are only about 60%. Although MCCs' incidence is rapidly increasing, it is still a very rare tumour. In this regard, the American Cancer Society had estimated for 2008 almost 1500 new cases in the USA. Recently, the newly identified Merkel cell polyomavirus has been found associated with most of the MCC cases. Nevertheless, the pathogenesis of MCC is not yet fully understood. Here, we will summarize recent findings of the pathogenesis of MCC, present an overview of clinical aspects and discuss treatment options for MCCs.

Merkel cell carcinoma of skin-current controversies and recommendations

The review covers the current recommendations for Merkel cell carcinoma (MCC), with detailed discussion of many controversies. The 2010 AJCC staging system is more in-line with other skin malignancies although more complicated to use. The changes in staging system over time make comparison of studies difficult. A wide excision with margins of 2.5–3 cm is generally recommended. Even for primary </= 1 cm, there is a significant risk of nodal and distant metastases and hence sentinel node biopsy should be done if possible; otherwise adjuvant radiotherapy to the primary and nodal region should be given. Difficulties of setting up trials owing to the rarity of the disease and the mean age of the patient population result in infrequent reports of adjuvant or concurrent chemotherapy in the literature. The benefit, if any, is not great from published studies so far. However, there may be a subgroup of patients with high-risk features, e.g. node-positive and excellent performance status, for whom adjuvant or concurrent chemotherapy may be considered. Since local recurrence and metastases generally occur within 2 years of the initial diagnosis, patients should be followed more frequently in the first 2 years. However delayed recurrence can still occur in a small proportion of patients and long-term follow-up by a specialist is recommended provided that the general condition of the patient allows it. In summary, physician judgment in individual cases of MCC is advisable, to balance the risk of recurrence versus the complications of treatment.

Merkel cell carcinoma - a population-based epidemiological study in Finland with a clinical series of 181 cases

BACKGROUND

Merkel cell carcinoma (MCC) is a rare malignancy of the skin, and its incidence is reported to be rising. The purpose of this study was to calculate its incidence and survival ratios, and to describe the clinical characteristics of Merkel cell carcinoma patients in Finland.

METHODS

We calculated the incidence of MCC based on data from the Finnish Cancer Registry. In addition, patient files from hospitals and primary health care centres were reviewed for detailed data on the treatment and disease recurrence of 181 patients diagnosed with MCC in Finland during 1983-2004, and relative survival ratios were calculated for them.

RESULTS

The incidence (per 100,000) of MCC in Finland in 1989-2008 was 0.11 for men and 0.12 for women, adjusted for age to the world standard population. The mean age at diagnosis was 76 years (range 27-100), and 69% of the patients were women. The most common site of the primary tumour was the head and neck (53%). No extra benefit was gained from a wide surgical margin (≥ 2 cm) compared to a margin of 0.1-0.19 cm, but an intralesional excision was more often associated with local recurrence. None of the patients with Stage I-II disease who had received postoperative radiotherapy to the tumour bed had a local recurrence. The 5-year relative survival ratio amongst men was 36% (95% confidence interval 20-54%), and amongst women 69% (56 to -82%).

CONCLUSIONS

MCC is a rare disease in Finland, with incidence rates similar to those in the other Nordic countries. Our results support the view that complete excision with clear margins and post operative radiotherapy decrease local recurrences.

[Management for 145 cases of Merkel cell carcinoma]

PURPOSE

Merkel cell carcinoma (MCC)/primary cutaneous neuroendocrine carcinoma is a rare and aggressive malignant tumor. Optimal therapeutic strategy has not yet been established.

PATIENTS AND METHODS

Management of 145 patients from five centres was analysed. These data included ages, pathological stages, disease sites, histological and treatment details. Cause-specific (CSS) and overall survivals (OS) were analyzed by the Log-rank and Kaplan-Meier methods.

RESULTS

Median age was 78 years (47-95.2). We experienced 37 local, 37 regional and 15 distant relapses. In case of relapse, salvage therapy has been proposed whenever the general state of health condition of patient permitted it.

CONCLUSION

Our results for the treatment of relapse encourage multidisciplinary approach. Multicenter prospective trials are still needed to clarify and validate the optimal strategy.

The new polyomavirus (MCPyV) does not affect the clinical course in MCCs

Since 2008, a new polyomavirus (MCPyV) in Merkel cell carcinomas (MCC) has been described, but little is known about its impact on the clinical course. The purpose of this study was to determine the presence of MCPyV in a large sample and to correlate the results with the clinical course of the disease. 59 samples from 44 patients were analysed for the presence of MCPyV using the primers LT3, VP1 and LT1. The clinical records of these patients were evaluated and correlated with the presence of MCPyV. 58% of specimens were positive for MCPyV. Of these, LT3 was positive in 53%, VP1 in 37% and LT1 in 10%. 57% of primary tumours and 53% of metastases were positive for LT3; the numbers for VP1 and LT1 were lower. There was no correlation between the detection of MCPyV in the primary tumour and the appearance of metastases. The survival time was statistically independent from the presence of MCPyV. There is a striking occurrence of MCPyV in MCC, but whether it affects the clinical course remains unclear.

Vascular invasion is an early event in pathogenesis of Merkel cell carcinoma

This study investigated vascular and especially lymphovascular invasion in primary Merkel cell carcinoma and its value as a prognostic factor. Paraffin-embedded blocks prepared from tumor samples obtained from 126 patients diagnosed with Merkel cell carcinoma in 1979-2004 were immunohistochemically stained using antibodies CD31 and D2-40 to detect intravascular tumor emboli. This finding was compared with the clinical data and the disease outcome. Intravascular tumor cells were observed in 117 (93%) of the samples. The majority, 83 (66%), showed only lymphovascular invasion. Only blood vascular invasion was seen in four (3%) samples. In all, 30 (24%) samples demonstrated both lymphovascular invasion and blood vascular invasion. In only nine (7%) samples, there was no invasion within the vascular structures. The tumors lacking invasion were significantly smaller (P<0.01 and alpha=0.050) than those with vascular invasion, although lymphovascular invasion was observed even in the smallest tumor (0.3 cm) of this study. Already in the early stages of the disease, Merkel cell carcinoma seems to have the capacity to penetrate vessel walls. Our finding of the high frequency of lymphovascular invasion might therefore explain the extremely aggressive clinical behavior of Merkel cell carcinoma. This may support the role of sentinel node biopsy even in the case of very small primary Merkel cell carcinoma tumors.

Updated Review of the Pathogenesis and Management of Merkel Cell Carcinoma

Background:

Merkel cell carcinoma is a rare, aggressive, malignant cutaneous tumor of the elderly or immunosuppressed individuals that usually appears on sun-exposed areas of the body. Its pathogenesis is still debated, and, currently, no standardized treatment exists.

Objective:

To provide a current updated review of the most relevant data concerning the pathogenesis and management of Merkel cell carcinoma.

Methods:

Using relevant MeSH terms, we performed a review of the literature on these subjects from 1980 to June 2009.

Results and Conclusion:

The current management of Merkel cell carcinoma is based on surgical excision as the majority of patients present with localized disease, whereas up to 30% have regional lymph node metastases. In these cases, the best outcome is achieved with multidisciplinary management that includes radiotherapy. Chemotherapy is part of the treatment in advanced cases and is mandatory for distant metastatis. Given that a recent work showed the presence of a previously unknown polyomavirus, which the authors called Merkel cell polyomavirus, the therapeutical approach to Merkel cell carcinoma could be reconsidered in the future.

Effect of radiotherapy dose and volume on relapse in Merkel cell cancer of the skin

PURPOSE

To assess the effect of radiotherapy (RT) dose and volume on relapse patterns in patients with Stage I-III Merkel cell carcinoma (MCC).

PATIENTS AND METHODS

This was a retrospective analysis of 112 patients diagnosed with MCC between January 2000 and December 2005 and treated with curative-intent RT.

RESULTS

Of the 112 evaluable patients, 88% had RT to the site of primary disease for gross (11%) or subclinical (78%) disease. Eighty-nine percent of patients had RT to the regional lymph nodes; in most cases (71%) this was for subclinical disease in the adjuvant or elective setting, whereas 21 patients (19%) were treated with RT to gross nodal disease. With a median follow-up of 3.7 years, the 2-year and 5-year overall survival rates were 72% and 53%, respectively, and the 2-year locoregional control rate was 75%. The in-field relapse rate was 3% for primary disease, and relapse was significantly lower for patients receiving >or=50 Gy (hazard ratio [HR] = 0.22; 95% confidence interval [CI], 0.06-0.86). Surgical margins did not affect the local relapse rate. The in-field relapse rate was 11% for RT to the nodes, with dose being significant for nodal gross disease (HR = 0.24; 95% CI, 0.07-0.87). Patients who did not receive elective nodal RT had a much higher rate of nodal relapse compared with those who did (HR = 6.03; 95% CI, 1.34-27.10).

CONCLUSION

This study indicates a dose-response for subclinical and gross MCC. Doses of >or=50 Gy for subclinical disease and >or=55 Gy for gross disease should be considered. The draining nodal basin should be treated in all patients.

Malignant skin neoplasms

Skin cancers may be derived from any part of the skin, and the classification of all variants is extensive. Overall they are the most common cancers of the body, and include those that are highly mortal and those that are associated with an increased morbidity. In this review the most common skin cancers confronted by the clinician and their management are discussed. New associations are highlighted, as well as new information that can help the clinician to better understand the pathogenesis of many of these entities.

Metastatic Merkel cell carcinoma with positive expression of thyroid transcription factor-1--a case report

We report on a case of metastatic Merkel cell carcinoma in a 74-year-old patient with positive staining for thyroid transcription factor-1. This represents a new immunohistochemical staining pattern for Merkel cell carcinoma and has implications regarding the accurate diagnosis of this tumor type.

Diagnostic imaging in Merkel cell carcinoma: lessons to learn from 16 cases with correlation of sonography, CT, MRI and PET

OBJECTIVE

The authors report imaging findings in a series of 16 patients with MCC, a rare tumour which is often managed primarily by a dermatologist. To our knowledge, no equivalent series of MCC has been described in the nuclear medicine literature.

MATERIAL AND METHODS

In this IRB-approved retrospective noncomparative case series 16 patients with biopsy-proven Merkel cell carcinoma were included between January 1999 and October 2007. Twenty-nine whole body PET scans (18F-FDG n=24, 18F-FDOPA n=5) in 16 patients were retrospectively reviewed with regard to tracer uptake in six anatomical sites per patient. For 127/144 of FDG-PET evaluated regions and 68/144 of regions depicted by conventional imaging methods, a valid standard of reference could be obtained. A combined standard of reference was applied, which consisted of histopathology (lymphadenectomy or biopsy) or clinical or radiological follow-up for at least 12 months.

RESULTS

the mean FDG uptake over the clinicopatholigical verified FDG avid areas was 4.7 SUV (1.5-9.9 SUV). The region based assessment of diagnostic value, in consideration of the standard of reference, resulted in a sensitivity of 85.7% and a specificity of 96.2% of FDG-PET (n=127) and in a combined sensitivity of 95.5% and a specificity of 89.1% for morphological imaging methods (n=68). Differences between methods did not reach statistical significance (p=1.00, p=0.18).

CONCLUSIONS

FDG-PET is a highly useful whole body staging method of comparable value compared to conventional imaging methods with restricted field of view. The lessons learned from case series are discussed.