Merkel cell carcinoma

A practical update of surgical management of merkel cell carcinoma of the skin

The role of surgeons in the treatment of Merkel cell carcinoma (MCC) of the skin is reviewed, with respect to diagnosis and treatment. Most of the data in the literature are case reports. Surgery is the mainstay of treatment. A wide local excision, with sentinel node (SLN) biopsy, is the recommended treatment of choice. If SLN is involved, nodal dissection should be performed; unless patient is unfit, then regional radiotherapy can be given. Surgeons should always refer patients for assessment of the need for adjuvant treatments. Adjuvant radiotherapy is well tolerated and effective to minimize recurrence. Adjuvant chemotherapy may be considered for selected node-positive patients, as per National Comprehensive Cancer Network guideline. Data are insufficient to assess whether adjuvant chemotherapy improves survival. Recurrent disease should be treated by complete surgical resection if possible, followed by radiotherapy and possibly chemotherapy. Generally results of multimodality treatment for recurrent disease are better than lesser treatments. Future research should focus on newer chemotherapy and molecular targeted agents in the adjuvant setting and for gross disease.

The Merkel cell carcinoma challenge: a review from the fine needle aspiration service

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin that occurs primarily in elderly or immunocompromised patients. For this report, the authors reviewed the diagnostic challenges associated with MCC encountered on their fine-needle aspiration (FNA) service and also conducted an in-depth review of the literature on MCC. A computer search for patients who were diagnosed with MCC by FNA at the authors' institution from 2006 to 2010 was conducted, and 5 patients were selected for cytologic and immunochemical analyses based on their varied and diagnostically challenging clinical presentations. The 5 selected patients had clinical findings commonly associated with MCC, including advanced age (4 of the 5 patients were ages 75-85 years) and a history of previous malignancies (3 of the 5 patients had a history of previous malignancy), and 1 patient was diagnosed with a concomitant low-grade lymphoma. The patients and their disease illustrated the protean clinical presentation of MCC and the clinical and cytologic challenges associated with this neoplasm. The current findings indicate the need for cytopathologists to be aware of the deceptive presentation of this neoplasm and its cytologic and immunochemical features to correctly diagnose this insidious neoplasm.

Merkel cell carcinoma: a retrospective study on 48 cases and review of literature

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin. Fourty-eight patients with MCC were observed at the Rare Hormonal Tumors Group of Cremona Hospital, 15 of these with unknown primary site. Due to rarity of Merkel cell carcinoma, clinical experience is generally limited. Data from our series confirm the current recommendations. Wide surgical excision must be associated with radiotherapy also in early stages in order to avoid local relapse and the rapid progression of disease. In advanced stages chemotherapy is the standard despite the short duration of responses and poor quality of life. The data of our series, characterized by a high demand for second opinion, offer some insight about the real rarity of the tumor, the difficulty of managing of disease in our country secondary to a wrong cultural approach to the problem, the indiscriminate use of molecules unnecessary and often expensive, the lack of protocols, and the presence of guidelines often ignored. This results in very poor survival associated with a very low quality of life, requiring to find the right direction towards a correct management of disease.

Recent advances in the understanding of the genetics, etiology, and treatment of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a highly aggressive skin malignancy. The growing incidence and recognition of this cancer in elderly or immunosuppressed individuals suggests that it is becoming an increasing clinical challenge. MCC recently has been demonstrated to have a probable viral pathogenesis related to a novel member of the polyomavirus (termed Merkel cell polyomavirus [MCV]). The molecular pathogenesis of viral carcinogenesis is currently being worked out in MCC. Current diagnostic and therapeutic strategies are discussed, with an eye toward the future development of molecularly targeted treatments.

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 of the genitourinary tract

Merkel cell carcinomas are rare cutaneous neoplasms that are known to metastasize to various mucosal sites, including the genitourinary tract. Primary Merkel cell carcinomas of the genitourinary tract are extremely rare and may be mistaken for other more common carcinomas of the genitourinary tract, including urothelial carcinomas and prostatic carcinomas. However, primary Merkel cell carcinoma of the genitourinary tract is a very aggressive tumor with poor prognosis. Accurate diagnosis is crucial for appropriate clinical treatment. The discovery of the Merkel cell polyomavirus as a possible causative agent adds a new dimension in the understanding of the pathogenesis and diagnosis, and possible targeted therapies for this tumor.

Expression of stem cell markers nestin and cytokeratin 15 and 19 in cutaneous malignancies

BACKGROUND

Emerging evidence is implicating stem cells in the pathogenesis of different cutaneous neoplasms. The immunohistochemical use of stem cell markers has facilitated stem cell identification. While few studies have examined the expression of cytokertatin (CK)15 and cytokeratin (CK)19 in basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), only rarely have nestin expression been examined in these two malignancies. Furthermore, stem cell marker expression, to the best of our knowledge, has not been examined in Merkel cell carcinoma (MCC).

METHODS

In this study, we examined the expression of stem cell markers CK15, CK19 and nestin in 51 overall cases (11 cases of MCC and 20 cases each of BCC and SCC) retrieved from the pathology files of Skin Pathology Laboratory, Boston University School of Medicine.

RESULTS

Cytokeratin 15 immunoreactivity was observed in 30% of BCC cases and only a single (5%) SCC case, while all MCC cases were negative. While 60% of BCC cases and 30% of SCC cases stained positively with CK19, all MCC cases showed positive immunostaining in a dot-like pattern. While negative in BCC and MCC, nestin expression was interestingly seen in 45% of SCC cases.

CONCLUSIONS

Our study described the expression profiles of stem cell markers CK15, CK19 and nestin in BCC, SCC and MCC. In addition to confirming results of the previous reports, our study also showed positive nestin expression in around half of SCC cases, which adds this malignancy to the cutaneous tumours that have been so far reported to exhibit nestin expression.

Merkel cell carcinoma: correlation of KIT expression with survival and evaluation of KIT gene mutational status

Merkel cell carcinoma is one of the most aggressive primary cutaneous malignancies. Because some Merkel cell carcinomas express the receptor tyrosine kinase KIT, we aimed to evaluate the correlation of KIT expression with the outcome and the presence of activating mutations in the KIT gene in Merkel cell carcinoma. A total of 49 tumors from 40 patients with a diagnosis of Merkel cell carcinoma were identified, of which 30 cases from 21 patients were used in the study. KIT expression was assessed by immunohistochemistry on formalin-fixed, paraffin-embedded material. Cases were divided into low expressors (0-1+ staining intensity) and high expressors (2-3+ staining intensity). Direct sequencing of exons 9, 11, 13, 17, and 18 of the KIT gene spanning the extracellular, juxtamembrane, and tyrosine kinase domains was performed for cases with high KIT expression. Thirty tumors from 21 patients were analyzed for KIT expression. High KIT expression was seen in 67% of the patients. Five-year survival rates in tumors expressing high versus low levels of KIT were 0% versus 57.8%, respectively; however, this dramatic difference did not reach statistical significance (P = .07). A total of 4 point mutations were identified in 18 tumors analyzed. Two of these were silent mutations involving exons 17 and 18, and 2 involved intron 16-17. Two of the identified mutations may represent novel polymorphisms. Our work suggests a correlation between KIT expression and a worse prognosis in Merkel cell carcinoma patients, raising the possibility of an active role of this receptor in tumor progression and metastasis. However, we did not identify KIT activating mutations in any of the tumors analyzed.

Merkel cell carcinoma of the hand: case report and literature review

We are reporting on a 72-year-old male who was diagnosed with Merkel cell carcinoma on the dorsal aspect of his left index finger. This rare highly aggressive malignancy of the skin has only exceptionally been described on the finger or hand. This case report helps review important findings associated with this rare malignancy and reviews the pertinent literature.

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.

Expression of the embryonic stem cell transcription factor SOX2 in human skin: relevance to melanocyte and merkel cell biology

SOX2 is a gene located on chromosome 3q26.33 that encodes a transcription factor important to maintenance of embryonic neural crest stem cell pluripotency. We have identified rare SOX2-immunoreactive cells in normal human skin at or near the established stem cell niches. Three subsets of SOX2-positive cells were defined in these regions: those expressing only SOX2 and those that co-expressed SOX2 and either CK20 or microphthalmia-associated transcription factor, which are consistent with dichotomous differentiation of SOX2-expressing precursors along neuroendocrine (Merkel cell) or melanocytic lines, respectively. Examination of Merkel cell carcinomas confirmed nuclear SOX2 expression in this tumor type. In human patient melanoma, strong nuclear expression of SOX2 was noted in a subset of tumors, and the ability to detect SOX2 in lesional cells significantly correlated with primary tumor thickness in a survey cohort. To assess the potential role of SOX2 in melanoma growth, an in vivo tumorigenesis assay was used. Whereas SOX2 knockdown failed to influence proliferation of cultured melanoma cells in vitro, tumor xenografts generated with the SOX2-knockdown cell line showed significant decrease in mean tumor volume as compared with controls. In aggregate, these findings suggest that SOX2 is a novel biomarker for subpopulations of normal skin cells that reside in established stem cell niches and that might relate to Merkel cell and melanocyte ontogeny and tumorigenesis.

Nonmelanoma skin cancer

This article provides readers with a comprehensive review of the evaluation and management of nonmelanoma skin cancers. Treatment recommendations are heavily based on the most recent guidelines from the National Comprehensive Cancer Network. Merkel cell carcinoma and dermatofibrosarcoma protuberans are also discussed. After reviewing this article, readers should be equipped with a better understanding of these entities and the current recommendations for their management.

Intraepidermal and dermal Merkel cell carcinoma with squamous cell carcinoma in situ: a case report with review of literature

Merkel cell carcinoma (MCC), a rare aggressive primary cutaneous neuroendocrine carcinoma, occurs on sun-damaged skin, especially in the elderly. Its unique co-expression of cytokeratin 20 (CK20) and neuroendocrine markers, including neuron-specific enolase (NSE), is diagnostic. Most MCCs are located in the dermis, rarely has an intraepidermal component been reported. We report a case of MCC with an intraepidermal component admixed with squamous cell carcinoma in situ (SCCIS). We were able to identify the differences in the immunohistochemical expression pattern between that of the intraepidermal and the dermal components. Most intraepidermal neoplastic cells of MCC in this case showed a less intense immunoreactivity to CK20 and NSE compared to that of dermal neoplastic cells. This case reports an unusual occurrence of combined SCC and MCC that shows both intraepidermal and dermal components.

Clinical factors associated with Merkel cell polyomavirus infection in Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma is a rare malignancy of the skin. Integration of Merkel cell polyomavirus (MCPyV) DNA to the tumor genome is frequent in these cancers. The clinical consequences of MCPyV infection are unknown.

METHODS

We analyzed formalin-fixed paraffin-embedded Merkel cell carcinoma tissue samples from 114 of 207 patients diagnosed with Merkel cell carcinoma in Finland from 1979 to 2004 for the presence of MCPyV DNA with the use of polymerase chain reaction (PCR), quantitative PCR, and DNA sequencing and examined associations between tumor MCPyV DNA status and histopathologic factors and survival. The median follow-up time after Merkel cell carcinoma diagnosis for subjects who were alive was 9.9 years (range = 4.9-21.9 years). All P values are two-sided.

RESULTS

MCPyV DNA was present in 91 carcinomas (79.8%). Compared with MCPyV DNA-negative cancers, MCPyV DNA-positive cancers were more often located in a limb (40.7% vs 8.7%, P = .015) and less frequent in patients who had regional nodal metastases at diagnosis (6.6% vs 21.7%, P = .043). Patients with MCPyV DNA-positive tumors had better overall survival than those with MCPyV DNA-negative tumors (5-year survival: 45.0% vs 13.0%, respectively; P < .001, two-sided log-rank test).

CONCLUSIONS

MCPyV infection is associated with clinical outcomes in patients with Merkel cell carcinoma. These findings lend support to the hypothesis that viral infection is frequently associated with the pathogenesis of Merkel cell carcinoma.

Factors influencing relapse-free survival in Merkel cell carcinoma of the lower limb--a review of 60 cases

PURPOSE

Factors affecting relapse-free survival (RFS) in patients with Merkel cell carcinoma (MCC) of the lower limb were reviewed.

METHODS AND MATERIALS

The records of 60 patients from 1986 to 2005 with a diagnosis of MCC of the lower limb or buttock were retrospectively reviewed. The patients were treated with curative intent with surgery, radiation, or chemotherapy.

RESULTS

The 5-year overall survival, disease-specific survival, and RFS were 53%, 61%, and 20%, respectively. Factors influencing RFS were analyzed using univariate analysis. It appeared that recurrent disease worsened RFS (p = 0.03) and the addition of any radiotherapy improved RFS (p <0.001), as did radiotherapy to the inguinal nodes (p = 0.01) or primary site and inguinal nodes (p = 0.003). Age, surgical margins, and stage were not statistically significant. On multivariate analysis, the only significant factor was the addition of radiotherapy (hazard ratio = 0.51 p = 0.03).

CONCLUSION

The addition of radiotherapy improves RFS compared with surgery alone. Elective treatment should be given to the inguinal nodes to reduce the risk of relapse.

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.

A comprehensive review of the treatment of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an uncommon but malignant cutaneous neuroendocrine carcinoma with a high incidence of local recurrence, regional lymph node metastases, and subsequent distant metastases. The etiology of MCC remains unknown. It usually occurs in sun-exposed areas in elderly people, many of whom have a history of other synchronous or metachronous sun-associated skin lesions. The outcome for most patients with MCC is generally poor. Surgery is the mainstay of treatment. The role of adjuvant therapy has been debated. However, data from recent development support a multimodality approach, including surgical excision of primary tumor with adequate margins and sentinel lymph node dissection followed by postoperative radiotherapy in most cases, as current choice of practice with better locoregional control and disease-free survival. Patients with regional nodal involvement or advanced disease should undergo nodal dissection followed by adjuvant radiotherapy and, perhaps, systemic platinum-based chemotherapy in most cases.

Neuroendocrine (Merkel cell) carcinoma of the retroperitoneum with no identifiable primary site

BACKGROUND

Neuroendocrine carcinoma is an aggressive neoplasm that mainly affects elderly Caucasians and typically arises in sun-exposed areas of the skin. The disease is rather rare and only a relatively few cases present with no apparent primary lesion.

CASE PRESENTATION

We report a case of an 81-year-old Caucasian male with neuroendocrine carcinoma, which initially presented as a large retroperitoneal mass. Pathological and immunohistochemical analysis of the transabdominal CT-guided biopsy specimen revealed tissue consistent with neuroendocrine carcinoma. The patient underwent exploratory laparotomy and the mass was successfully excised along with an associated mesenteric lymph node.

DISCUSSION

There are currently two possible explanations for what occurred in our patient. First, the retroperitoneal mass could be a massively enlarged lymph node where precursor cells became neoplastic. This would be consistent with a presumptive diagnosis of primary nodal disease. Alternatively, an initial skin lesion could have spontaneously regressed and the retroperitoneal mass represents a single site of metastasis. Since Merkel cell precursors have never been identified within lymph nodes, the latter theory seems more befitting. Moreover, metastasis to the retroperitoneal lymph nodes has been reported as relatively common when compared to other sites such as liver, bone, brain and skin.

CONCLUSION

Wide local excision of the primary tumor is the surgical treatment of choice for localized disease. We propose that further studies are needed to elucidate the true efficacy of chemotherapy in conventional as well as unconventional patients with neuroendocrine carcinoma.

Merkel cell carcinoma frequently shows histologic features of basal cell carcinoma: a study of 30 cases

BACKGROUND

Merkel cell carcinoma (MCC) is a basaloid cutaneous neoplasm that may be mistaken for basal cell carcinoma (BCC).

METHODS

Thirty MCCs were examined for areas that histologically resembled BCC.

RESULTS

One of the histologic features of BCC (either a mucinous stroma or stromal artifactual retraction) was identified in all MCCs. A mucinous stroma was found in 28 MCCs (93%), stromal artifactual retraction in 27 (90%), mucin-containing gland-like spaces within tumor nests in 8 (27%), focal peripheral palisading in 8 (27%), epidermal involvement in 3 (10%) and dystrophic calcification in 1 MCC (3%). The cytologic features and absence of widespread peripheral palisading were the most reliable discriminators between MCC and BCC on routine sections. Squamous cell carcinoma was identified in four cases (13%). Two cases (7%) contained pagetoid intraepidermal spread (IES) of MCC. In one case, there was IES over the entire epidermal surface associated with intranuclear clearing, resembling the intranuclear cytoplasmic inclusions (INI) common in melanocytic tumors. INI were identified in six MCCs (20%).

CONCLUSIONS

MCCs frequently contain areas that histologically resemble BCC and other more common cutaneous malignancies. This can lead to diagnostic errors, particularly in small fragmented curettage specimens or frozen sections.

Merkel cell carcinoma: critical review with guidelines for multidisciplinary management

Merkel cell carcinoma (MCC) is a relatively rare cutaneous malignancy that occurs predominantly in the older white population. The incidence of MCC appears to have tripled during the past 20 years; an increase that is likely to continue because of the growing number of older Americans. The pathogenesis of MCC remains largely unknown. However, ultraviolet radiation and immunosuppression are likely to play a significant pathogenetic role. Many questions currently remain unanswered regarding the biologic behavior and optimal treatment of MCC. Large, prospective, randomized studies are not available and are unlikely to be performed because of the rarity of the disease. The objective of this review was to provide a comprehensive reference for MCC based on a critical evaluation of the current data. The authors investigated the importance of sentinel lymph node biopsy as a staging tool for MCC to assess the status of the regional lymph node basin and to determine the need for additional therapy to the lymph node basin. In an attempt to standardize prospective data collection with the intention to define prognostic indicators, the authors also present histopathologic profiles for primary MCC and sentinel lymph nodes. The controversies regarding the appropriate surgical approach to primary MCC, the use of adjuvant radiation therapy, and the effectiveness of adjuvant chemotherapy were examined critically. Finally, the authors have provided treatment guidelines based on the available evidence and their multidisciplinary experience.

Merkel cells

Merkel cells are post-mitotic cells scattered throughout the epidermis of vertebrates. They are particularly interesting because of the close connections that they develop with sensory nerve endings and the number of peptides they can secrete. These features suggest that they may make an important contribution to skin homeostasis and cutaneous nerve development. However, these cells remain mysterious because they are difficult to study. They have not been successfully cultured and cannot be isolated, severely hampering molecular biology and functional analysis. Merkel cells probably originate in the neural crest of avians and mammalians, and their "spontaneous" appearance in the epidermis may be caused by a neuron-independent epidermal differentiation process. Their functions are still unclear: they take part in mechanoreception or at least interact with neurons, but little is known about their interactions with other epidermal cells. This review provides a new look at these least-known cells of the skin. The numerous peptides they synthesize and release may allow them to communicate with many cells other than neurons, and it is plausible that Merkel cells play a key role in skin physiology and physiopathology.

Merkel Cell Carcinoma: Assessing the Effect of Wide Local Excision, Lymph Node Dissection, and Radiotherapy on Recurrence and Survival in Early-Stage Disease—Results From a Review of 82 Consecutive Cases Diagnosed Between 1992 and 2004

BACKGROUND

Wide surgical excision, lymph node dissection, and radiotherapy have been used with varying efficacy in the management of early-stage Merkel cell carcinoma.

METHODS

Records of 82 patients with early-stage Merkel cell carcinoma between 1992 and 2004 were reviewed.

RESULTS

Forty-two patients developed a recurrence, and 44 died during the study period. Twenty-nine patients presented with regional lymph node disease, which was independently associated with diminished survival (hazard ratio [HR], 4.08; 95% confidence interval [CI], 1.55-10.75; P = .005). Lymphadenectomy was independently associated with prolonged disease-free survival (median, 28.5 vs. 11.8 months; HR, .46; 95% CI, .22-.94; P = .034) but not overall survival (P = .25). Margin-negative excision of the primary tumor (60 of 73) was not significantly associated with either prolonged disease-free survival (median, 16 vs. 14 months) or overall survival (median, 54 vs. 34 months). Forty-eight patients received radiotherapy: 36 to the primary site and 31 to the regional lymph nodes. Radiotherapy to both sites was associated with a longer median time to first recurrence (primary site, 24.2 vs. 11.8 months; regional lymph nodes, 46.2 vs. 11.3 months) and survival (primary site, 53.9 vs. 45.7 months; regional lymph nodes, 103.1 vs. 34.2 months). Administration of any radiotherapy was significantly associated with a prolonged time to first recurrence (HR, .39; 95% CI, .20-.75; P = .004) and survival (HR, .39; 95% CI, .18-.82; P = .013) on the Cox regression multivariate analyses.

CONCLUSIONS

Adjuvant radiotherapy to the primary site after surgical excision is recommended in early-stage disease. Involved regional lymph nodes should be treated with radiotherapy with or without lymphadenectomy.

Epidemiology of non-gastroenteropancreatic (neuro)endocrine tumours

The widespread availability and reliability of immunohistochemical techniques in the last three decades have allowed researchers to identify cells with common neuroendocrine markers in virtually every organ. As a whole, these neuroendocrine cells form the so-called diffuse neuroendocrine system. Tumours arising from the cells of the diffuse neuroendocrine system are defined as (neuro)endocrine tumours (NETs). NETs have been increasingly described in recent years. However, despite the increase in the number of published papers focused on NET, we still lack adequate epidemiological data, particularly for non-gastroenteropancreatic (GEP) NETs. Furthermore, the real incidence of neuroendocrine differentiation for most sites is not completely known and is probably underestimated. As a consequence, data on the clinical features of many NET subgroups are not well known or confusing. For all of these reasons, we have attempted to evaluate the epidemiology of non-GEP NETs, reviewing the limited data available in the literature.

Merkel cell cancer of the skin

Merkel cell carcinoma (MCC) is a rare malignant cutaneous tumor of the elderly with rapidly growing skin nodules found predominantly on sun-exposed areas of the body. The vast majority of patients present with localized disease, while up to 30% have regional lymph node metastases. Despite local excision and the incidence of local recurrence, regional lymph node metastases and distant metastases is high and usually occurs within 2 years of primary diagnosis. The optimal treatment for patients with MCC remains unclear. The best outcome is achieved with multidisciplinary management including surgical excision of primary tumor with adequate margins and post-operative radiotherapy (RT) to control local and regional disease. Patients with regional nodal metastases should be treated with lymph node dissection plus RT. Adjuvant chemotherapy (CT) should be considered as part of the initial management. In case of metastatic disease CT based on regimens used for small-cell lung cancer is the standard treatment of care.

Merkel cell carcinoma

Background

Merkel cell carcinoma (MCC) is an unusual primary neuroendocrine carcinoma of the skin. MCC is a fatal disease, and patients have a poor chance of survival. Moreover, MCC lacks distinguishing clinical features, and thus by the time the diagnosis is made, the tumour usually have metastasized. MCC mainly affects sun-exposed areas of elderly persons. Half of the tumours are located in the head and neck region.

Methods

MCC was first described in 1972. Since then, most of the cases reported, have been in small series of patients. Most of the reports concern single cases or epidemiological studies. The present study reviews the world literature on MCC. The purpose of this article is to shed light on this unknown neuroendocrine carcinoma and provide the latest information on prognostic markers and treatment options.

Results

The epidemiological studies have revealed that large tumour size, male sex, truncal site, nodal/distant disease at presentation, and duration of disease before presentation, are poor prognostic factors. The recommended initial treatment is extensive local excision. Adjuvant radiation therapy has recently been shown to improve survival. Thus far, no chemotherapy protocol have achieved the same objective.

Conclusion

Although rare, the fatality of this malignancy makes is important to understand the etiology and pathophysiology. During the last few years, the research on MCC has produced prognostic markers, which can be translated into clinical patient care.

Combined Merkel Cell Carcinoma and Atypical Fibroxanthoma

BACKGROUND

Although there are reports of squamous cell carcinoma arising within and adjacent to Merkel cell carcinoma, and one report of an atypical fibroxanthoma-like tumor arising in an irradiated recurrent Merkel cell carcinoma, there have previously been no reports of an immunohistochemically verified atypical fibroxanthoma occurring in conjunction with a Merkel cell carcinoma.

OBJECTIVE

We report on a neoplasm with distinct features of both Merkel cell carcinoma and atypical fibroxanthoma.

METHODS

Histologic and immunohistochemical evaluations were performed.

RESULTS

Our results verify the finding of a combined Merkel cell carcinoma and atypical fibroxanthoma.

CONCLUSION

This case is an interesting and unusual combination of tumors. The origin of the Merkel cell carcinoma is revisited. Debated origins include neuroendocrine, epithelial, and pleuripotent stem cell.

Pancreatic metastasis of Merkel cell carcinoma and concomitant insulinoma: case report and literature review

Background

Merkel cell carcinomas are rare neoplasm of neuroendocrine origin, usually observed in elderly people in areas with abundant sunlight, and predominantly located on the head and neck, extremities, and trunk. In many patients, a local recurrence after resection of the primary tumour and even distant metastases can be found.

Case presentation

We report an unusual occurrence of pancreatic metastases from a previously diagnosed Merkel cell carcinoma with the discovery of a concomitant insulinoma. An 82-year old lady suffered from recurrent attacks of hypoglycemia and presented with an abdominal mass, 2 years prior she had an excision done on her eyebrow that was reported as Merkel cell carcinoma. An extended distal pancreatectomy and splenectomy along with resection of the left flexure of the colon for her abdominal mass was carried out. Final histopathology of the mass was a poorly differentiated endocrine carcinoma in the pancreatic tail, in the peripancreatic tissue and in the surrounding soft tissue consistent with metastatic Merkel cell carcinoma in addition to an insulinoma of the pancreatic body.

Conclusion

This is the first documented case of a metastatic Merkel cell carcinoma and a concomitant insulinoma, suggesting either a mere coincidence or an unknown neuroendocrine tumor syndrome.

Does chemotherapy improve survival in high-risk stage I and II Merkel cell carcinoma of the skin?

PURPOSE

The effectiveness of synchronous carboplatin, etoposide, and radiation therapy in improving survival was evaluated by comparison of a matched set of historic control subjects with patients treated in a prospective Phase II study that used synchronous chemotherapy and radiation and adjuvant chemotherapy.

PATIENTS AND METHODS

Patients were included in the analysis if they had disease localized to the primary site and nodes, and they were required to have at least one of the following high-risk features: recurrence after initial therapy, involved nodes, primary size greater than 1 cm, or gross residual disease after surgery. All patients who received chemotherapy were treated in a standardized fashion as part of a Phase II study (Trans-Tasman Radiation Oncology Group TROG 96:07) from 1997 to 2001. Radiation was delivered to the primary site and nodes to a dose of 50 Gy in 25 fractions over 5 weeks, and synchronous carboplatin (AUC 4.5) and etoposide, 80 mg/m(2) i.v. on Days 1 to 3, were given in Weeks 1, 4, 7, and 10. The historic group represents a single institution's experience from 1988 to 1996 and was treated with surgery and radiation alone, and patients were included if they fulfilled the eligibility criteria of TROG 96:07. Patients with occult cutaneous disease were not included for the purpose of this analysis. Because of imbalances in the prognostic variables between the two treatment groups, comparisons were made by application of Cox's proportional hazard modeling. Overall survival, disease-specific survival, locoregional control, and distant control were used as endpoints for the study.

RESULTS

Of the 102 patients who had high-risk Stage I and II disease, 40 were treated with chemotherapy (TROG 96:07) and 62 were treated without chemotherapy (historic control subjects). When Cox's proportional hazards modeling was applied, the only significant factors for overall survival were recurrent disease, age, and the presence of residual disease. For disease-specific survival, recurrent disease was the only significant factor. Primary site on the lower limb had an adverse effect on locoregional control. For distant control, the only significant factor was residual disease.

CONCLUSIONS

The multivariate analysis suggests chemotherapy has no effect on survival, but because of the wide confidence limits, a chemotherapy effect cannot be excluded. A study of this size is inadequately powered to detect small improvements in survival, and a larger randomized study remains the only way to truly confirm whether chemotherapy improves the results in high-risk MCC.

A case report of Merkel cell carcinoma on chronic lymphocytic leukemia: differential diagnosis of coexisting lymphadenopathy and indications for early aggressive treatment

BACKGROUND

Chronic lymphocytic leukemia (CLL) is a monoclonal disorder, characterized by a progressive proliferation of functionally incompetent B lymphocytes. There is increased evidence of association between CLL and skin cancers, including the uncommon Merkel cell carcinoma (MCC).

CASE PRESENTATION

A case report of an 84-year old male, who presented with an aggressively recurrent form of MCC on the lower lip, on the background of an 8-year history of untreated CLL. During the recurrences of MCC, coexisting regional lymphadenopathy, posed a problem in the differential diagnosis and treatment of lymph node involvement. Histopathology and immunoistochemistry showed that submandibular lymphadenopathy coexisting with the second recurrence of MCC, was due to B-cell small lymphocytic lymphoma. The subsequent and more aggressive recurrence of the skin tumor had involved the superficial and deep cervical lymph nodes. Surgical excision followed by involved field radiation therapy has been proven effective for both malignancies.

CONCLUSION

MCC has a high incidence of regional lymphadenopathy at presentation (12-45%) and even when it arises on the background of chronic leukemia, lymphadenopathy at presentation should be managed agressively with elective lymph node dissection. We overview the postulated correlation between Merkel tumor and CCL, the differential diagnosis of regional lymphadenopathy during the recurrences of the skin tumor and the strategies of treatment.

Merkel cell carcinoma of skin: diagnosis and management strategies

Merkel cell carcinoma (MCC) of the skin is a rare form of cutaneous malignancy of neuroendocrine origin with a propensity to affect predominately elderly patients in sun-exposed areas. The tumour has an extremely aggressive growth pattern with the potential to seed into the dermal lymphatics at an early stage as well as spread to nodes and distant sites. Successful outcomes can be achieved with early diagnosis and a multidisciplinary approach to management. Patients with MCC should be carefully staged to exclude distant metastatic disease. Treatment should be approached with both the primary site and the lymph nodes in mind. The primary site should be excised with clear margins, followed by postoperative radiotherapy to the primary site and affected nodes. Addition of chemotherapy to patients perceived to be at high-risk of distant recurrence (e.g. those with involved nodes) has been considered, but evidence supporting this approach is relatively scant. This treatment strategy needs to be approached with caution in the elderly because of the risk of myelosuppression. An aggressive treatment approach is warranted at the first attempt to treat MCC as treatment for recurrent disease is less likely to be successful.

Carcinoma de células de Merkel. Estudio de cinco casos

Merkel cell carcinoma (MCC) is a rare malignant skin tumor of neuroendocrine origin with a poor prognosis and rapid progression. It is usually an erythematous nodule on the face, and is associated with other skin neoplasms. Its histology shows a large mass of small cells containing oval nuclei with powdery chromatin in the dermis. These cells are positive for neurospecific enolase, chromogranin, synaptophysin and cytokeratins AE1/AE3. We present five patients (3 males and 2 females, aged 58 to 89 years) seen at our hospital in the last three years for MCC. Their treatment and evolution were tracked, and many of the aspects indicated were seen. MCC must be kept in mind in the differential diagnosis, as early detection along with aggressive treatment significantly improve the patients survival rate. Close follow up is necessary because of the high recurrence rates. The development of a response protocol in order to better manage this disease would be desirable.

Merkel cell carcinoma in situ

BACKGROUND

Merkel cell carcinoma (MCC) is a dermal small blue-cell tumor that occurs in the elderly on the sun damaged head and neck. Epidermal involvement is unusual and MCC limited to the epidermis is very rare.

CASE REPORT

A slightly tender pink hyperkeratotic papule was noted on the dorsal right hand of a 76-year-old man with a history of multiple skin cancers. An intraepidermal proliferation of small blue cells distributed in nests and single units at all levels of the epidermis was found within a solar keratosis and adjacent to an area of squamous cell carcinoma in situ. Cytokeratin 20 and neuron specific enolase highlighted these cells and failed to reveal dermal involvement. There was no residue on re-excision.

CONCLUSION

We report the third case of MCC in situ. These lesions have only been reported in association with squamous neoplasms on the extremities.

Treatment of Recurrent Merkel Cell Carcinoma: An Analysis of 46 Cases

This report describes the course of recurrent Merkel cell carcinoma and defines possible treatment strategies for recurrent disease as seen in a long-term multisite retrospective analysis. Merkel cell carcinoma is a highly aggressive neuroendocrine skin cancer. Surgery and radiation therapy have been demonstrated ability to control this disease; however, recurrence is common. Systemic chemotherapy has, as yet, no presently defined role in primary treatment, and few conclusions can be reached regarding optimal treatment of disease recurrence. Forty-six patients were identified over the last 15 years in a retrospective analysis of patient records from several hospitals in the San Antonio, TX area. Hospital charts as well as outpatient treatment records were reviewed. Almost all patients developing recurrent disease did so within the first 2 years after primary treatment. Patients presenting distant disease had a median survival of 12 months, faring worse than those who display local or nodal disease. For patients with nodal or local recurrence, the mean survival after combination therapy (chemotherapy, radiation +/- surgery) was 36.5 months as compared with 17.5 months for those treated with a single modality (surgery or radiation or chemotherapy). The overall survival rate for the 46 patients with recurrence was 37%. Multimodality therapy has shown the best results for recurrent Merkel cell carcinoma thus far, and should be used if tolerated by the patient. Aggressive salvage surgery for local or nodal recurrence is encouraged, because this disease has a tendency to become more destructive upon recurrence. Adjuvant radiation therapy should also be used, if the patient has not exceeded their dose limitations. Disseminated disease, whether primary or recurrent, warrants further investigation in terms of optimal treatment.