Merkel cells and Merkel cell tumors. Ultrastructure, immunocytochemistry and review of the literature

An Extremely Rare Case of Metastatic Merkel Carcinoma of the Liver

Merkel cell carcinoma (MCC) is a rare but highly aggressive skin cancer with neuroendocrine features. The important risk factors in the development of MCC include immunocompromised state, advanced age, and White skin complexion. The pathogenesis is associated with either the presence of Merkel cell polyomavirus or chronic exposure to ultraviolet radiation. MCC usually occurs in the sun-exposed areas of the skin and has the potential for regional and distant metastasis. Only 8% of the cases of MCC present with distant metastatic disease with liver, lungs, bone, and brain being commonly involved. Here, we report such an extremely rare case of a 78-year-old gentleman with a history of cutaneous T-cell lymphoma, who presented to the hospital with abnormally elevated liver enzymes, which on further evaluation was detected to have metastatic MCC of the liver.

Merkel cell carcinoma of the lower lip: A case report and literature review

Merkel cell carcinoma (MCC) is an aggressive primary cutaneous neuroendocrine carcinoma that predominantly affects the sun-damaged skin of the head and neck region, extremities, and trunk of white older individuals. Microscopically, small to intermediate round blue cells show granular nuclei with a salt-and-pepper chromatin pattern, and are usually positive for epithelial and neuroendocrine markers, particularly for cytokeratin 20 in a perinuclear dot-like staining. The 5-year overall survival rate for individuals with localized MCC is 51% and the most common treatment choice is surgery with adjuvant radiotherapy. As far as we know, 23 cases of MCC of the lips have been reported to date in the English-language literature. We herein contribute by reporting a case of MCC affecting the lower lip of an 81-year-old male patient from Rio de Janeiro, Brazil, which likely represents the first reported case from Latin America. A review of the current literature is also included in an effort to familiarize providers with this rare, but potentially lethal neuroendocrine tumor.

Spinal Metastasis from Merkel Cell Carcinoma in an Elderly Male

Merkel cell carcinoma is a cutaneous neuroendocrine malignancy that has an aggressive nature. Classically, it affects the elderly Caucasian population with a predilection for the sun-exposed areas of the body. Pathogenesis has been linked to ultraviolet radiation, immunosuppression, and the Merkel cell polyomavirus. Definitive diagnosis entails histologic evaluation and immunohistochemical staining. With its generalized appearance and tendency for metastasis, a high index of suspicion must be utilized. In this case, we present the unique presentation of Merkel cell carcinoma as a rapidly enlarging lymph node with metastatic disease to the spinal column presenting as new-onset low back and radicular pain.

Heart Block Caused by Cardiac Metastasis From Merkel Cell Carcinoma: A Case Report

Merkel cell carcinoma (MCC) is a rare, rapidly proliferating skin cancer that commonly metastasizes to regional lymph nodes. We present the case of a 73-year-old woman with a history of MCC and non-Hodgkin B-cell lymphoma who presented with second-degree heart block (Mobitz type II) caused by an interatrial mass. Temporary pacing was required before biopsy, which revealed metastatic MCC. Treatment included permanent pacing, anti–programmed cell death ligand 1 immunotherapy, and radiation to the heart resulting in notable decrease in tumor size and normalized cardiac rhythm.

Neuroendocrine Carcinoma of the Skin (Merkel Cell Carcinoma): Immunocytochemical Study of a Case

The immunocytochemical phenotype was evaluated in a case of Merkel cell carcinoma of the skin. Intermediate filaments, i.e. neurofilament, glial fibrillary acid protein, cytokeratins, keratin and panfilament as well as S-100 protein, calcitonin and epithelial membrane antigen were detected by immunoperoxidase methods. Nodular positivity for neurofilament was observed. The remaining intermediate filaments and other markers were negative. Thus the origin of Merkel cell carcinoma appears uncertain and this tumor probably has neuroendocrine activity.

Histologic Mimics of Basal Cell Carcinoma

CONTEXT

- Basal cell carcinoma (BCC) is the most common human malignant neoplasm and is a frequently encountered diagnosis in dermatopathology. Although BCC may be locally destructive, it rarely metastasizes. Many diagnostic entities display morphologic and immunophenotypic overlap with BCC, including nonneoplastic processes, such as follicular induction over dermatofibroma; benign follicular tumors, such as trichoblastoma, trichoepithelioma, or basaloid follicular hamartoma; and malignant tumors, such as sebaceous carcinoma or Merkel cell carcinoma. Thus, misdiagnosis has significant potential to result in overtreatment or undertreatment.

OBJECTIVE

- To review key features distinguishing BCC from histologic mimics, including current evidence regarding immunohistochemical markers useful for that distinction.

DATA SOURCES

- Review of pertinent literature on BCC immunohistochemistry and differential diagnosis.

CONCLUSIONS

- In most cases, BCC can be reliably diagnosed by histopathologic features. Immunohistochemistry may provide useful ancillary data in certain cases. Awareness of potential mimics is critical to avoid misdiagnosis and resulting inappropriate management.

Merkel Cell Carcinoma of the Buccal Mucosa and Lower Lip

Merkel cell carcinoma (MCC) is an uncommon relatively aggressive neuroendocrine dermal neoplasm first described in 1972 as a tumor of the sun exposed skin. Although most MCC affect the skin of the head and neck, rare primarily oral mucosal cases have been documented. Merkel cells are nondendritic neuroendocrine cells that are found not only in the skin but also the oral mucosa and give rise to MCC. Neuroendocrine cells may be found as aggregates in organs or as diffuse or isolated cells within organs and their epithelial lining. They contain peptide hormones and biogenic amines and occur in two forms: dendritic, which are not associated with nerve fibers and non-dendritic, which are associated with nerve fibers. Merkel cells as well as MCC express simple epithelium-type Cytokeratins (8, 18, 19, 20), neurosecretory substances; chromogranin A, synaptophysin, neuron-specific enolase (NSE), adhesion molecules, and villin (intermediate filament). Though weakly, they also express neural markers such as S-100 protein. Cytokeratin 20, and Cluster of differentiation 56, are the two key diagnostic markers for Merkel cells and MCC. Etiology includes UV radiation, the recently described Merkel cell polyomavirus, and long term systemic immunosuppression. The cutaneous and mucosal variants of MCC are considered aggressive tumors with a high risk for local recurrence and metastasis and should be considered in the differential diagnosis of head and neck mucosal lesions. We present two cases of primary Merkel cell carcinoma, one on the buccal mucosa and the other on the lower lip, and discuss the salient histologic, immunohistochemical and clinical features.

Update on Merkel Cell Carcinoma: Epidemiology, Etiopathogenesis, Clinical Features, Diagnosis, and Staging

Merkel cell carcinoma (MCC) is a rare, highly aggressive tumor, and local or regional disease recurrence is common, as is metastasis. MCC usually develops in sun-exposed skin in patients of advanced age. Its incidence has risen 4-fold in recent decades as the population has aged and immunohistochemical techniques have led to more diagnoses. The pathogenesis of MCC remains unclear but UV radiation, immunosuppression, and the presence of Merkel cell polyomavirus in the tumor genome seem to play key roles. This review seeks to update our understanding of the epidemiology, etiology, pathogenesis, and clinical features of MCC. We also review histologic and immunohistochemical features required for diagnosis. MCC staging is discussed, given its great importance in establishing a prognosis for these patients.

Merkel cell carcinoma of unknown primary with lymph node and mesenteric metastasis involving the pancreas and duodenum

Merkel cell carcinoma (MCC) of skin is a rare, aggressive cutaneous malignancy of neuroendocrine origin. MCC predominantly affects elderly Caucasians and has high predilection for sun exposed areas. Histologic exam and immunohistochemical profile is required to establish the diagnosis. It has high propensity for local recurrence and metastasis, and carries poor prognosis. However, metastasis to mesentery involving the duodenum is very uncommon and rarely reported in literature. We hereby describe a patient with lymph node and mesenteric metastasis invading duodenum and pancreas with unknown primary origin of MCC.

A better prognosis for Merkel cell carcinoma of unknown primary origin

BACKGROUND

There is limited evidence that Merkel cell carcinoma (MCC) arising from a nodal basin without evidence of a primary cutaneous (PC) site has better prognosis. We present our experience at 2 tertiary care referral centers with stage III MCC with and without a PC site.

METHODS

Fifty stage III MCC patients were identified between 1996 and 2011. Clinical data were analyzed, with primary endpoints being disease-free survival and overall survival.

RESULTS

Of stage III patients, 34 patients presented with a PC site and 16 patients with an unknown primary (UP) site. Treatment strategies varied; of patients with UP vs. PC sites, 25% vs. 44% underwent combined regional lymphadenectomy and radiation, with an additional 25% vs. 15% receiving chemotherapy. The median disease-free survival for a UP site was not reached vs. 15 months for a PC site (hazards ratio = .48, P = .18). The median overall survival for a UP site was not reached vs 21 months for a PC site (hazards ratio = .34, P = .03). Multivariate analysis showed that UP status was a significant factor in overall survival (P = .002).

CONCLUSIONS

Stage III MCC with a UP site portends a better prognosis than MCC with a PC site.

Early B-cell differentiation in Merkel cell carcinomas: clues to cellular ancestry

Merkel cell carcinoma (MCC) is a highly malignant neuroendocrine nonmelanoma skin cancer, which is associated with the Merkel cell polyoma virus (MCPyV). Recently, expression of the terminal deoxynucleotidyl transferase (TdT) and the paired box gene 5 (PAX 5) has been consistently reported in the majority of MCCs. We tested 21 MCCs for the expression of MCPyV, TdT, PAX5, IgG, IgM, IgA, kappa, and lambda by immunohistochemistry and assessed IgH and Igk rearrangement in all 21 MCCs. All of the MCCs revealed specific expression of PAX5 and 72.8% of the MCCs expressed TdT. In addition, most of the MCCs revealed specific expression of one or more Ig subclasses and kappa or lambda. One MCC did reveal monoclonal IgH and Igk rearrangement next to two other MCCs showing Igk rearrangement. As coexpression of TdT and PAX5 under physiologic circumstances is restricted to pro/pre- and pre-B cells we propose, on the basis of our results, that the cell of origin of MCCs is a pro/pre- or pre-B cell rather than the postmitotic Merkel cells. MCPyV infection and transformation of pro-/pre-B cells are likely to induce the expression of simple cytokeratins as has been shown for SV40 in other nonepithelial cells. This model of cellular ancestry of MCCs might impact therapy and possibly helps to understand why approximately 20% of MCCs are MCPyV-negative.

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.

Primary neuroendocrine (merkel cell) carcinoma of the anterior skull base

A case of a primary neuroendocrine (Merkel cell) carcinoma arising in the anterior skull base involving the dura, both frontal lobes, and the paranasal sinuses is presented. The tumor was completely removed by an enlarged bifrontal transbasal approach. The neuropathological, immunohistological, and electron microscopical investigation revealed all characteristics of a Merkel cell carcinoma, normally presenting as a skin carcinoma of the head and neck. The history, treatment, neuropathology, and possible explanation for this rare manifestation are discussed.

Homo- and heterotypic cell-cell contacts in Merkel cells and Merkel cell carcinomas: heterogeneity and indications for cadherin switching

AIMS

Merkel cell carcinomas (MCCs) are rare but aggressive tumours associated recently with Merkel cell polyomavirus (MCV). As development and progression of several types of carcinomas can be promoted by changes in cell adhesion proteins, the aim of this study was to examine homo- and heterotypic cell contacts of Merkel cells and MCCs.

METHODS AND RESULTS

Merkel cells of healthy glabrous epidermis and 52 MCCs were analysed by double-label immunostaining, immunofluorescence and confocal microscopy. Merkel cells were connected to keratinocytes by E- and P-cadherin, desmoglein 2 and desmocollin 2. In contrast, the vast majority of MCCs (90%) contained N-cadherin, but only 67% and 65% contained E- and P-cadherin, respectively. Interestingly, P-cadherin was absent significantly more frequently in lymph node metastases than in primary tumours and by trend in more advanced clinical stages. Moreover, major subsets of MCCs synthesized desmoglein 2 and, surprisingly, tight junction proteins. No significant differences were observed upon stratification for MCV DNA, detected in 84% of tumours by real-time polymerase chain reaction.

CONCLUSIONS

Assuming that MCCs originate from Merkel cells, our data indicate a switch from E- and P-cadherin to N-cadherin during tumorigenesis. Whether the unexpected heterogeneity of junctional proteins can be exploited for prognostic and therapeutic purposes will need to be examined.

Merkel Cells, Normal and Neoplastic: An Update

Merkel cells (MC) occur in the basal epidermal layer, hair follicles, and oral mucosa, as complexes with sensory axons. The axons transduce slowly adapting type I mechanoreception, and MC modulate their sensitivity. MC also determine and maintain the 3-dimensional epidermal structure. They have neuroendocrine granules, rigid spinous processes, and desmosomal junctions with each other and with keratinocytes. Rare MC are dermaWl. Current evidence supports a basal cell origin. Merkel cell carcinomas (MCC) occur mostly in sun-exposed skin in old age. Trabecular, intermediate, or small cell in pattern, MCC have neuroendocrine granules, intercellular junctions, rigid spinous processes, and a paranuclear collection of intermediate filaments staining for cytokeratin 20. Most MCC behave indolently, but those with the small cell pattern, and some with the intermediate pattern, are aggressive and rapidly fatal.

A unique case of merkel cell carcinoma and chronic lymphocytic leukaemia presenting in a single cutaneous lesion (collision tumour)

A 58-year-old man with 10 year history of chronic lymphocytic leukaemia (CLL) presented with a bulging mass (3.2×1.6×1.5 cm) in the right anterior abdominal wall. On microscopic examination the mass was found to be an epithelial neoplasm in the background of lymphoid proliferation. The epithelial cells were of moderate size, with scant cytoplasm and round nuclei, forming glandular, alveolar or sheet-like structures. These cells were immunoreactive for cytokeratin 20, chromogranin and synaptophysin. The above findings supported a diagnosis of Merkel cell carcinoma (MCC). The background small lymphocytes expressed phenotypic markers of B cells (CD20) and CD5, consistent with his known diagnosis of CLL. The incidence of a patient with a known history of CLL who develops a secondary MCC is rare. This is believed to be the second case report of a single lesion containing CLL and MCC.

Spinal extra-dural metastasis from Merkel cell carcinoma: a rare cause of paraplegia

We report a rare case of Merkel cell carcinoma with extra-dural spinal metastasis causing paraplegia. There are only four reported cases in literature. A 57-year-old lady presented with a breast lump, multiple truncal skin swellings, low back pain and rapidly progressive paraplegia. MRI showed multiple epidural soft tissue masses causing neural compression. A biopsy from the truncal skin lesion was diagnosed as Merkel cell carcinoma (MCC). Posterior decompression and tumor debulking at all three sites of neural compression was performed. Histopathology of the epidural tumor was consistent with MCC and the diagnosis was confirmed by immuno-histochemistry staining for cytokeratin-20. She was started on chemotherapy and radiotherapy. One month after diagnosis she died due to extensive metastasis. The short term palliative response seen in our patient demonstrates the poor prognosis for patients with spinal metastasis.

Neuroendocrine carcinoma arising in soft tissue: three case reports and literature review

Background

Neuroendocrine tumours (NET) are tumours arising from neuroendocrine cells of neural crest origin. They are characterised by the presence of neurosecretory granules which react positively to silver stains and to specific markers including neuron specific enolase, synaptophysin and chromogranin. Metastasis to the skin occurs infrequently but primary soft tissue NET is excessively rare.

Case presentation

We report our experience with 3 such cases. In the first case, the NET originated in muscle and was treated with wide surgical excision and adjuvant radiotherapy. The second case presented as a subcutaneous mass in the foot and the tumour was positive on ¹²³I mIBG scan. She has had prolonged recurrence-free survival following primary hypo-fractionated radiotherapy. In the third case, a cutaneous nodule proved to be a NET and at surgery, lymph node disease was present. He has remained disease-free after surgical excision without the need for external beam radiotherapy.

Conclusion

These tumours appear to have a good prognosis. Complete excision offers potentially curative treatment. Adjuvant radiotherapy may be helpful when the tumour margin is narrow. For patients with unresectable disease or where surgery would not be appropriate, radiotherapy appears to be an effective therapeutic option.

Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous cancer that predominately affects elderly Caucasians with fair skin and has a propensity for local recurrence and regional lymph node metastases. A variety of terms have been used to describe this tumor, including trabecular cell carcinoma, neuroendocrine or primary small cell carcinoma of the skin, and anaplastic cancer of the skin. Although the skin lesion is most commonly found on sun-exposed areas of the head and neck or extremities, it can occur on the trunk, genitalia, and perianal region. The median age is 69 years, but it may occur earlier and more frequently in immunosuppressed patients. Patients with MCC frequently present with a nonspecific erythematous or violaceous firm nodule or small plaque that may be surrounded by small satellite tumors. MCC usually arises in the dermis and extends into the subcutis. It may be difficult to accurately diagnose MCC by light microscopy alone and ancillary techniques, including electron microscopy and immunohistochemistry, may be necessary to make a definitive diagnosis. Management of MCC is dependent on stage of the disease and is hampered by its rarity and lack of randomized trials. Nonetheless, for localized disease most guidelines include wide local excision of the primary tumor either alone or with radiation therapy. Sentinel lymph node biopsy can be helpful in staging and prognosis, but its benefit in survival remains to be seen. Systemic chemotherapy, akin to regimens for small cell carcinoma of the lung, may be considered as an adjuvant following surgery or to treat locoregional or distant disease. The prognosis of MCC is variable. Some patients with localized disease have an indolent course and are well controlled with local excision alone. On the other hand, many tumors are aggressive and have a tendency for locoregional recurrence and distant metastases. Such patients have a grim prognosis with a median survival of 9 months. Successful outcomes are most often seen in patients with early diagnosis and complete excision.

Merkel cell carcinoma of the tongue and head and neck oral mucosal sites

Merkel cell carcinoma (MCC) is an uncommon primarily dermal malignancy of relatively aggressive biologic course. Several presentations in the mucosa of the head and neck region have been reported in the literature, and 3 such patients have recently been seen at our institution. We review this recent experience and present the first reported primary lingual MCC in a 57-year-old caucasian man. We provide a review of oral mucosal MCC and guidelines for histopathologic and immunohistochemical diagnosis. Merkel cell carcinoma should be included in the differential diagnosis of head and neck mucosal lesions, especially if the tumor is submucosal, and MCC may involve the tongue. Mucosal MCC is aggressive, and there is a high risk for local recurrence and regional and distant metastasis. Fulminating courses are often seen. We discuss our treatment policies based on the current 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.

Treatment of Merkel Cell Carcinoma

PURPOSE

The purpose of this study was to evaluate the treatment of Merkel cell carcinoma.

MATERIALS AND METHODS

We reviewed 85 cases of Merkel cell carcinoma. There were 68 males and 17 females. The majority of cases involved head and neck sites (48%), followed by the extremities (38%) and trunk (14%). Sixty-seven percent of the patients had stage I disease that was localized to the skin of origin at presentation. Twenty-five percent and 8% were stage II (nodal metastasis) and stage III (distant metastasis), respectively. Surgical intervention included local or wide local excision +/- nodal dissection (68%), radical resection +/- nodal dissection (22%), and amputation (4%). Five patients (6%) underwent biopsy only because of metastatic disease or unresectability at presentation. Fifty-one percent received adjuvant therapy consisting of external beam radiation therapy and/or combination chemotherapy.

RESULTS

With an average follow-up time of 39.5 months, 12% had persistent disease and 40% had recurrent disease. The median time to recurrence was 8 months with a mean of 10.6 months. Although the addition of adjuvant therapy did not affect survival, the recurrence rate was 32.5% for surgery +/- adjuvant radiation therapy +/- chemotherapy as compared with 52.7% for surgery-only patients. Although the 40.7% recurrence rate for patients receiving surgery and adjuvant radiation therapy was approximately the same as for patients receiving surgery and adjuvant chemotherapy (40%), the effect of systemic chemotherapy on recurrence is less clear as a result of the small number of patients who received such therapy. Although tumor size and site of presentation were not observed to be statistically significant in overall survival, significant differences were observed based on sex and tumor stage. For females, the median survival time was 96 months (mean, 94.5 months) compared with 63 months (mean, 76.8 months) for males. This difference was significant (P < 0.01). Patients presenting with low-stage (stage I) disease had a significant (P < 0.01) survival benefit when compared with high-stage individuals (stages II and III). The 5-year actuarial survival rates were 68% and 42%, respectively.

CONCLUSION

In this retrospective study, surgery remains the primary modality for Merkel cell carcinoma, and adjuvant radiation therapy +/- systemic chemotherapy reduces local recurrence. Female patients and those who present with early-stage disease appear to have a better prognosis.

Merkel cell carcinoma: a clinicopathologic study with prognostic implications

BACKGROUND

Merkel cell carcinoma (MCC) is a frequently aggressive neuroendocrine malignancy of the skin that presents in sun-exposed areas on elderly patients. Although originally described over 30 years ago, many aspects of MCC remain to be defined. Of particular importance is the need to identify prognostic factors capable of predicting the biological behavior of these tumors. Knowledge of these factors may help in determining which patients require more aggressive treatment regimens. In this study, we examined 25 cases of MCC with an attempt to identify clinical, histopathological, or immunohistochemical features capable of predicting disease outcome.

METHODS

Features that we evaluated in each case included age, gender, race, tumor location, tumor size, depth of invasion, growth pattern, lymphocytic infiltration, mitotic activity, ulceration, necrosis, vascular invasion, and perineural invasion. In addition, we examined neural cell adhesion molecule and cytokeratin-20 expression using immunohistochemical methods.

RESULTS

We found that most patients were males (84%) with an average age of 74 years. The tumors were located on the head and neck (68%) and upper extremities (32%). Overall, 64% of the patients developed metastatic disease to regional lymph nodes or distant sites (average follow-up time of 21 months). Local recurrence was also common, occurring in 29% of the patients. The overall 1- and 2-year survival rates were 80 and 53%, respectively. Histopathological examination revealed tumors with an average size of 7.2 mm. Common features included invasion into the subcutaneous adipose tissue, solid growth pattern, tumor necrosis, and vascular and perineural invasion. Findings that had a statistically significant correlation with poor outcome included tumor size > or =5 mm (p = 0.047), invasion into the subcutaneous adipose tissue (p = 0.005), diffuse growth pattern (p = 0.040), and heavy lymphocytic infiltration (p = 0.017). The remaining findings, including the immunohistochemical results, did not correlate with disease outcome. Using logistic regression models, we show that depth of invasion and degree of lymphocytic infiltration are strong predictors of disease outcome.

CONCLUSIONS

The current controversies regarding the treatment of early-stage MCC (i.e., localized disease) underscore the importance of identifying clinicopathological features capable of predicting tumor behavior. In this study, we have identified several prognostic features in MCC. Perhaps, these features may prove useful in identifying patients who require more aggressive treatment regimens.

Epidemiology of primary Merkel cell carcinoma in the United States

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer.

OBJECTIVE

We sought to describe primary MCC incidence trends, epidemiology, and predictors of survival.

METHODS

The population covered by the Surveillance, Epidemiology, and End Results Program was analyzed as a prospective cohort. We measured age-adjusted incidence rates (per 100,000 person-years) and effect of age, anatomic site, and stage on survival.

RESULTS

Incidence was higher in males (0.34) than in females (0.17). Cases (n = 1034) occurred mostly in whites (94%), in people older than 65 years (76%), and at the head (48%). The 5-year relative survival was 75%, 59%, and 25% for localized, regional, and distant MCC, respectively. Female sex, limb presentation, localized disease, and younger age were positive predictors of survival.

CONCLUSION

The highest incidence of MCC was observed in whites, males, and in people older than 65 years. Only 49% of cases were reported as localized. Better survival was associated with limb localization, early-stage disease, younger age, and female sex.

A Case of Intraepidermal Merkel Cell Carcinoma within Squamous Cell Carcinoma In-Situ: Merkel Cell Carcinoma In-Situ?

We report a case of a 79-year-old Caucasian male who presented with a wrist lesion of combined intraepidermal Merkel cell carcinoma and squamous cell carcinoma in-situ. The two tumors were tightly admixed and distinct, and both were without any dermal or invasive components. No features of transition between the two tumors were seen. We suggest the term Merkel cell carcinoma in situ for tumors that demonstrate exclusive intraepidermal proliferation of neuroendocrine cells.

CD56: a useful marker for diagnosing Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) of the skin is an aggressive but rare malignant neuroendocrine tumor. For its pathological diagnosis, we use a panel of immunohistochemical markers, such as cytokeratin 20 (CK 20), epithelial membrane antigen (EMA), chromogranin A, neuron specific enolase (NSE), synaptophysin, and Leu7 (CD57) to demonstrate its epithelial and neuroendocrine features. CD56, or neural cell adhesion molecule (NCAM), has been demonstrated recently as the tumor marker of the pulmonary neuroendocrine cell system. Its expression in MCC, however, has still rarely been investigated. Furthermore, in such very few previous studies on NCAM expression in MCC, all the tumor cells were not necessarily demonstrated to express NCAM.

OBJECTIVES

To study the immunoreactivity of CD56 in MCC, especially using a monoclonal antibody of a clone 1B6, different from those adopted in the previous reports.

METHODS

We reexamined CD56 expression immunohistochemically in five MCC cases, along with the conventional panel of markers described above, using paraffin-embedded tissue sections.

RESULTS

CD56 revealed the most diffuse and intense positive staining, which was noted along the cell borders, in all specimens compared with other neuroendocrine tumor markers.

CONCLUSIONS

The results of our study indicate that CD56, especially a new monoclonal antibody (clone 1B6), is a useful immunohistochemical marker for MCC.

Imaging of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, highly malignant cutaneous tumor, primarily of the head and neck, that requires timely diagnosis, adequate staging, and aggressive therapy. MCC tends to be overlooked in the early stage, has a high propensity for invading local and regional nodal basins, and exhibits a high postoperative recurrence rate, with distant thoracic, abdominal, and central nervous system metastases. Conventional radiography and cross-sectional imaging show lesions similar to those originating from other small cell carcinomas. Nuclear medicine procedures such as sentinel node scintigraphy, somatostatin receptor scintigraphy, and positron emission tomography may be used to supplement judicious cross-sectional imaging evaluation, thereby adding diagnostic value in staging and providing therapeutic guidance. Ultimately, however, the diagnosis relies exclusively on pathologic findings at immunohistochemical staining and electron microscopy. The rarity of MCC and the resulting insufficient awareness of this neoplasm often delay correct identification and treatment, which essentially consists of wide-margin surgical excision of the primary tumor and local and regional radiation therapy. To date, clinical information is still insufficient to fully appreciate the role of imaging in MCC management. A better imaging algorithm is expected with increased awareness and improved clinical understanding of this uncommon skin neoplasm.

The effect of aloe emodin on the proliferation of a new merkel carcinoma cell line

A free-floating cell line has been established from a metastatic lesion of a Merkel cell carcinoma (MCC) patient. The cell line was characterized by immunocytochemical reactions with antibodies against the epithelial and neuroendocrine antigens: cytokeratin 20, neuron-specific enolase, chromogranin A, neurofilament protein, synaptophysin, and calcitonin. Karyotype analysis of the MCC cells showed deletion in chromosomes 3 and 7, loss of chromosome 10, and several translocations in other chromosomes. No mutation was detected in the TP53 gene, after analyzing the complete coding region. Growth factors such as basic fibroblast growth factor, transforming growth factor-beta, and nerve and epidermal growth factors had no effect on the proliferation of the cells. The differentiation-inducing agents sodium butyrate and dimethyl sulfoxide, especially the former, markedly inhibited the proliferation of the MCC cells. Aloe emodin, a natural constituent of aloe vera leaves, significantly inhibited the growth of MCC cells. Aloe emodin has been reported to be nontoxic for normal cells but to possess specific toxicity for neuroectodermal tumor cells. Differentiation-inducing agents, and aloe emodin, merit further investigation as potential agents for treating MCC.

[Parotid metastases of a neuroendocrine cutaneous carcinoma]

A case of metastatic Merkel-cell carcinoma to lymph nodes on the left side of the neck nad left parotid is described. Neuroendocrine cutaneous carcinoma, also called Merkel cell carcinoma (MCC), is an uncommon primary skin tumor most often seen in elderly. Literature is reviewed and comment about more important features of these lesions, like differential diagnosis, prognosis and treatment.

Merkel cell (neuroendocrine) carcinoma of the vulva. A case report with immunohistochemical and ultrastructural findings and review of the literature

A new case of primary Merkel cell carcinoma (MCC) of the vulva is reported and the literature reviewed for noting its clinical presentation, microscopic, immunohistochemical and ultrastructural features, as well as for establishing the role of immunohistochemistry in the ultimate diagnosis of this uncommon and aggressive tumor. The lesion occurred in a 79 year old patient. Histologically, the tumor was composed of intradermal small cells with high mitotic index and frequent apoptosis. The immunohistochemical study showed positivity for wide spectrum and low molecular weight cytokeratins, epithelial membrane antigen, neurofilaments, neuron specific enolase and chromogranin A. Electron microscopy revealed intermediate filaments in a typical globular paranuclear arrangement. The coexpression of cytokeratins (including cytokeratin 20) and neurofilaments, both in typical globular paranuclear arrangement, made possible the diagnosis of MCC, differentiating it from other malignant small cell tumors such as neuroendocrine metastatic carcinoma.

Two cases of merkel cell tumour arising in patients with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) has been associated with an increased incidence of second neoplasms, especially skin cancers such as basal and squamous cell carcinomas. No association with the rarer skin cancer, the Merkel cell tumour (MCT), has previously been reported. Two patients with MCT had a previous diagnosis of CLL. MCT is an aggressive skin cancer, as up to 45% of patients have lymph node involvement at presentation and 5-year disease-free survival is as low as 30%. It is most commonly found on sun-exposed areas of the body, and ultraviolet radiation together with drug-induced or CLL-induced immunosuppression may be the underlying mechanism in the observed relationship between CLL and other skin cancers.

Neuroendocrine (Merkel cell) carcinoma of the oral mucosa: report of a case with immunohistochemical study and review of the literature

Merkel cell carcinoma (Mcc) is an uncommon and aggressive tumour with neuroendocrine features that occur predominantly in the head and neck region. The rarity of this tumour, especially when it arises in the oral mucosa, makes both early identification and standardisation of treatment difficult, particularly as regards complementary treatment. The availability of monoclonal antibodies with restricted specificity for some antigens thought to be related to neuroendocrine carcinomas, such as Merkel cell carcinoma, and ultrastructural studies offer some new leads to investigation. This has allowed, a greater number of these tumours to be discovered, thereby increasing the chances of effective management. A case of Mcc of the floor of the mouth is reported, together with the results of cytokeratin, neuron specific enolase and chromogranin immunohistochemistry.

Diagnostic relevance of chromosomal in-situ hybridization in Merkel cell carcinoma: targeted interphase cytogenetic tumour analyses

AIMS

To resolve the conflicting diagnoses of five pathologists (which included well-differentiated neuroendocrine carcinoma, malignant carcinoid, undifferentiated small-cell carcinoma, primitive neuroectodermal tumour, metastases of small-cell lung carcinoma (SCLC) and Merkel cell carcinoma (MCC)), and tumour-free lungs after necropsy, we investigated an alarmingly metastasizing MCC in a 32-year-old Caucasian man using chromosomal in-situ hybridization (CISH). Differences in incidence and course in males and females also prompted targeted analyses for chromosomes X and Y. The lesion was also analysed for p53 gene mutations.

METHODS AND RESULTS

Paraffin sections of the thorax, buccal lymph nodes and scalp tumours were stained with haematoxylin and eosin. Immunohistochemistry was performed with antibodies against pancytokeratin, keratin 20, neuron-specific enolase (NSE), chromogranin, neurofilaments and vimentin, among others. Sections (5-6 microm) of the tumours were analysed with alpha-satellite probes for chromosomes 1, 6, 7, 11, 12, 17, 18, X and Y using CrSH; and exons 5-9 of the p53 gene were examined by polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP) methods. Although positive for pancytokeratin, keratin 20, chromogranin, NSE, synaptophysin and vimentin, the similarity in antigen profiles expressed by SCLC and MCC prevented a definitive tumour diagnosis. Chromosomal in-situ hybridization, however, revealed trisomies 1 and 11, two frequent aberrations in MCC, and trisomy 18. Moreover, 71% of the tumour cells had two to three copies of X, whereas 98% of the cell nuclei in the hair follicles and normal epidermis (purported Merkel cell origins) displayed one X chromosome. No mutations were detected in the five exons of the p53 gene examined.

CONCLUSIONS

Had CISH been performed earlier, treatment may have been tailored specifically to suit MCC, since MCC and SCLC have different therapeutic strategies. Finally, chromosome X may be of prognostic relevance in MCC, which apparently predominates in females and yet shows poorer prognosis in males, and hence be worthy of further investigation.

Cytokeratin 20: a marker for diagnosing Merkel cell carcinoma

Merkel cell carcinoma is an aggressive cutaneous neoplasm that is often difficult to diagnose because of its histologic and immunohistochemical similarity to metastatic oat cell carcinomas and other cutaneous neoplasms. Our purpose was to determine the utility of immunoperoxidase staining of cytokeratin 20 (CK 20), a newly discovered intermediate filament protein, in Merkel cell carcinomas and other cutaneous tumors. Sixty-one tumors were sectioned and stained with antibodies directed at CK 20. The staining of Merkel cell carcinomas was compared with metastatic oat cell carcinomas, lymphomas, squamous cell carcinomas, basal cell carcinomas, melanomas, metastatic carcinoids, spiradenomas, eccrine carcinomas, adenoidcystic carcinoma, sebaceous carcinomas, hidradenomas, sebaceous epitheliomas, trichoblastomas, mixed tumors, and metastatic adenocarcinomas. Nine of 10 Merkel cell carcinomas stained with antibody to CK 20. Two metastatic carcinomas to the skin were also positive. One hidradenoma and one squamous carcinoma exhibited focal staining, but were otherwise negative. All other tumors were nonstaining. Cytokeratin 20 is a sensitive and specific marker for Merkel cell carcinoma and is helpful in distinguishing between Merkel cell carcinoma and other malignant and benign neoplasms.

Nonmelanoma skin cancer

Nonmelanoma skin cancers encompass a vast array of malignancies: adventitial, vascular, neuroendocrine, hematologic, adnexal, and epithelial. The skin is also a major site for metastasis of internal disease. With an understanding of the frequency of presentation, clinical distribution, and appearance, the clinician is able to provide an accurate diagnosis for most lesions. Because there are so many nonmelanoma skin cancers, the focus here is on those with a high frequency or significant morbidity. The treatment of nonmelanoma skin cancer is constantly evolving; therefore, emphasis is on diagnosis.