Expression of bcl-2 and p53 in Merkel cell carcinoma. An immunohistochemical study

Navitoclax combined with Alpelisib effectively inhibits Merkel cell carcinoma cell growth in vitro

Background:

Merkel cell carcinoma (MCC) is a highly malignant skin cancer. Despite major treatment improvements during the last decade, up to 50% of patients do not respond to therapy or develop recurrent disease. For these patients, alternative treatment options are urgently needed. Here, we assessed the efficacy of the combination of the BCL-2 inhibitor Navitoclax and the PI3K p110α inhibitor Alpelisib in MCC cell lines.

Methods:

The expression of BCL-2 was assessed by immunohistochemistry in MCC and MCC cell lines. Treatment with Navitoclax and Alpelisib alone and in combination was performed on four MCC cell lines. The decrease of cell viability during treatment was assessed by XTT assay and visualized for the combinations by 3D combinatorial index plotting. The increase of apoptotic cells was determined by cleaved PARP Western blotting and Annexin V staining.

Results:

Some 94% of MCCs and all three MCPyV-positive cell lines showed BCL-2 expression. Navitoclax monotreatment was shown to be highly effective when treating BCL-2-positive cell lines (IC₅₀-values ranging from 96.0 to 323.0 nM). The combination of Alpelisib and Navitoclax resulted in even stronger synergistic and prolonged inhibitions of MCC cell viability through apoptosis up to 4 days.

Discussion:

Our results show that the anti-apoptotic BCL-2 is frequently expressed in MCC and MCC cell lines. Inhibition of BCL-2 by Navitoclax in combination with Alpelisib revealed a strong synergy and prolonged inhibition of MCC cell viability and induction of apoptosis. The combination of Navitoclax and Alpelisib is a novel potential treatment option for MCC patients.

Merkel Cell Polyomavirus and Merkel Cell Carcinoma

Viruses are the cause of approximately 15% of all human cancers. Both RNA and DNA human tumor viruses have been identified, with Merkel cell polyomavirus being the most recent one to be linked to cancer. This virus is associated with about 80% of Merkel cell carcinomas, a rare, but aggressive cutaneous malignancy. Despite its name, the cells of origin of this tumor may not be Merkel cells. This review provides an update on the structure and life cycle, cell tropism and epidemiology of the virus and its oncogenic properties. Putative strategies to prevent viral infection or treat virus-positive Merkel cell carcinoma patients are discussed.

Combining DNA Damage Induction with BCL-2 Inhibition to Enhance Merkel Cell Carcinoma Cytotoxicity

Merkel cell carcinoma (MCC) is a highly lethal skin cancer. MCC tumors rapidly develop resistance to the chemotherapies tested to date. While PD-1/PD-L1 immune checkpoint blockade has demonstrated success in MCC treatment, a significant portion of MCC patients are nonresponsive. Therefore, the pressing need for effective MCC chemotherapies remains. We screened a library of natural products and discovered that one compound, glaucarubin, potently reduced the viability of Merkel cell polyomavirus (MCPyV)-positive MCCs, while remaining nontoxic to primary human fibroblasts and MCPyV-negative MCC cell lines tested. Protein array and Western blot analyses revealed that glaucarubin induces DNA damage and PARP-1 cleavage that correlates with the loss of viability in MCC cells. However, high basal expression of the antiapoptotic factor BCL-2 allowed a subpopulation of cells to survive glaucarubin treatment. Previous studies have shown that, while targeting BCL-2 family proteins significantly decreases MCC cell viability, BCL-2 antisense therapy alone was insufficient to inhibit tumor growth in patients with advanced MCC. We discovered that treatment with an FDA-approved BCL-2 inhibitor in the context of glaucarubin-induced DNA damage led to near complete killing in multiple MCPyV-positive MCC cell lines that express high levels of BCL-2. The combination of DNA damage-induced apoptosis and BCL-2 inhibition thus represents a novel therapeutic strategy for MCPyV-positive MCCs.

Advances in the Understanding of Skin Cancer: Ultraviolet Radiation, Mutations, and Antisense Oligonucleotides as Anticancer Drugs

Skin cancer has always been and remains the leader among all tumors in terms of occurrence. One of the main factors responsible for skin cancer, natural and artificial UV radiation, causes the mutations that transform healthy cells into cancer cells. These mutations inactivate apoptosis, an event required to avoid the malignant transformation of healthy cells. Among these deadliest of cancers, melanoma and its 'younger sister', Merkel cell carcinoma, are the most lethal. The heavy toll of skin cancers stems from their rapid progression and the fact that they metastasize easily. Added to this is the difficulty in determining reliable margins when excising tumors and the lack of effective chemotherapy. Possibly the biggest problem posed by skin cancer is reliably detecting the extent to which cancer cells have spread throughout the body. The initial tumor is visible and can be removed, whereas metastases are invisible to the naked eye and much harder to eliminate. In our opinion, antisense oligonucleotides, which can be used in the form of targeted ointments, provide real hope as a treatment that will eliminate cancer cells near the tumor focus both before and after surgery.

Merkel cell carcinoma of the eyelid: A review

Merkel cell carcinoma (MCC) is a rare, aggressive tumor of both epithelial and neuroendocrine origin, which carries a mortality rate of up to 40%. MCC tumors typically present as painless, expanding nodules on the sun-exposed skin areas of older, white patients. Eyelid and periocular tumors comprise approximately 2.5% of all cases of MCC and may be mistaken for chalazia or basal cell carcinomas. Immunosuppression is a significant risk factor, particularly in solid-organ-transplant recipients, patients with chronic lymphocytic leukemia, and patients with HIV. Sentinel lymph node biopsy is often used for accurate staging of head and neck MCC. Treatment includes wide local excision, commonly with the addition of radiotherapy for improved locoregional disease control. Historically, adjuvant chemotherapy had been reserved for metastatic disease, but immunotherapy and targeted chemotherapies are currently being investigated for use in primary disease. The clinical characteristics of all available published cases of eyelid MCC are summarized in this article.

Fine-needle aspiration cytology of Merkel cell carcinoma-a review of 69 cases

This study reviewed the clinical presentation, cytologic findings, and the immunophenotype of 69 Merkel cell carcinoma (MCC) cases sampled by fine-needle aspiration (FNA).  Demographic and clinical data, the cytology findings, and results of ancillary testing were reviewed.  Median patient age was 78 years (37-104) with a 1:1.8 female to male ratio. The most common FNA sites sampled included lymph nodes in the neck, the axillary region, the inguinal region and the parotid gland. Most patients had a history of MCC (68%) and/or non-MCC malignancy (70%).  The common cytologic pattern was a cellular smear with malignant cells arranged in a dispersed pattern with variable numbers of disorganized groups of cells. Cytoplasm was scant or absent and nuclei showed mild to moderate anisokaryosis, stippled chromatin, inconspicuous nucleoli, and nuclear molding. Numerous apoptotic bodies were often present.  Cell block samples (28 cases) were usually positive for cytokeratins in a perinuclear dot pattern, including 88% of cases with CK20 positivity. CD56 was the most sensitive (95%) neuroendocrine marker on cell blocks and was also positive with flow cytometry in nine cases tested.  MCC is most commonly seen in FNA specimens from the head and neck of elderly patients, often with a history of previous skin lesions. Occasional cases present in younger patients and some may be mistaken for other round blue cell tumors, such as lymphoma. CD 56 may be a useful marker in cell block preparations and in flow cytometric analysis of MCC.

Merkel cell carcinoma dependence on bcl-2 family members for survival

Merkel cell carcinoma (MCC), a rare but aggressive cutaneous neoplasm with high metastatic potential, has a poor prognosis at late stages of disease with no proven chemotherapeutic regimens. Using an enriched culture medium, we established and characterized 11 MCC cell lines for Bcl-2 family profiling and functional studies. Immunoblot analysis revealed collectively high protein levels of pro-survival Bcl-2 members in cell lines and a panel of MCC tumors. Down-regulation of individual Bcl-2 proteins by RNAi promoted death in a subset of MCC cell lines, whereas simultaneous inhibition of multiple family members using the small molecule antagonist ABT-263 led to dramatic induction of cell death in 10 of 11 lines. ABT-263 induced Bax-dependent apoptosis with rapid cleavage of caspase-3 and PARP, regardless of Bcl-2 family profile or presence of Merkel cell polyomavirus. Furthermore, ABT-263 treatment led to rapid and sustained growth suppression of MCC xenografts from a representative cell line, accompanied by a striking increase in apoptosis. Our results establish that concurrent inhibition of multiple pro-survival Bcl-2 proteins leads to effective induction of apoptosis, and strongly support the concept that targeting MCC addiction to these molecules may be useful therapeutically by reversing an intrinsic resistance to cell death.

Expression of β-catenin and cyclin D1 in Merkel cell carcinomas of the head and neck

BACKGROUND

Merkel cell carcinomas (MCC) are very aggressive tumors of the sun-exposed skin with a high potential to metastasize. Little is known about the genesis of MCC and very few prognostic markers have been detected so far. The Wnt pathway protein β-catenin and the cell cycle protein cyclin D1 are two promotors of tumor growth and are expressed in a variety of malignant neoplasms such as lymphomas, thyroid, breast cancer, and many others.

PATIENTS AND METHODS

Tissue samples of 27 patients with MCC were immunohistochemically stained for β-catenin and cyclin D1 and correlated with overall survival of patients. In addition, western blot analysis was carried out in the two MCC cell lines MCC-13 and MCC-26.

RESULTS

β-catenin showed a cytoplasmatic expression of 10-30 % in 11 samples and an expression lower than 10 % in eight samples. Nuclear staining was visible in two samples. None of the 27 samples expressed cyclin D1.

CONCLUSION

Neither cyclin D1 nor β-catenin was expressed in a statistically significant manner, concluding that the development of MCCs is independent of β-catenin and cyclin D1 expression and these proteins are not suitable as prognostic markers. We could describe the expression pattern of cyclin D1 for the first time.

Expression of CXCR4, E-cadherin, Bcl-2, and survivin in Merkel cell carcinoma: an immunohistochemical study using a tissue microarray

Merkel cell carcinoma (MCC) is a rare but highly aggressive cutaneous malignancy with a mortality rate exceeding that of melanoma. Although smaller studies of markers of progression have been performed, large-scale investigation has been difficult due to the rarity of this tumor. Investigation of 4 potential immunohistochemical progression markers using an MCC tissue microarray was performed. An immunohistochemical analysis of CXCR4, E-cadherin, Bcl-2, and Survivin was performed on a tissue microarray of two hundred twenty-seven 0.6-mm tumor cores-110 primary, 73 local/regional metastatic, and 44 distant metastatic-from 87 patients, 23 of which were sampled 2 or more times. There was a statistically significant increase in immunoreactivity to CXCR4 and Survivin in local/regional nodal MCC metastases compared with primary and distant metastatic lesions. No significant differences by disease location were found for either Bcl-2 or E-cadherin. These results suggest a potential role for CXCR4 and Survivin in MCC tumor progression. However, previous data from other studies suggesting a role for Bcl-2 and E-cadherin in MCC progression are not confirmed in this larger sample. Further discovery of additional markers are needed to better characterize this rare but deadly malignancy.

Distinct gene expression profiles of viral- and nonviral-associated merkel cell carcinoma revealed by transcriptome analysis

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine tumor with high mortality rates. Merkel cell polyomavirus (MCPyV), identified in the majority of MCC, may drive tumorigenesis via viral T antigens. However, mechanisms underlying pathogenesis in MCPyV-negative MCC remain poorly understood. To nominate genes contributing to pathogenesis of MCPyV-negative MCC, we performed DNA microarray analysis on 30 MCCs. MCPyV status of MCCs was determined by PCR for viral DNA and RNA. 1593 probe-sets were differentially expressed between MCPyV-negative and -positive MCC, with significant differential expression defined as at least 2-fold change in either direction and p-value of ≤ 0.05. MCPyV-negative tumors showed decreased RB1 expression, whereas MCPyV-positive tumors were enriched for immune response genes. Validation studies included immunohistochemistry demonstration of decreased RB protein expression in MCPyV-negative tumors and increased peritumoral CD8+ T lymphocytes surrounding MCPyV-positive tumors. In conclusion, our data suggest that loss of RB1 expression may play an important role in tumorigenesis of MCPyV-negative MCC. Functional and clinical validation studies are needed to determine whether this tumor suppressor pathway represents an avenue for targeted therapy.

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.

Bcl-2 expression indicates better prognosis of Merkel cell carcinoma regardless of the presence of Merkel cell polyomavirus

Merkel cell carcinoma (MCC) is an aggressive dermal tumour of neuroendocrine origin. The recently found Merkel cell polyomavirus (MCV) integrates clonally in the tumour genome, which suggests an important role in the pathogenesis of the disease. Previous small-scale studies have detected anti-apoptotic protein bcl-2 in 80 % of MCC tumours, but its correlation to the prognosis of MCC remains controversial. Our aim was to clarify the correlation of immunohistochemical expression of bcl-2 to MCV presence and MCC prognosis. We analyzed 116 primary MCC specimens with corresponding clinical data by immunohistochemistry for bcl-2. The presence of MCV DNA had been analyzed by quantitative PCR for 108 tumours. The correlations were analyzed statistically. Of the primary MCC samples, 85 % were bcl-2 positive. No significant differences in MCV DNA occurred between the bcl-2-positive and bcl-2-negative tumours. Local and systemic metastasis was more common in patients with bcl-2 negative tumours (33 %) than in patients with bcl-2-positive tumours (12 %; p = 0.04) at the time of diagnosis. The mean overall survival was higher in patients with bcl-2-positive tumours than of those with negative tumours (mean survival 1,814 days (5.0 years) vs. 769 days (2.1 years), p = 0.01). Bcl-2 positivity indicates better clinical stage at the time of diagnosis and a longer survival in MCC.

Increasing tumor thickness is associated with recurrence and poorer survival in patients with Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous neuroendocrine tumor usually occurring on sun-exposed skin in elderly patients. Clinical and pathologic factors associated with disease progression and mortality in patients with MCC are poorly defined. Recently, it has been reported that p63 expression in primary MCC is strongly associated with clinical outcome.

METHODS

MCC patients diagnosed between July 1, 1993 and July 31, 2009 were identified from the surgical pathology records of the Sydney South West Area Health Service. Clinical, pathologic, treatment, and survival data were obtained and immunohistochemical analyses for p53, p63, and Ki-67 were performed. The associations of clinical and pathologic features with disease-free and disease-specific survival were analyzed.

RESULTS

Ninety-five patients were identified (67 males, 28 females; median age at diagnosis of primary MCC 76 [range, 42-93] years). Increasing primary tumor thickness was significantly associated with poorer disease-free survival (5-year survival 18 % in tumors >10 mm thick compared with 69 % for patients with tumors ≤10 mm thick, p = 0.002) and disease-specific survival (5-year survival 74 % in tumors >10 mm thick compared with 97 % for patients with tumors ≤10 mm thick, p = 0.006). There was a strong positive correlation between the Ki-67 index (proportion of Ki-67-positive tumor nuclei) and tumor thickness (r = 0.39, n = 45, p = 0.008). Positive staining for p63 in MCC was infrequent (9 % of primary MCC) and showed no significant association with disease outcome.

CONCLUSIONS

Tumor thickness is significantly associated with disease-free survival in MCC. We recommend that primary tumor thickness be routinely recorded in the pathology reports of patients with primary MCC.

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.

P53 mutation is a rare event in Merkel cell carcinoma of the head and neck

The aim of this retrospective analysis was to evaluate the status of p53 and possible mutations in Merkel cell carcinoma (MCC) cell lines and MCC tissue samples. The p53 mutations are common in different cancer origins but rare in MCCs detected so far. MCCs are highly aggressive neuroendocrine tumors with an enhanced potential to metastasize. Until now, less is known about MCC and new approaches to understand this disease are necessary. RNA and DNA were extracted from two MCC cell lines and 27 archival paraffin-embedded patient samples. After reverse transcription, a real-time PCR and a high-resolution melt analysis were carried out. In both MCC cell lines, we could detect a p53 missense mutation at codon 193 (exon 6) with a change in amino acids (His → Leu). This mutation was equal in both cell lines and was investigated in 27 tissue samples in succession to detect possible accounts for the aggressive behavior of MCCs. Unfortunately, no corresponding p53 mutation could be observed in the investigated tissue samples. A new p53 mutation was detected in MCC cell lines. This mutation could not be determined in patients' samples. Therefore, the aggressiveness of MCC seems to be independent of p53 mutations and other mutations might be responsible for developing MCC.

Molecular pathogenesis of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine skin cancer which is twice as lethal as melanoma as more than one-third of MCC patients will die from this cancer. Although MCC, which primarily affects elderly and immune suppressed individuals, is very rare to date, its incidence is rapidly increasing. In contrast to the immense progress that has been made in the elucidation of the molecular pathogenesis of other cancer entities, until recently there were no clear-cut indications which events drive the carcinogenesis of MCC. Important findings published last year have changed this radically. Hypermethylation of the p14(ARF) promoter and a striking correlation between expression of p63 and the clinical course of MCC have been reported. Most important, however, is the discovery that MCC development in the majority of cases is preceded by the integration of genomic sequences of the hitherto unknown Merkel cell polyomavirus (MCPyV). Now a fundamental improvement in the understanding of MCC pathogenesis as well as the development of new therapeutic approaches based on this knowledge appear to be possible within the near future.

Array-CGH reveals recurrent genomic changes in Merkel cell carcinoma including amplification of L-Myc

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer with poorly characterized genetics. We performed high resolution comparative genomic hybridization on 25 MCC specimens using a high-density oligonucleotide microarray. Tumors frequently carried extra copies of chromosomes 1, 3q, 5p, and 6 and lost chromosomes 3p, 4, 5q, 7, 10, and 13. MCC tumors with less genomic aberration were associated with improved survival (P=0.04). Tumors from 13 of 22 MCC patients had detectable Merkel cell polyomavirus DNA, and these tumors had fewer genomic deletions. Three regions of genomic alteration were of particular interest: a deletion of 5q12-21 occurred in 26% of tumors, a deletion of 13q14-21 was recurrent in 26% of tumors and contains the well-characterized tumor suppressor RB1, and a previously unreported focal amplification at 1p34 was present in 39% of tumors and centers on L-Myc (MYCL1). L-Myc is related to the c-Myc proto-oncogene, has transforming activity, and is amplified in the closely related small cell lung cancer. Normal skin showed no L-Myc expression, whereas 4/4 MCC specimens tested expressed L-Myc RNA in relative proportion to the DNA copy number gain. These findings suggest several genes that may contribute to MCC pathogenesis, most notably L-Myc.

Differential kinetic features by tumour topography in cutaneous small-cell neuroendocrine (Merkel cell) carcinomas

BACKGROUND/OBJECTIVES

Merkel cell carcinomas (MCC) reveal epithelial and neuroendocrine differentiation, but its topographic cell kinetics remains unknown. This study analyses proliferation, apoptosis, and DNA ploidy by topography, features that can help planning therapeutic protocols. This study topographically analyses proliferation, apoptosis, and DNA ploidy.

METHODS

We selected 27 small-cell MCCs (expressing one epithelial and two neural markers, with consistent ultrastructural findings) to evaluate mitotic figure counting, Ki-67 index, apoptosis index based on the in situ end labelling of fragmented DNA (using Escherichia coli DNA polymerase I, Klenow fragment), DNA ploidy, and BCL2 and TP53 immuno-expression. At least 50 high-power fields were screened per topographic compartment (superficial or papillary dermis, and deep or reticular dermis), recording average and standard deviation for each variable. Variables were statistically compared in each tumour compartment using analysis of variance and Student's t-test (significant if P < 0.05).

RESULTS

MCCs revealed superficial aneuploid DNA content, and no topographic differences for proliferation markers. Apoptosis showed significantly lower values in the deep compartment (average, P = 0.0050, and standard deviation, P = 0.0074), correlating with increased BCL2 and TP53 immuno-expressions.

CONCLUSIONS

High homogeneously distributed proliferation and superficial aneuploid DNA content defines MCCs. Apoptosis follows proliferation in superficial compartments, being less variable and proliferation independent in deep compartments, where it is inversely correlated with BCL2/TP53 expression.

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.

TdT expression in Merkel cell carcinoma: potential diagnostic pitfall with blastic hematological malignancies and expanded immunohistochemical analysis

Merkel cell carcinoma is an uncommon aggressive primary cutaneous neuroendocrine carcinoma. Histologically, the differential diagnosis includes the 'small round cell' tumor group, particularly metastatic small cell carcinoma and blastic hematological malignancies involving skin/soft tissues. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase, which is a sensitive and specific antibody for acute lymphoblastic lymphoma with a small proportion of acute myeloid leukemia showing positivity. This study investigates the expression of TdT in 20 cases with initial diagnosis of Merkel cell carcinoma. Archival blocks and slides were retrieved and reviewed and clinical information obtained from patient charts. Immunohistochemistry was performed and graded as: 0, no staining; 1+, less than 50% staining in the cells; 2+, 50% or more staining in the cells. After review, 15 cases were confirmed as Merkel cell carcinoma. Immunohistochemical positivity was as follows: 8/15 cases were positive for TdT with strong nuclear staining, morphologically resembling 'blasts', AE1AE3, CAM5.2 (15/15) (both membrane and paranuclear dot positivity), CD56 and BCL-2 (15/15), Synaptophysin (13/15), Chromogranin A (11/15), NSE (15/15), CK20 (14/15), CK7 (3/15), both CK7 and CK20 (3/15), CD117 (8/15), CD99 (2/15), CD10 (1/15). One case was negative for CK7/CK20. All 15 cases were negative for thyroid transcription factor-1, LCA, CD20, CD3 and CD34. Expanded immunohistochemical panel with positive staining for epithelial/neuroendocrine markers, CK20, negative staining for hematolymphoid markers and awareness of TdT expression and other markers that show overlap with blastic hematological malignancies avoids misinterpretation in the diagnosis of Merkel cell carcinoma. This aids in further diagnosis of Merkel cell carcinoma, avoiding the potential diagnostic pitfall with other small round cell tumors and hematological malignancies primary or metastatic to the skin.

Merkel cell carcinoma: more deaths but still no pathway to blame

Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer with a rising incidence (1500 U.S. cases per year) that now exceeds that of cutaneous T-cell lymphoma and a mortality (33%) exceeding that of melanoma. Despite this impact, little is known about its biology. Recent studies have shown that Ras/MAP kinase activity is absent and possibly detrimental to this cancer. This makes MCC distinct from other UV--induced skin cancers and highlights the question of what drives this malignancy.

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 Cell Carcinomas

Merkel cell carcinoma (MCC) is a rare and extremely aggressive skin cancer that arises from primary neural cells. It presents most commonly in the elderly and immunocompromised patients. Pathologically, MCC should be distinguished from extrapulmonary small cell lung cancer or metastatic small cell lung cancer or a small cell variant of melanoma. The prognosis is based largely on the stage of disease at the time of presentation. Therapeutic options for MCC include wide resection with or without adjuvant radiotherapy or chemotherapy. Novel therapies based on the understanding of the molecular aspects of MCC are currently being explored.

Expression profiles associated with aggressive behavior in Merkel cell carcinoma

Primary neuroendocrine carcinoma of the skin, or Merkel cell carcinoma, is the most aggressive cutaneous neoplasm. In spite of its similarities to small cell carcinomas from other locations, Merkel cell carcinoma shows many peculiarities probably related to its epidermal origin and the etiologic role of UV radiation. We have immunohistochemically investigated 43 markers on a tissue microarray in which 31 surgically resected Merkel cell carcinomas were represented. Of these, 15 patients remained free of disease after removal, whereas 16 developed metastases. Immunoreactivity was scored according to staining intensity and the percentage of positive cells. We found statistically significant correlations between metastatic tumor spread and overexpression of matrix metalloproteinase (MMP) 7, MMP10/2, tissue inhibitor of metalloproteinase 3, vascular endothelial growth factor (VEGF), P38, stromal NF-kappaB, and synaptophysin. Also detected were statistically significant correlations between the expression levels of MMP7 and VEGF, MMP7 and P21, MMP7 and P38, MMP10/2 and VEGF, P38 and synaptophysin, P38 and P53, and P21 and stromal NF-kappaB. These findings may be helpful in predicting the clinical course of Merkel cell carcinoma and are potentially useful for the development of targeted therapies.

Immunohistochemical and ultrastructural investigation on cutaneous neuroendocrine carcinoma: report of a case and review of the literature

We report a tumor in an 80-year-old man that was difficult to distinguish from other tumors, i.e., small cell carcinoma of the lung, PNET/Ewing tumor, malignant lymphoma, or malignant melanoma (amelanotic), and which was finally identified as cutaneous neuroendocrine carcinoma using immunohistochemical and ultrastructural methods. Autopsy did not show any tumors in the lungs, excluding the possibility of small cell carcinoma of the lung. Immunohistochemistry tests gave negative results for LCA, UCHL-1, CD3, and CD20, thereby excluding malignant lymphoma, and the negative results for S-100 protein and HMB-45 ruled out malignant melanoma. The possibility of PNET/Ewing sarcoma was also excluded because of negativity for CD99. In addition, the ultramicrostructure showed intercellular junctional complexes and neuroendocrine granules, indicating that the tumor had characteristics of both epithelial and neuroendocrine tissues. We therefore diagnosed the primary carcinoma of the skin as cutaneous neuroendocrine carcinoma.

The Toker Tumor

Primary neuroendocrine carcinoma of the skin is a relatively rare tumor that was first described by Cyril Toker in 1972. Since the seminal paper by Toker based on simple morphologic observations and detailed clinical correlation, our understanding of the clinical, morphological, and biological attributes of these lesions has grown exponentially with their increased awareness by pathologists and clinicians as well as with the many contributions of modern diagnostic techniques. The present review focuses principally on the various morphologic appearance that these tumors are able to adopt, the role of modern special techniques for diagnosis, and the conditions that need to be considered in their differential diagnosis.

Immunohistochemical study of apoptosis markers and involvement of chemokine CXCR4 in skin Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive cancer of the skin that mainly affects elderly patients. Because of its rarity, there is no established treatment or proven markers to guide therapy or prognosis. Immunohistochemical expression of apoptosis proteins is considered a useful marker of both malignancy and tumour progression. Apoptosis plays a fundamental role in skin homeostasis, and apoptotic cells have been detected in normal and diseased skin. Chemokines possess a wide range of biological activities and CXCR4 is expressed in some cancer cells, where it plays an efficient role in metastasis formation.

OBJECTIVE

To identify immunohistochemical parameters that can help clinicians select the most suitable therapy for skin MCC.

DESIGN

Antibodies against ki67, bcl-2, p53, survivin, p16 and CXCR4 were tested to assess the usefulness of these antigens as indices of proliferation potential and predictors of prognosis.

METHODS

Immunohistochemical detection of apoptosis inhibitors and CXCR4 was performed on tissue from 12 patients with primary MCC. After excision of the primary lesion, five survived and had no metastases, and seven experienced local recurrence or lymph node metastases.

RESULTS

Expression of ki67 and survivin was increased in patients with local recurrence or metastasis (retrospectively classified as 'poor prognosis') compared with those with a 'good prognosis', and bcl-2 expression was significantly greater (P=0.003). P53 and p16 immunostaining was moderate in both groups. A positive correlation was observed between survivin and mutant p53 in the poor prognosis group (r=0.593, P=0.033; regression coefficient). High values of p53 were measured in patients with high levels of survivin and vice versa. CXCR4 was not detected at all.

CONCLUSIONS

Our results show strong MCC cell apoptosis inhibition and a high cell proliferation capacity. The positive correlation between survivin and p53 may be a predictor of MCC spread via the lymphatic network. Absent CXCR4 expression may reflect a less aggressive form, with less efficient development of distant and non-organ-selective metastasis formation.

Eccrine porocarcinoma and Bowen's disease arising in a seborrhoeic keratosis

An association between seborrhoeic keratosis (SK) and malignant tumours is considered to be rare. We observed a case of eccrine porocarcinoma and Bowen's disease (BD) occurring synchronously, forming one lesion in a SK on the abdomen. It is controversial whether malignant neoplasms arising in SK occur only by chance or if pre-existing SK plays a role in pathogenesis. This case suggests an implication of pre-existing SK in the subsequent development of both BD and eccrine porocarcinoma.

Clinicopathological and immunohistochemical analysis of 20 cases of Merkel cell carcinoma in search of prognostic markers

AIMS

To evaluate the clinicopathological and immunohistochemical characteristics of Merkel cell carcinoma (MCC) in an attempt to find new, potentially significant, prognostic markers.

METHODS AND RESULTS

Clinical data and follow-up, histopathological features (pattern, cell size, thickness, mitoses, vascular invasion, lymphocytic infiltration) and immunohistochemical detection [CK20, thyroid transcription factor (TTF-1), chromogranin A, synaptophysin, p53, Ki67, Fli-1, CD99, c-Kit] were evaluated in 20 cases of MCC. Fli-1 and CD99 were detected in 90% and 55% of cases, respectively. Tumour size>30 mm, stage II, 'absent' lymphocytic infiltration, and the presence of>50% of Ki67+ tumour cells, were found to be prognostic indicators of disease-free interval (DFI), but only 'absent' lymphocytic infiltration constituted an independent prognostic factor of DFI after multivariate analysis. For overall survival, the same variables, together with local recurrence and lymph node involvement, had prognostic significance, with only local recurrence as an independent prognostic factor after multivariate analysis.

CONCLUSIONS

Absence of lymphocytic infiltration and Ki67 immunoreactivity in more than 50% of tumour cells should be evaluated in conjunction with other well-known prognostic markers in MCC. Furthermore, recognizing that Fli-1 and CD99 expression is commonly found in MCC by immunohistochemistry may avoid misinterpretation in the differential diagnosis of MCC with other small round cell tumours.

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.

Ets-1 immunohistochemical expression in non-melanoma skin carcinoma

BACKGROUND

Ets-1 oncoprotein is a transcription factor known to regulate the expression of numerous genes important in extracellular matrix remodeling and angiogenesis. Up-regulation of Ets-1 has been shown to be important in a variety of human malignancies and to correlate with prognosis. To our knowledge, this oncoprotein has not been examined in non-melanoma skin carcinomas.

DESIGN

A series of 26 primary cutaneous skin lesions with patient records were independently examined for diagnosis confirmation and immunohistochemical expression by two dermatopathologists. The immunohistochemical expression for Ets-1 (Novocastra, Newcastle Upon Tyne, England, UK) was scored by an average of the mean labeling intensity (MLI), where no nuclear staining = 0, weak nuclear staining = 1, moderate nuclear staining = 2, and strong nuclear staining = 3.

RESULTS

All basal cell carcinoma (BCC) and Merkel cell carcinoma (MCC) cases exhibited negative nuclear staining, for an average MLI of 0. Keratoacanthomas, squamous cell carcinoma in situ (SIS), and well-differentiated squamous cell carcinomas (SCCs) exhibited negative to weak nuclear staining, for an average MLI of 0.4 +/- 0.3. Moderately differentiated SCCs exhibited moderate nuclear staining, for an average MLI of 1.8 +/- 0.6. Poorly differentiated SCCs and metastatic SCCs exhibited very strong nuclear staining, with an average MLI of 2.8 +/- 0.2.

CONCLUSIONS

Ets-1 is not expressed in cutaneous BCC or MCC and is weakly expressed in SIS and forms of well-differentiated SCC. Although the intensity of Ets-1 immunostaining distinguished between well-differentiated and poorly differentiated SCC (p < 0.0001), it failed to discriminate between in situ and well-differentiated SCCs. The preliminary data suggests Ets-1 may be important in the pathogenesis of invasive SCC.

Expression of insulin-like growth factor-I receptor in primary cutaneous carcinomas

BACKGROUND

Insulin-like growth factor-I (IGF-I) is the principal mediator of growth hormone, exerting its effects through binding of the insulin-like growth factor-I receptor (IGF-IR). Post-receptor activation leads to the production of transcription factors involved in cell proliferation, differentiation, transformation, and survival. Data indicate that IGF-IR is involved in tumorigenesis. To our knowledge, this receptor has not been previously studied in primary cutaneous carcinomas.

METHODS

Twenty-five cases of primary cutaneous carcinomas consisting of three keratoacanthoma-type squamous cell carcinomas (KAs), two squamous cell carcinomas in situ (SCCs in situ), eight squamous cell carcinomas (SCCs), three conventional basal cell carcinomas (BCCs), two morpheaform basal cell carcinomas (M-BCCs), and seven Merkel cell carcinomas (MCCs) were analyzed for IGF-IR immunohistochemical expression using IGF-IR mouse monoclonal antibody (dilution 1 : 50) using the avidin-biotin-peroxidase complex method.

RESULTS

Normal epidermis was negative for IGF-IR expression. Normal eccrine glands and outer root sheath strongly expressed IGF-IR. All KAs, SCCs in situ, SCCs, and BCCs were negative for IGF-IR expression. Six of seven (86%) of the MCCs stained with IGF-IR strongly, showing cell membrane accentuation and a perinuclear dot-like pattern.

CONCLUSION

The data suggest that IGF-IR immunopositivity in MCCs might constitute a diagnostic tool in discriminating between SCCs and BCCs. Although the possible pathogenic significance of the perinuclear dot-like staining pattern observed in these neoplasms is unknown, its pattern is similar to what has been previously described with cytokeratin-20 immunostaining.

Merkel cell carcinoma: a clinical, histopathologic, and immunohistochemical review

Merkel cell carcinoma is a rare aggressive neoplasm, with about 400 cases diagnosed in the United States each year. Among the cutaneous-derived neoplasms, it is the most deadliest, with a higher mortality rate than melanoma. Although the classic clinical presentation as a rapidly growing papule in a sun-exposed site of an elderly patient is not specific, certain histopathologic and ancillary pathologic features allow for its discrimination in most cases. Herein, we review the etiology, pathogenesis, clinical, and pathologic attributes as well as the staging treatment and prognosis of this important public health menace.

A study of apoptosis in Merkel cell carcinoma: an immunohistochemical, ultrastructural, DNA ladder, and TUNEL labeling study

We performed immunohistochemical, ultrastructural, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL), and DNA ladder studies of apoptosis in nine cases of Merkel cell carcinoma (MCC). None of the cases showed spontaneous regression as has been reported in several MCCs. Neuron-specific enolase was demonstrated by immunohistochemistry (8/8 MCCs), and staining for cytokeratin 20 was positive (2/8 MCCs). Ultrastructural examination revealed many cytoplasmic dense-cored granules, desmosome-like structures, and intermediate filaments. The granules were seen along the plasma membrane or around perinuclear centrioles. We found various stages of development of apoptotic bodies. Apoptosis resulted in vacuolization and fragmentation of nuclei and phagocytosed bodies in tumor cells. Apoptotic cells were also detected by TUNEL, DNA ladder, and immunostaining using the antibody against Fas (Apo- 1/CD95) antigen. It seems that a high apoptotic rate is a common finding in MCC, although spontaneous regression is an exceedingly rare event. It is thus unlikely that apoptosis alone would explain spontaneous regression.

Spontaneous regression of merkel cell carcinoma: a comparative study of TUNEL index and tumor-infiltrating lymphocytes between spontaneous regression and non-regression group

Some Merkel cell carcinomas (MCC) have been reported to regress spontaneously. To clarify the mechanisms of spontaneous regression (SR) of MCC, we analyzed the TUNEL index, the labeling index of proliferating cell nuclear antigen (PCNA), the labeling index of bcl-2 protein, and the expression of p53 of the tumor cells. We also evaluated the number of infiltrating lymphocytes surrounding the tumor in the tissue specimens. Among seven patients with MCC (SR: n=4; non-regression (NR): n=3), the TUNEL index in the SR group was significantly higher than that in NR group (5.2 and 2.0%, respectively). In addition, the number of lymphocytes around the tumor nests was also significantly increased in the SR group compared to NR group (1576 and 663 cells/mm(2), respectively). Most of the infiltrating lymphocytes were UCHL-1 positive T-cells. There were no significant differences of the PCNA labeling index, the bcl-2 protein labeling index, and the expression p53 between SR and NR group. These results indicate that apoptosis and local T-cell mediated immune response might be involved in spontaneous regression of MCC.

Merkel cell carcinoma: report of 10 cases and review of the literature

BACKGROUND

Merkel cell carcinoma (MCC) is a rare primary neuroendocrine skin tumor that usually arises in the head and neck or the extremities of elderly patients. Because of the limitation of retrospective data, optimal treatment is not well defined.

OBJECTIVE

Our purpose was to present the clinical course and treatment of 10 patients with MCC and review the published literature on MCC.

METHOD

We conducted a retrospective analysis and obtained detailed clinical information for all 10 patients treated for MCC at our institution from 1986 through 1998. The medical literature was also reviewed for natural history and treatment recommendations using MEDLINE search.

RESULTS

Five men and 5 women received their treatment between 1986 and 1998 for MCC (5 had stage IA disease, 4 stage IB, 1 stage II). The mean age was 70.3 years (range, 47-86 years). Seven tumors were located on the head and neck and 3 on extremities. Five of 10 patients had a relapse (mean time before recurrence, 5.7 months) (range, 2 weeks-20 months); one patient had local recurrence, one had regional lymph node recurrence, and 3 had both local and regional lymph node recurrence. In 4 patients systemic metastases developed. Long survival is also noted (6 to > 164 months); 4 patients died of MCC. After initial surgery, 9 patients received radiotherapy at some point and 3 patients also received chemotherapy. Five of 10 patients had 13 previously treated or coexisting malignant neoplasms. In one patient MCC developed in a previously irradiated field. Review of 875 cases showed a male/female ratio of 1.5:1; location of tumors was as follows: head and neck, 47%; extremities, 40%; trunk, 8%; unknown primary site, 5%. Local recurrence was observed in 25%, regional lymph node involvement in 52%, distant metastasis in 34%, and MCC was a cause of death in 34%.

CONCLUSION

MCC has a high incidence of locoregional recurrence with distant metastases that is more common with higher stage lesions. Early local management of smaller lesions results in good long-term survival. It is not known whether prophylactic lymph node dissection and/or radiation and adjuvant radiation increases survival. Long survival can be achieved after treating locoregional recurrence. The role of chemotherapy is still controversial and should be considered in patients with advanced disease and those not thought to be candidates for surgery.

Bcl-2 antisense oligonucleotides (G3139) inhibit Merkel cell carcinoma growth in SCID mice

Merkel cell carcinoma was first described in 1972 by Toker and is an aggressive neuroendocrine skin tumor with a high metastatic potential. Merkel cell carcinoma is thought to derive from the neuroendocrine (Merkel) cells of the skin, although in contrast to fetal and especially adult Merkel cells, Merkel cell carcinomas express high levels of the Bcl-2 oncoprotein. Bcl-2 is capable of blocking programmed cell death and has been shown to play an important role in normal cell turnover, tumor biology, and chemoresistance. High Bcl-2 expression leading to prolonged survival of cells may therefore be of importance in the biological and clinical characteristics of Merkel cell carcinoma. In a SCID mouse xenotransplantation model for human Merkel cell carcinoma, we investigated the influence of the bcl-2 antisense oligonucleotide G3139 (Genta) on tumor growth in comparison with control oligonucleotides or cisplatin. Bcl-2 antisense treatment, targeting the first six codons of the bcl-2 mRNA, resulted in either a dramatic reduction of tumor growth or complete remission, whereas reverse sequence and two-base mismatch control oligonucleotides or cisplatin had no significant antitumor effects compared with saline-treated controls. Apoptosis was enhanced 2.4-fold in the bcl-2 antisense treated tumors compared with the saline-treated group, and no other treatment showed a comparable increase in apoptosis. Our findings suggest that bcl-2 antisense treatment may be a novel approach to improve treatment outcome of human Merkel cell carcinoma.

Unusual presentation of a Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an uncommon, potentially lethal, cutaneous tumor that mainly occurs in sun-exposed skin of the head and neck area of the elderly. We report a case of MCC presenting as a 2-mm crusted erosion on the nose of an elderly patient, the smallest MCC reported thus far in the literature. The optimal management of MCC has not been clearly established. In view of its high local recurrence rate, predilection to metastasis, and significant mortality, aggressive treatment has been advocated. Identification of this tumor at such a small size posed a management dilemma because of lack of prospective treatment data involving biologic markers of prognostic significance for MCC.

Expression of the apoptosis-related oncogenes bcl-2, bax, and p53 in Merkel cell carcinoma: can they predict treatment response and clinical outcome?

Chemotherapy and radiation therapy act predominantly through the induction of apoptosis in malignancies. Merkel cell carcinoma, an aggressive malignancy with prominent apoptosis, has proved to be sensitive to both modes to a certain degree. We used immunohistochemical methods to examine 25 Merkel cell carcinomas and 8 of their lymph node metastases to assess the status of the antiapoptotic gene bcl-2 and 2 proapoptotic genes, wild-type p53 and bax. All tumors showed prominent bax immunopositivity; 76% were positive for bcl-2, and only 28% were positive for p53, the latter presumably reflecting mutated p53. No statistically significant relationship was found between tumor immunopositivity and therapy response or survival. The widespread bax immunopositivity and the apparently low rate of p53 mutations, as suggested by the low rate of p53 immunopositivity, may be related to the presence of prominent apoptosis in Merkel cell carcinoma. The finding of bcl-2 immunopositivity in 76% of the tumors suggests that some of the tumor cells may be resistant to apoptosis-inducing agents.

Merkel cell carcinoma of the external auditory canal invading the intracranial compartment

PURPOSE

To report an unusual case of an intracranial extension of Merkel cell carcinoma originating in the external ear canal and causing neurological deficits.

CASE REPORT

An 86-year-old woman, with a 16-month history of an external auditory canal mass, presented with hemiparesis, facial paralysis, and obtundation. Radiographic images showed an intracranial mass extending into the petrous bone.

METHOD

The patient had a craniotomy for intracranial tumor resection with concurrent mastoidectomy for facial nerve decompression and obtundation and hemiparesis were resolved. Residual tumor was subsequently treated with adjuvant radiation therapy, and facial nerve function consequently improved.

CONCLUSION

Merkel cell tumors rarely invade the intracranial compartments. Residual tumor and neurological deficits may respond to adjuvant radiation therapy.