Merkel cell polyomavirus DNA detection in lesional and nonlesional skin from patients with Merkel cell carcinoma or other skin diseases

Summary Background A novel polyomavirus, the Merkel cell polyomavirus (MCPyV), has recently been identified in Merkel cell carcinoma (MCC). Objectives To investigate the specificity of this association through the detection, quantification and analysis of MCPyV DNA in lesional and nonlesional skin biopsies from patients with MCC or with other cutaneous diseases, as well as in normal skin from clinically healthy individuals. Methods DNA was extracted from lesional and nonlesional skin samples of patients with MCC or with other cutaneous diseases and from normal‐appearing skin of clinically healthy subjects. MCPyV DNA was detected by polymerase chain reaction (PCR) and quantified by real‐time PCR. Additionally, the T antigen coding region was sequenced in eight samples from seven patients. Results MCPyV DNA was detected in 14 of 18 (78%) patients with MCC, five of 18 (28%) patients with other skin diseases (P = 0·007) and one of six (17%) clinically healthy subjects. In patients with MCC, viral DNA was detected in nine of 11 (82%) tumours and in 10 of 14 (71%) nontumoral skin samples (P = 0·66). MCPyV DNA levels were higher in MCC tumours than in nontumoral skin from patients with MCC, and than in lesional or nonlesional skin from patients with other cutaneous disorders. Signature mutations in the T antigen gene were not identified in the two MCC tumour specimens analysed. Conclusions High prevalence and higher levels of MCPyV DNA in MCC supports a role for MCPyV in tumorigenesis. However, the high prevalence of MCPyV in the nontumoral skin and in subjects without MCC suggests that MCPyV is a ubiquitous virus.     

Merkel cell carcinoma with heterologous rhabdomyoblastic differentiation: the role of immunohistochemistry for Merkel cell polyomavirus large T-antigen in confirmation

Merkel cell carcinoma (MCC) represents an uncommon and lethal form of cutaneous malignancy. Historically, the pathogenesis of MCC has been presumed to be linked to ultraviolet light overexposure, but recently, it has been documented that some examples harbor polyomavirus genome, the presence of which is presumed to be of pathogenetic importance. Extremely rare cases of MCC may show heterologous differentiation. We report an example of MCC with heterologous rhabdomyosarcomatous differentiation, the third such case to date, with emphasis on its distinction from fusion-negative alveolar rhabdomyosarcoma. The role of immunohistochemistry for Merkel cell polyomavirus large T-antigen in this differential diagnosis is emphasized.     

Merkel cell carcinoma showing regression after biopsy: Evaluation of programmed cell death 1‐positive cells

We present a cases of Merkel cell carcinoma (MCC) with Merkel cell polyomavirus that showed complete regression after biopsy. The exact mechanism of regression in MCC has remained unclear. It has been reported that apoptosis caused by T‐cell immunity was implicated in the regression, and programmed cell death 1 (PD‐1), an inhibitory receptor, was expressed in approximately half of tumor‐infiltrating T cells in MCC. However, the contribution of PD‐1‐positive cells for the regression of MCC has not been evaluated. We examined the rate of PD‐1‐positive cells among the peritumoral mononuclear cells, which showed that the percentage of PD‐1‐positive cells in the case was significantly lower compared with in MCC without regression. We propose that PD‐1‐positive cells suppress tumor immunity for MCC, and that reduction of PD‐1‐positive cells may be associated with tumor regression.     

Merkel细胞癌多瘤病毒阳性的皮肤原发性Merkel细胞癌二例

【摘要】 目的 报道Merkel细胞癌多瘤病毒阳性的Merkel细胞癌2例。 方法 对诊治的2例Merkel细胞癌进行光镜观察及免疫组化标记,聚合酶链反应（PCR）检测Merkel细胞癌多瘤病毒并测序。 结果 2例均为男性,例1右下肢胫前肿物1年余,皮肤科检查见右胫前密集粉红色结节,融合成10 cm × 8 cm肿块,质硬,部分表面糜烂伴渗出及结痂,肿块周围亦可见多个大小不一的红色结节,活动性差。例2左膝肿物6月余,皮肤科检查见左膝内侧5 cm × 4 cm紫蓝色结节型肿物,质硬,边界不清,活动性差。2例患者皮损组织病理表现相似,肿瘤细胞大小一致,细胞核大、深染,染色质细腻,核分裂象易见;胞质少,红染。免疫组化：广谱细胞角蛋白（pan-CK）、细胞角蛋白20（CK20）、突触素（Syn）、嗜铬素（CgA）和神经元特异性烯醇化酶（NSE）均阳性,Ki-67（≥60%）阳性;细胞角蛋白7（CK7）、S100蛋白、HMB45、CD34、甲状腺转录因子1（TTF-1）和白细胞共同抗原（LCA）表达均阴性。2例Merkel细胞癌均经PCR检测到Merkel细胞癌多瘤病毒,而5例皮肤T细胞淋巴瘤、2例正常人皮肤和2例T细胞淋巴瘤细胞系MAC1和MAC2A均未检测到Merkel细胞癌多瘤病毒。 结论 Merkel细胞癌具有特征性的临床和组织病理表现,免疫组化标记、PCR检测Merkel细胞癌多瘤病毒对明确诊断具有重要作用。 【关键词】 癌,Merkel细胞; 多瘤病毒属     

Patched 1 expression in Merkel cell carcinoma

The relevance of Hedgehog signaling in Merkel cell carcinoma has only been addressed by a few studies with conflicting results. Thus, we aimed to establish the expression of Hedgehog signaling molecules in Merkel cell carcinoma to characterize causes of aberrant expression and to correlate these findings with the clinical course of the patients. Immunohistochemistry was performed for Sonic, Indian, Patched 1 (PTCH1) and Smoothened on patients’ tumor tissue. Respective mRNA expression was analyzed in 10 Merkel cell carcinoma cell lines using quantitative real‐time polymerase chain reaction. PTCH1 sequencing and DNA methylation microarray analyses were carried out on tumor tissues as well as cell lines. PTCH1 immunoreactivity in Merkel cell carcinoma was similar to that of basal cell carcinomas, which both significantly differed from PTCH1 immunoreactivity in healthy skin. Most PTCH1 mutations found were synonymous or without known functional impact. However, on average, the promoter regions of both PTCH1 were hypomethylated independently from PTCH1 gene expression or Merkel cell polyomavirus status. PTCH1 and GLI1/2/3 genes were differently expressed in different cell lines; notably, there was a significant correlation between GLI2 and PTCH1 mRNA expression. Similar to PTCH1 protein expression in patient tissues, PTCH1 gene expression in Merkel cell carcinoma cell lines is highly variable, but due to the similar methylation pattern across Merkel cell carcinoma cell lines, effects other than methylation seem to be the reason for the differential expression and PTCH1 appears to be upregulated by GLI as a classical Hedgehog target gene.     

Merkel cell carcinoma – a retrospective analysis of 17 cases

OBJECTIVE: To report clinical experience with the rare neuroendocrine Merkel cell carcinoma of the skin. SUBJECTS AND SETTING: Seventeen patients with Merkel cell carcinoma of the skin treated at the Departments of Dermatology and ENT, Krankenhaus Dresden-Friedrichstadt, Dresden, Germany, during the years 1984-2000 were evaluated. METHODS: A retrospective analysis was performed. Age and sex distribution, clinical data and therapy were collected. Outcome measures including overall survival, tumour-free survival and relapse-free survival were determined. RESULTS: Six male and 11 female patients with an age range of 68-90 years (mean age 73.3 years) were identified. The primary tumour localization was head and neck region (n = 8), upper limbs (8), lower limbs (1). Twelve patients presented in tumour stage I, three in stage II and one in stage III. First line therapy was complete surgical excision with wide margins in 16 patients followed by loco-regional radiation in 12 of 16 cases. In 16 patients follow up data were available. After primary treatment complete response was achieved in 14 of 16 patients (87.5%), two patients had a partial response. The median of relapse-free survival was 44 weeks [mean +/- standard deviation: (44 +/- 118) weeks]. The median of overall survival was 102 weeks [mean +/- standard deviation: (137 +/- 94) weeks]. Three patients with a PR after primary treatment had a median overall survival of only 48 weeks [mean +/- standard deviation: (51 +/- 20) weeks]. CONCLUSIONS: Primary surgical treatment with wide excision combined with radiotherapy seems to be a reasonable first-line treatment but prospective controlled multicentre trials are necessary for validation.     

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

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

Combined intraepidermal neuroendocrine (Merkel cell) and squamous cell carcinoma in situ with CM2B4 negativity and p53 overexpression(*)

Primary cutaneous neuroendocrine carcinoma, also known as Merkel cell carcinoma (MCC), usually presents as a dermal and/or subcutaneous tumor. Rarely, it is confined to the epidermis or adnexal epithelium [MCC in situ (MCCIS)]. Little is known about the spectrum of features and biology of MCCIS. Herein, we report a case of MCCIS arising on the cheek of a 77-year-old Caucasian male, which was associated with squamous cell carcinoma in situ. The tumor cells of both the neuroendocrine and squamous components prominently involved adnexal structures but did not invade the dermis. The tumor cells with neuroendocrine features were immunoreactive for cytokeratin-20, chromogranin and synaptophysin. They also expressed p53 but were non-reactive with the monoclonal antibody CM2B4. Lack of labeling for CM2B4 is in keeping with prior observations of combined squamous and MCC. Our findings support the concept of a distinct subtype of virus-independent cutaneous neuroendocrine carcinoma that differs from conventional MCC. The observed overexpression of p53 suggests that the development of this tumor type may be related to chronic ultraviolet damage.     

Merkel细胞癌3例临床与病理分析

目的探讨Merkel细胞癌的临床与病理特点、病因学、诊断及鉴别诊断。方法观察3例Merkel细胞癌的组织病理特点和免疫组化染色结果,并复习相关文献。结果 3例均为老年患者,女2例,男1例。镜下见肿瘤主要位于真皮,呈巢索状和弥漫片状分布,癌细胞圆形、卵圆形或梭形,大小及形态较一致,胞质较少,核染色质细颗粒状,病理性核分裂像多见。免疫组化见CK20和神经内分泌标记阳性,HMB45,TTF-1,LCA和CD99等阴性。结论 Merkel细胞癌是一种发生于皮肤的少见的高度恶性神经内分泌肿瘤,易局部复发或转移。近年来发现的Merkel细胞多瘤病毒可能是其重要的致病因子。其临床病理及特征性的免疫组化表达有助于诊断及鉴别诊断。目前的治疗方法主要有手术切除和辅助放疗及化疗。     

Merkel cell carcinoma in situ: New insights into the cells of origin

We report a case of a 71-year-old male who presented with a small skin-coloured plaque on his cheek. Histopathology demonstrated an intraepidermal carcinoma with follicular involvement. No evidence of dermal invasion was seen. Immunohistochemical studies showed areas of positive staining for CK20, EMA and synaptophysin. Histopathology findings were found to be most consistent with a diagnosis of intraepidermal carcinoma with features of Merkel cell carcinoma in situ, in combination with a squamous cell carcinoma in situ, with follicular involvement. Recent advances and findings suggest Merkel cell polyomavirus MCPyV-positive Merkel cell carcinoma and MCPyV-negative Merkel cell carcinoma have different cells of origin from different germ layers.     

Histogenesis of pure and combined Merkel cell carcinomas: An immunohistochemical study of 14 cases

The histogenesis of Merkel cell carcinoma (MCC) has remained unresolved. Moreover, one of the questions is whether pure MCC and combined MCC represent the same histogenesis and entity. The existence of combined MCC suggests that MCC likely arise from pluripotent stem cells. Merkel cells (MC) localize within the bulge area, which is populated by hair follicle stem cells. We used hair follicle stem cell markers to investigate whether MCC share certain characteristics of these stem cells. Fourteen MCC specimens were examined histologically and immunohistochemically. There were six pure MCC and eight combined MCC. In six combined MCC, both MCC components and squamous components at least focally shared the expression of one or more of cytokeratin (CK)15, CK19 and CD200, which are hair follicle stem cell markers. On the other hand, four cases of pure MCC showed partially distinct CK19 expression, but did not show CK15 and/or CD200 expression. There was a distinct difference between pure MCC and combined MCC on the expression of hair follicle stem cell markers. The normal skin expressed CK15, CK19 and CD200 in the bulge area, whereas CK15 and CD200 were absent in the MC‐rich glabrous skin and touch domes. The results led us to hypothesize that combined MCC originate from the hair follicle stem cells. We postulate that combined MCC undergo multidirectional differentiation into squamous, glandular, mesenchymal and Merkel cells. Further investigation is warranted to confirm the histogenesis of pure MCC and combined MCC.