Merkel cell carcinoma with squamous and sarcomatous differentiation

Merkel cell carcinoma is an aggressive neuroendocrine tumor historically thought to arise from neural crest-derived cutaneous neuroendocrine cells. Recent evidence supports an epidermal origin. We present a case of Merkel cell carcinoma arising on the upper arm of a 94-year-old woman that had multiple morphologic patterns: small cells typical of Merkel cell carcinoma, malignant cells with squamous differentiation and malignant poorly differentiated spindle cells. Subsequent metastatic disease in regional lymph nodes showed only the small cells and the malignant spindle cells. To our knowledge, this is the first case of Merkel cell carcinoma showing these three patterns of differentiation at first presentation. This morphology raises the possibility that Merkel cell carcinomas may arise from epidermal stem cells that can differentiate along different lines.     

Merkel cell carcinoma

Merkel cell carcinoma is an unusual primary cutaneous tumor with an aggressive biologic nature. Following surgical treatment, 40% of patients have local recurrences develop, 55% have regional lymph node metastases develop, and 49% have distant metastases develop. We have treated four patients with Merkel cell carcinoma; only one of the four patients was alive and well after 2 years. Two patients died of metastatic disease, one at 11 months following initial treatment and one at 39 months. The fourth patient had a rapid recurrence following initial treatment and is currently in remission following chemotherapy for regional metastases. Recent reports indicate that chemotherapy may be helpful in treating patients with recurrent or metastatic Merkel cell carcinoma.     

Merkel cell carcinoma

Merkel cell carcinoma (cutaneous neuroendocrine carcinoma) is an uncommon, highly malignant, neuroendocrine skin tumour. Typically, the primary is a fast-growing tough dermal nodule that is characterized histologically by uniform round cells with a small cytoplasmic rim. The tumour cells express the cytokeratins 8, 18, 19, 20, neurofilament, synaptophysin, chromogranin, and neuron-specific enolase. A high frequency of local recurrences (25-77%) and lymph-node metastases (50%) are characteristic features of Merkel cell carcinoma. The 5-year survival rate is 30-74%. Merkel cell carcinomas are highly radiosensitive. Thus, besides surgical methods, radiation should be included into the treatment concept in every stage. We present four cases of Merkel cell carcinoma with different courses for a review-like discussion of this disease giving instructions for rapid diagnosis and effective therapy.     

Merkel cell carcinoma

ABSTRACT: Merkel cell carcinoma is a rare cutaneous malignancy that occurs mainly in the ultraviolet‐exposed areas of the head and neck region and has a mortality rate higher than that of melanoma (33%) with a tendency to recur. The clinical features, diagnosis, work up, and current recommendations for treatment of Merkel cell carcinoma are discussed.     

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     

皮肤Merkel细胞癌伴鳞状细胞癌一例

患者男,76岁,因左耳前肿物2个月,破溃1个月就诊.2个月前左耳前面颊部无明显诱因出现一约黄豆大小的丘疹,迅速长大,1个月前表面出现破溃,无自觉症状.2周前左耳后出现一蚕豆大小肿大的淋巴结,有触痛,抗炎治疗后缩小.     

Merkel cell polyomavirus status is not associated with clinical course of Merkel cell carcinoma

The majority of Merkel cell carcinomas (MCCs) are associated with the recently identified Merkel cell polyomavirus (MCV). However, as it is still unclear to which extent the presence of MCV impacts tumor characteristics or clinical outcome, we correlated the MCV status of tumor lesions obtained from 174 MCC patients including 38 MCC patients from Australia and 138 MCC patients from Germany with clinical characteristics, histomorphology, immunohistochemistry, and course of the disease. MCV DNA was present in 86% of MCCs and, in contrast to previous reports, no significant difference in MCV prevalence was present between Australian and German MCC cases. When patients were stratified according to their MCV status, only tumor localization (P=0.001), gender (P=0.024), and co-morbidity, i.e., frequency of patients with previous skin tumors (P=0.024), were significantly different factors. In contrast, year of birth and diagnosis, age at diagnosis, or histological type and features representing the oncogenic phenotype such as mitotic rate or expression of p16, p53, RB1, and Ki67 were not significantly different between MCV-positive and MCV-negative MCCs. MCV status also did not influence recurrence-free, overall, and MCC-specific survival significantly. In summary, although MCV-positive and MCV-negative MCCs may have different etiologies, these tumors have comparable clinical behaviors and prognosis.     

Insights into the Merkel cell phenotype from Merkel cell carcinoma cell lines

Merkel cell carcinoma (MCC) of the skin is an aggressive form of skin cancer and is being seen with increasing incidence in Queensland. We have recently established a number of MCC cell lines and characterized these for growth, morphology, expression of neuroendocrine markers and radiation sensitivity. As a result, cell lines were grouped into four classes by their morphology in a similar way to small cell lung cancer (SCLC) cell lines. Types I and II cell lines grew slowly as tight spherical clusters suspended in the medium, with Type II cell lines less densely packed than the Type I cell lines. Type III cell lines grew as flat 2-dimensional clusters and had shorter doubling times and Type IV cell lines grew as adherent monolayers and had the shortest doubling times. Expression of neuroendocrine markers distinguished those with a classic phenotype from those with a variant one. Mainly morphological Types I and II retained the classic phenotype while Classes III and IV had a variant phenotype. The range of surviving fraction at 2 Gray (SF2 0.2-0.45) seen in MCC cell lines was not as high as seen in SCLC cell lines but the variant ones tended to be more radiation resistant. Examination of POU proteins showed that neuroendocrine phenotype was linked with expression of brn-2, and growth in suspension with brn-3c.     

Presence of the Merkel cell polyomavirus in Merkel cell carcinoma combined with squamous cell carcinoma in a patient with chronic arsenism

We present a case of Merkel cell carcinoma (MCC) coincident with squamous cell carcinoma (SCC) on the breast of a woman with chronic arsenism. This case demonstrates the distinct association of chronic arsenism with two different primary cutaneous carcinomas. Merkel cell polyomavirus (MCPyV) was identified in the lesional skin of the MCC but not in that of the SCC, suggesting there are different interactions of MCPyV in the pathogenesis of SCC and MCC related to arsenic. Physicians need to be vigilant in the occurrence of both SCC and MCC in patients with chronic arsenism. To our knowledge, this is the first study to show the presence of MCPyV in the MCC but not the SCC portion of an arsenic‐induced tumour.     

Merkel cell carcinoma in situ

BACKGROUND: Merkel cell carcinoma (MCC) is a dermal small blue-cell tumor that occurs in the elderly on the sun damaged head and neck. Epidermal involvement is unusual and MCC limited to the epidermis is very rare. CASE REPORT: A slightly tender pink hyperkeratotic papule was noted on the dorsal right hand of a 76-year-old man with a history of multiple skin cancers. An intraepidermal proliferation of small blue cells distributed in nests and single units at all levels of the epidermis was found within a solar keratosis and adjacent to an area of squamous cell carcinoma in situ. Cytokeratin 20 and neuron specific enolase highlighted these cells and failed to reveal dermal involvement. There was no residue on re-excision. CONCLUSION: We report the third case of MCC in situ. These lesions have only been reported in association with squamous neoplasms on the extremities.