Combined Merkel cell carcinoma (MCC) and squamous cell carcinoma (SCC) have classically been regarded as more aggressive than conventional, pure, Merkel cell polyomavirus (MCPyV)-positive MCC. It is still unknown whether combined MCC and SCC are more aggressive than pure, MCPyV-negative MCC, and the origin of both the SCC and MCC elements of these combined tumors has not been elucidated. The main objective of this systematic review was to assess whether combined MCC and SCC tumors are associated with a worse prognosis than pure MCC; the secondary goals were the characterization of the clinical and histopathological features of these combined neoplasms. A total of 38 studies, including 152 patients, were selected for review. In total, 76% of the cases were MCPyV-negative, whereas 4% were MCPyV-positive. The most frequent histopathological pattern was that of an SCC in situ combined with a dermal MCC (36%), followed by both an in situ and invasive SCC combined with a dermal MCC (20%). Forty-seven percent of all cases fitted in the morphology of the so-called “collision tumors”. Three combined MCC cases that would fit in the morphological category of collision tumors presented both squamous and neuroendocrine elements in their respective nodal metastases. The mean overall survival was 36 months, comparable to that of pure, MCPyV-negative MCC. This review found similarly aggressive behavior for combined MCC and SCC and pure, MCPyV-negative MCC. Preliminary data strongly suggest that all MCPyV-negative MCC tumors, whether combined or pure, are part of a common spectrum.
传统上认为，默克尔细胞癌（MCC）与鳞状细胞癌（SCC）的复合型肿瘤比传统的、纯粹的、默克尔细胞多瘤病毒（MCPyV）阳性的MCC更具侵袭性。然而，复合型MCC与SCC是否比纯粹的MCPyV阴性MCC更具侵袭性仍不明确，且这类复合型肿瘤中SCC与MCC成分的起源尚未阐明。本系统性综述的主要目的是评估复合型MCC与SCC肿瘤是否比纯粹MCC预后更差；次要目标是对这些复合型肿瘤的临床与组织病理学特征进行描述。共纳入38项研究，涵盖152例患者进行分析。总体而言，76%的病例为MCPyV阴性，而4%为MCPyV阳性。最常见的组织病理学模式为原位SCC合并真皮MCC（36%），其次为原位及浸润性SCC合并真皮MCC（20%）。所有病例中47%符合所谓“碰撞瘤”的形态学特征。三例符合碰撞瘤形态学分类的复合型MCC病例在其各自淋巴结转移灶中同时存在鳞状与神经内分泌成分。平均总生存期为36个月，与纯粹的MCPyV阴性MCC相当。本综述发现复合型MCC与SCC和纯粹的MCPyV阴性MCC具有相似的侵袭性行为。初步数据强烈提示，所有MCPyV阴性MCC肿瘤（无论复合型或纯粹型）均属于同一疾病谱系。
Combined Merkel Cell Carcinoma and Squamous Cell Carcinoma: A Systematic Review
肿瘤(癌症)患者之家