Llombart B, Monteagudo C, López-Guerrero J A, Carda C, Jorda E, Sanmartín O, Almenar S, Molina I, Martín J M, Llombart-Bosch A
Department of Pathology, Instituto Valenciano de Oncología, Valencia, Spain.
Histopathology. 2005 Jun;46(6):622-34. doi: 10.1111/j.1365-2559.2005.02158.x.
To evaluate the clinicopathological and immunohistochemical characteristics of Merkel cell carcinoma (MCC) in an attempt to find new, potentially significant, prognostic markers.
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.
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.
评估默克尔细胞癌（MCC）的临床病理及免疫组化特征，以寻找新的、可能具有重要意义的预后标志物。
对20例MCC患者的临床资料及随访情况、组织病理学特征（形态、细胞大小、厚度、有丝分裂、血管侵犯、淋巴细胞浸润）以及免疫组化检测结果[细胞角蛋白20（CK20）、甲状腺转录因子（TTF-1）、嗜铬粒蛋白A、突触素、p53、Ki67、Fli-1、CD99、c-Kit]进行了评估。分别在90%和55%的病例中检测到Fli-1和CD99。肿瘤大小>30 mm、Ⅱ期、“无”淋巴细胞浸润以及Ki6 +肿瘤细胞>50%被发现是无病生存期（DFI）的预后指标，但多因素分析后只有“无”淋巴细胞浸润是DFI的独立预后因素。对于总生存期，相同变量以及局部复发和淋巴结受累具有预后意义，多因素分析后只有局部复发是独立预后因素。
在MCC中，应结合其他已知的预后标志物评估肿瘤细胞中淋巴细胞浸润的缺失情况以及超过50%的Ki67免疫反应性。此外，认识到免疫组化中MCC常见Fli-1和CD99表达可能避免在MCC与其他小圆细胞肿瘤的鉴别诊断中出现错误解读。
