Merkel细胞癌多瘤病毒阳性的皮肤原发性Merkel细胞癌二例

Merkel cell carcinoma polyomavirus-positive primary cutaneous Merkel cell carcinoma： two case reports

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10cmX8cm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5cm×4cm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MACl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。

Objective To estimate the value of detection of Merkel cell carcinoma polyomavirus （MCPyV） in the diagnosis of Merkel cell carcinoma （MCC）. Methods Two cases of MCC were studied using light microscopy and immunohistochemistry. PCR was performed to detect DNA sequences encoding MCPyV large T antigen（LT）and viral protein I （VP1） in paraffin-embedded tissue specimens from the two patients with MCC, five patients with T cell lymphoma, two normal human controls, as well as in two T cell lymphoma cell lines MAC1 and MAC2. DNA sequencing was also carried out. Results Both of the patients with MCC were male. The patient 1 presented with a mass in the right anterior shin for more than one year, and the patient 2 had a mass in the left knee for more than six months. Skin examination revealed densely distributed pink nodules in the right anterior shin, with confluence into an indurated plaque which measured 10 cm x 8 cm with superficial erosion, exudates and crusts and was surrounded by multiple irregularly sized erythematous nodules with limited mobility in the patient 1, as well as a royal blue, hard, poorly marginated nodular mass measuring 5 cmx d cm in the left medial knee with limited mobility in the patient 2. Pathological manifestations were similar in the two patients. Tumor cells were uniform with large hyperchromatic nuclei, eosinophilic and sparse cytoplasm, and fine chromatin. Mitotic figures were easily seen. Immunohistochemistry revealed that the tumor cells stained positive for pan-cytokeratin, synuclein （Syn）, neuron-specific enolase （NSE）, chromogranin （CgA）, CK20, and Ki-67 （〉 or = 60%）, but negative for S100 protein, HMB45, CD34, thyroid transcription factor 1 （TTF-1）, CK7 and leukocyte common antigen （LCA）. MCPyV DNA was detected in both MCC specimens, but absent in the other skin specimens or T cell lymphoma cell lines. Conclusions MCC has distinctive clinical and pathological appearance. Immunohistochemistry and detection of MCPyV DNA sequences using PCR may be beneficial to the definitive diagnosis of MCC.