膀胱小细胞癌的研究进展

Advances in small cell carcinoma of bladder

膀胱小细胞癌（small cell carcinoma,SCC）是一种少见的恶性肿瘤,占原发性膀胱癌的0.48%-1%。SCC在组织发生、病理特征、治疗和预后等方面与常见的移行细胞癌有很大差别。一般认为,膀胱SCC起源于膀胱内具有多种分化潜能的的干细胞。病理上,SCC由弥漫性分布的小圆形细胞组成,细胞胞质稀少,胞核深染,核仁不明显,缺乏间质反应;电镜下,胞质内细胞器稀少,出现致密核心的神经内分泌颗粒是其特征;SCC表达上皮性标志如EMA、角蛋白和CEA,以及神经内分泌标志如NSE和CM-A等。临床上,SCC多见于男性,男女发病率之比为4.8∶1,平均发病年龄〉60岁;无痛性肉眼或镜下血尿为常见的临床表现,多数患者就诊时已为中晚期病例。SCC应与分化较差的移行细胞癌、恶性淋巴瘤、恶性黑色素瘤以及类癌等细胞体积较小的肿瘤鉴别,确诊依靠病理和免疫组织化学检查。由于SCC是一种全身性疾病,易于早期发生转移,治疗上,应根据肿瘤分期和细胞类型,考虑以顺铂为基础的全身化疗,辅以手术或放射治疗,以延长患者生存时间。膀胱SCC预后较差,平均生存时间为19.6个月,5年生存率仅为8%。

Small cell carcinoma （SCC） of bladder, account for 0.48%--1% of primary bladder cancer, is a rare entity. As compared to transitional cell carcinoma, the most common malignancy of bladder, SCC has its own characteristics in histogenesis, pathologic feature, therapeutic strategy and prognosis. It is generally accepted that SCC of bladder originated from stem cells with multi-differentiated potency. Pathologically, SCC is composed of uniform small cells with scanty cytoplasm and hyperchromatic round to oval nuclei with dispersed chromatin and absent or inconspicuous nucleoli. Interstitial reaction is minimal or absent. Few organelles and dense-core neuroendocrine granules are the most prominent findings of SCC in electron microscopic examination. SCC expresses epithelial markers such as EMA, cytokeratin, CEA and neuroendocrine markers such as NSE, CM-A, etc. Clinically, SCC is more often diagnosed in man, with a male to female ratio of 4.8：1. The average onset age is more than 60- year. Painless gross or microscopic hematuria is the most frequent presenting symptom. The majority of patients are diagnosed as middle or end stage of disease. SCC should be differentiated from poor differentiated TCC, malignant lymphoma and melanoma, carcinoid of bladder and other tumors which contain relative small cells. The diagnosis of SCC should be confirmed with pathologic feature and immunohistochemical staining. As SCC of bladder may be a systemic disease with tendency of metastasis in early stage, therapeutically, platinum-based systemic chemotherapy, in combination with operation or radiation should be considered as the most rational strategy. As the average survival time is only 19.6 months and 5-year survival rate is less than 8%, the prognosis of SCC is poor.