结直肠锯齿状病变104例形态学及细胞增殖活性的观察

Clinicopathologic features and proliferative status of colorectal serrated lesions： a study of 104 cases

目的探讨结直肠锯齿状病变增生性息肉（HP）、广基锯齿状腺瘤（SSA）、传统锯齿状腺瘤（TSA）的临床特征，组织病理学诊断，鉴别诊断及细胞增殖状况。方法复习北京军区总医院2002年11月至2007年12月2628例病理诊断为结直肠息肉／腺瘤的病理切片，从中收集104例结直肠锯齿状病变，综合文献标准进行分类，观察各类型病变临床病理学特征，以及细胞增殖指数Ki-67的表达特点。结果104例锯齿状病变中包括HP60例，TSA20例，SSA11例，混合性锯齿状息肉／腺瘤7例，混合性锯齿状息肉／腺瘤＋普通腺瘤6例。对各型组织学特征进行总结归纳。免疫组织化学显示正常结肠黏膜Ki-67阳性细胞位于基底（隐窝下1／3），呈间隔分布；51例HP中阴性或阳性细胞数量〈25％的40例（78％），大多数阳性位于隐窝下1／3（基底）；15例TSA中11例阳性细胞数量在25％～50％或〉50％，其中大多数位于隐窝中1／3，少数（2例）隐窝弥漫分布；SSA的数量与分布和TSA相似；相比之下低级别管状腺瘤26例中24例（92％）阳性数量〉50％，18例（69％）分布于隐窝表面，6例（23％）弥漫分布；高分化管状腺癌10例全部呈弥漫分布，7例Ki-67阳性指数在70％左右。阳性细胞多少与分布部位差异有统计学意义，阳性细胞X^2=34．601，P=0．000，阳性分布X^2=63．077，P=0．000。结论HP、SSA、TSA组织学鉴别诊断的主要难点是在HP与SSA两者之间，SSA锯齿状隐窝基底扩张结构特征是诊断的关键，比细胞学改变更重要。TSA与SSA的主要形态鉴别在于TSA锯齿状腺体有明显异型增生（普通腺瘤样增生）以及几乎所有TSA异型增生的腺体都不与黏膜肌相邻（ECF现象）。细胞增殖指数Ki-67数量及分布的表达可为HP、SSA及TSA鉴别诊断提供一定帮助。锯齿状腺瘤中TSA和SSA的Ki-67表达指数都比普通腺瘤要低。

Objective To study the clinicopathologic features and proliferative status of colorectal hyperplastic polyp （HP）, sessile serrated adenoma （SSA） and traditional serrated adenoma （TSA）. Methods One hundred and four cases colorectal serrated lesions were collected from 2628 cases of eolorectal polyps during the period from November, 2002 to December, 2007. The elinicopathologic features and expression of proliferation marker Ki-67 were studied. Results On the basis of morphologic examination, 60 cases were classified as HP, 20 cases as TSA, 11 cases as SSA, 7 cases as mixed HP/ SSA/TSA, and 6 cases as mixed serrated polyp/adenoma and tubular adenoma, lmmunohistochemical study for Ki-67 showed that 40 cases （78%） of the 51 cases of HP were either mostly negative or rarely （ 〈25% cells） positive. Most of the positive cells were located at crypt bases. Among the 15 cases of TSA, 11 of them revealed positive cryptal cells （25% to 50% or 〉 50% positivity）. Most of the positive cells were located in mid portion of crypts. The number and distribution of Ki-67 positive cells in SSA were similar to those in TSA but were significantly different from those in tubular adenoma and adenocarcinoma （X^2 = 34.601, P=0.000;X^2 =63.077,P=0.000, respectively）. Conclusions HP, SSA and TSA have their morphologic characteristics, with some overlapping features noted. The distinction between SSA and HP can be difficult. Diagnosis of SSA relies mostly on architectural rather than cytologic features. The distinction between TSA and SSA depends mainly on the presence of dysplasia. Ectopic crypt formation is almost exclusively seen in TSA. The distribution and percentage of Ki-67-positive cells are also helpful in subtyping of various colorectal serrated lesions. In general, the proliferative index is lower in serrated adenoma （TSA or SSA） than in tubular adenoma.