结直肠广基锯齿状腺瘤的临床病理与免疫组织化学特性

目的 探讨结直肠广基锯齿状腺瘤(SSA)的临床病理形态学特征及Ki67、p53、癌胚抗原(CEA)、尾型同源盒转录因子2(CDX2)、角蛋白7(CK7)的免疫组化表达.方法 收集结直肠SSA11例,增生性息肉(HP)51例,混合性HP/SSA 1例,总结其隐窝结构、细胞特点以及与其他锯齿状病变的鉴别诊断要点.对SSA、混合性HP/SSA和HP进行Ki67、p53、CEA、CDX2、CK7的免疫组化染色,并以25例绒毛管状腺瘤(VTA)和管状腺瘤(TA)作为对照.结果 SSA的组织学特点主要为隐窝结构异常,锯齿状腺体扩张,基底部膨大,呈倒T或L型,并与黏膜肌相邻.隐窝中上部细胞可有一定非典型性,出现椭圆型核及核仁.免疫组化染色结果显示,p53的阳性表达率在HP(11.8%)、SSA(20.0%)、VTA(41.2%)和TA(75.0%)中逐渐增高,差异有统计学意义(χ2=17.996,P=0.000).CDX2和CK7在HP和SSA中的表达差异无统计学意义.在10例SSA中,Ki67阳性指数为26%～50%者5例,阳性指数>50%者3例;阳性部位位于隐窝基底+侧面6例.Ki67在SSA中的表达与HP、VTA和TA相比,差异有统计学意义(Ki67阳性数量χ2=34.601,P=0.000;阳性部位χ2=63.077,P=0.000).结论 SSA的形态学主要表现为隐窝结构和细胞的变化,隐窝结构改变较细胞学改变更为重要;Ki67和p53在SSA中的表达特点有助于与其他锯齿状病变的鉴别诊断.

Clinicopathological and innnunohistochemical features of colorectal sessile serrated adenoma

Objective To investigate the elinicopathological characteristics and expression status of Ki67, p53, CEA, CDX, CK7 in colorectal sessile serrated adenoma (SSA). Methods The clinicopathological data of 11 cases of SSA, 51 cases of hyperplastic polyp (HP) and one case with mixed HP/SSA were reviewed and analyzed retrospectively. The expression of Ki67, p53, CEA, CDX and CK7 were detected by immunohistochemistry. Results The major histological features in SSA were architectural abnormality in crypts, dilatation of serrated crypt bases like an inverted "T" or "L" shape adjacent to muscularis mucosa. Atypical cells containing round to oval nuclei and nucleoli were also observed. The immunohistochemical staining showed that the expression of p53 increased gradually from HP to TA: 11.8% in HP, 20.0% in SSA, 41.2% in VTA and 75.0% in TA, with a significant difference among the groups (χ2=17. 996, P=0. 000). However, no significant difference in the expression of CDX and CK7 was observed between HP and SSA. Of the 10 SSA cases, positive expression of Ki67 was found in cells located in the base or middle part of crypt in 6 cases, positive cells index was 26%-50% in 5 cases, and >50% in 3. Compared with the expression of Ki67 in the HP, VTA and VA, SSA showed a significant difference in both the positive cell number and in the positive regions. (positive number: χ2=34. 601, P=0.000; positive regions:χ2=63.077, P=0.000). Conclusion Morphological diagnosis of SSA was mainly based on crypt architectural and cellular abnormalities, and the crypt architectural abnormality may be more important than cellular features. Detection of 1053 and Ki67 expression may be helpful in differential diagnosis and understanding the nature of SSA.